The degradation of starch in barley grains is a primary step of beer production. The addition of an appropriate amount of gibberellin (GA) promotes the production of fermentable sugars, beneficial to the brewing industry. However, the response of proteomics in germinating barley to GA and abscisic acid (ABA) treatments is not thoroughly understood. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) proteomics analysis was performed to illustrate the change of proteins in Tibetan wild barley XZ72 and XZ95 under GA and ABA treatments during germination. XZ72 had more proteins upregulated than XZ95 under GA treatment, while under ABA treatments, XZ95 had more proteins upregulated than XZ72. Concerning the proteins involved in energy metabolism under GA treatment, XZ72 had more proteins upregulated than XZ95. Among the 174 proteins related to starch metabolism, 31 proteins related to starch hydrolysis, such as α-amylase, α-glucosidase, and β-fructofuranosidase, showed higher relative abundance in control and GA treatments in XZ72 than in XZ95. Analysis of correlation between proteins and metabolites indicated that higher hydrolase activity is beneficial for the accumulation of fermentable sugars during germination. On the other hand, 26 starch-synthesis-related proteins were upregulated in XZ95 under ABA treatment. It may be suggested that GA-induced proteins act as accelerators of starch degradation, while ABA-induced proteins inhibit starch degradation. The current results showed that XZ72 is highly capable of allocating the starch-hydrolyzing enzymes, which play important roles in starch breakdown.Keywords: abscisic acid (ABA); barley; germination; gibberellin (GA); proteomics;

Water deficient or drought stress is a major factor causing deterioration or instability of malt barley quality. In the studies on the influence of drought stress during grain filling on malt quality formation or metabolic changes, it is quite difficult to obtain the uniform plant individuals and water condition in pot or field experiments. In this study, we combined barley spike in vitro culture and PEG-6000 simulated drought to determine the genotypic difference in the changes of grain metabolites and the expression level of the genes encoding β-amylase and β-glucan using two Tibetan wild barley accessions and two cultivated genotypes differing in malt quality stability under drought stress. Under simulated drought, grain weight and β-glucan content were dramatically reduced and β-amylase activity was increased, and a lot of metabolites were markedly changed for all genotypes. On the whole, the changes were relatively smaller in the wild barley. Meanwhile, the expressions of Bmy1 related to β-amylase synthesis and GSL1, GSL4 and GSL7 related to β-glucan synthesis were up-regulated and down-regulated under drought stress, respectively, being consistent with the changes of β-amylase activity and β-glucan content in the four barley genotypes. The current results showed that PEG-6000 simulated drought and spike in intro culture may provide the basically similar information on grain development or metabolites as do in the field experiments, and it is suitable for use in studies on the influence of drought stress on quality traits during grain filling stage of barley or other cereal crops.

The toxicity of many heavy metals in plants is closely associated with its subcellular distribution and chemical forms. The subcellular distribution and chemical forms of cobalt (Co2+) were investigated using 3 barley genotypes differing in Co2+ toxicity resistance, namely Yan66 (resistant), Ea 52 (sensitive), and Humai 4 (moderate), under two Co2+ levels (25 and 100 µM). Higher Co2+ level in cultural solution significantly increased Co2+ accumulation in all subcellular fractions, with vacuole and cell wall having higher concentration. In comparison with 25 µM Co2+, 100 µM Co2+ treatment caused significant increase of Co2+ concentration in the forms of F-NaCl (extracted with 1 M NaCl), F-Ac (extracted with 2% HAc), F-HCl (extracted by 0.6 M HCl), and F-residue (residue forms) in both shoots and roots. There was a significant difference among genotypes in Co2+ subcellular distribution and chemical forms, with Ea52 accumulating more Co2+ in organelles and Yan66 accumulating more Co2+ in vacuole and cell wall. Moreover, the inorganic form of Co2+ extracted with 80% ethanol (F-ethanol) and water-soluble form (F-H2O) were significantly increased in Ea52, while Yan66 accumulated more Co2+ in the forms of low-bioavailable molecules (F-NaCl, F-HAc, and F-HCl). The results suggest that the vacuolar sequestration and cell wall deposition of Co2+ is a key resistant mechanism for genotype Yan66.

•The role of Ca in alleviating Co stress was investigated using two barley genotypes differing in Co toxicity tolerance.•The effect of Co toxicity on growth, photosynthetic parameters, oxidative stress differed between the two barley genotypes.•Addition of Ca in growth medium alleviated Co toxicity by reducing Co uptake and enhancing antioxidant capacity.•The effect of Ca in alleviating Co toxicity differed between the two barley genotypes.Cobalt (Co) contamination in soils is becoming a severe issue in environment safety and crop production. Calcium (Ca), as a macro-nutrient element, shows the antagonism with many divalent heavy metals and the capacity of alleviating oxidative stress in plants. In this study, the protective role of Ca in alleviating Co stress was hydroponically investigated using two barley genotypes differing in Co toxicity tolerance. Barley seedlings exposed to 100 µM Co showed the significant reduction in growth and photosynthetic rate, and the dramatic increase in the contents of reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH) and oxidized glutathione (GSSG), and the activities of anti-oxidative enzymes, with Ea52 (Co-sensitive) being much more affected than Yan66 (Co-tolerant). Addition of Ca in growth medium alleviated Co toxicity by reducing Co uptake and enhancing the antioxidant capacity. The effect of Ca in alleviating Co toxicity was much greater in Yan66 than in Ea52. The results indicate that the alleviation of Co toxicity in barley plants by Ca is attributed to the reduced Co uptake and enhanced antioxidant capacity.

•The change of metabolite during germination is time- and genotype dependent.•Sugars and amino acids are the most dramatically changed compounds.•Addition of GA enhanced the activities of starch-degrading enzymes.•Effect of GA and ABA on metabolite differs between barley genotypes.Sugar degradation during grain germination is important for malt quality. In malting industry, gibberellin (GA) is frequently used for improvement of malting quality. In this study, the changes of metabolite profiles and starch-degrading enzymes during grain germination, and as affected by GA and abscisic acid (ABA) were investigated using two wild barley accessions XZ72 and XZ95. Totally fifty-two metabolites with known structures were detected and the change of metabolite during germination was time- and genotype dependent. Sugars and amino acids were the most dramatically changed compounds. Addition of GA enhanced the activities of starch-degrading enzymes, and increased most metabolites, especially sugars and amino acids, whereas ABA had the opposite effect. The effect varied with the barley accessions. The current study is the first attempt in investigating the effect of hormones on metabolite profiles in germinating barley grain, being helpful for identifying the factors affecting barley germination or malt quality.

Phenolic acids have been of considerable interest in human nutrition because of their strong antioxidative properties. However, even in a widely grown crop, such as barley, their genetic architecture is still unclear. In this study, genetic control of two main phenolic acids, ferulic acid (FA) and p-coumaric acid (p-CA), and their associations with agronomic traits were investigated among 134 Tibetan wild barley accessions. A genome-wide association study (GWAS) identified three DArT markers (bpb-2723, bpb-7199, and bpb-7273) associated with p-CA content and one marker (bpb-3653) associated with FA content in 2 consecutive years. The contents of the two phenolic acids were positively correlated with some agronomic traits, such as the first internode length, plant height, and some grain color parameters, and negatively correlated with the thousand-grain weight (TGW). This study provides DNA markers for barley breeding programs to improve the contents of phenolic acids.

Low phosphorus (LP) causes a dramatic change of root system architecture in plants, which is possibly mediated by signaling pathways of hormones. In order to understand the regulatory mechanisms of the root development under LP, we examined the potential role of phytohormones in response to LP using three barley genotypes, differing in LP tolerance, namely 2 Tibetan wild barley genotypes XZ99 (LP tolerant) and XZ100 (LP sensitive), and a cultivated barley ZD9 (LP moderately tolerant). The results showed that LP stress caused a number of changes in root development, with XZ99 having less primary root growth inhibition, more lateral root and root hair formation than the other two genotypes. Meanwhile, LP stress also resulted in the dramatic changes in plant hormone contents, with changed extent and pattern differing among the three genotypes. The relative expression of genes responsible for indole acetic acid (IAA) and ethylene synthesis in roots also showed a significant difference among genotypes in both control and LP conditions. It can be concluded that the root system of Tibetan wild barley XZ99 adapts to phosphorus deficiency by changing the signal transduction pathway mediated by auxin, ethylene and cytokinins. However, further studies are needed to elucidate the behaviors of the key genes involved in the hormone-related response.

Aluminum (Al) and manganese (Mn) toxicity commonly coexists in acid soil, so the crop cultivars suitable for planting in acid soil should show high tolerance to both elements simultaneously. However, it is still not clear if the toxicity of Mn and Al on plant growth is antagonistic or synergistic, and the plants with Al tolerance are also tolerant to Mn toxicity. In this study, three barley genotypes (one Tibetan wild and two cultivated), differing in Al tolerance, were characterized for growth and physiological responses to Al or Mn toxicity as well as the combined treatment of the two toxic elements. Interestingly, it has been found that the combined treatment of both metals was less affected in comparison with Al or Mn treatment alone, in terms of plant growth, Al or Mn concentration in plant tissues, and photosynthetic parameters, indicating antagonistic interaction of Al and Mn for their effect on plant growth and physiological traits. The results also showed that there was a dramatic difference among barley genotypes in Mn toxicity tolerance and XZ16 showed much higher tolerance than other two genotypes. High Mn tolerance is mainly described to less Mn uptake and lower Mn concentration in plants, and Mn tolerance is independent of Al tolerance.

Purple grains in barley are caused by the presence of anthocyanin in both aleurone and pericarp, and the trait is controlled by one or two dominant genes. In this study, we demonstrated that purple grain was controlled by a single dominant gene using reciprocal crosses between Yuyaohongdamai and AC Parkhill or ACCA. The close linkage between grain color and spike type (controlled by Vrs1) was found in the crosses between Yuyaohongdamai and ACCA. The purple-grain gene was mapped on chromosome 2HL between the SSR markers Bmag0125 (1.2 cM) and GBMS244 (2.8 cM), and was about 5.1 cM distal from Vrs1. The marker enrichment in the target region was carried out by amplifying barley EST- and rice homologous gene-based searching for polymorphic loci adjacent to Pre2. Four of the newly developed markers were mapped in the Pre2 gene region. The purple lemma and pericarp gene (Pre2) was then finely mapped between InDel marker PQJ1056 (from EST BM096525) and HvOs04g47170 with genetic distance of 0.3 and 0.1 cM, respectively.

•Ionomics and TMT-labeling based proteomics were used to study low-K tolerance.•288 differentially accumulated proteins in K deficient leaves were identified.•Tibetan wild barley XZ153 has a higher capability of developing low K tolerance.•A hypothetical model of a low-K tolerance mechanism was presented.In previous studies, we found Tibetan wild barley accessions with high tolerance to low K. In this study, ionomics and proteomics analyses were done on two wild genotypes (XZ153, tolerant and XZ141, sensitive), and a cultivar (B1031, tolerance to low K) to understand the mechanism of low-K tolerance. XZ153 was much less affected by low K stress than the other two genotypes in plant biomass and shoot K content. A total of 288 differentially accumulated proteins were identified between low-K and normal K treated plants. Among them, 129 proteins related to low-K tolerance were mainly involved in defense, transcription, signal transduction, energy, and protein synthesis. The analysis of tandem mass tag (TMT) detected 51 proteins which were increased in relative abundance under low K in XZ153, but unaltered or decreased in XZ141. The proteomics results showed that XZ153 is highly capable of rearranging ion homeostasis and developing an antioxidant defense system under low-K stress. Moreover, ethylene response and phenylpropanoid pathways could determine the genotypic difference in low-K tolerance. The current results confirmed the possibility of Tibetan wild barley providing low-K tolerant germplasm and identified some candidate proteins for use in developing the cultivars with low-K tolerance.

Soil salinity is one of the m ajor abiotic stresses affecting crop growth and yield worldwide. Barley is a species with higher salt tolerance among cereal plants and rich in genetic variation. It is quite important to understand the physiological mechanisms of genotypic difference in salt tolerance. In this study, physiological and biochemical responses of a Tibetan wild barley genotype XZ16 (salt tolerant) and a cultivated cultivar Yerong (salt sensitive) to salt stress were investigated. The results showed that the two genotypes differed dramatically in their responses to salt stress (150 and 300 mM NaCl) in terms of plant biomass, Na+ accumulation and Na+/K+ ratio in roots and shoots, chlorophyll content, xylem sap osmolarity and electrolyte leakage. XZ16 showed less biomass reduction, lower Na+/K+ ratio and electrolyte leakage, higher xylem sap osmolarity, and vacuolar H+-ATPase and H+-PPase activities than Yerong under 300 mM NaCl. The higher salt tolerance of XZ16 may be attributed to its lower concentration of Na+ influx or more sequestration into the vacuoles. The results indicate that the Tibetan wild barley is useful for improvement of cultivated barley in salt stress tolerance.

Haze formation in beer is a trait closely related to beer quality and it is largely affected by the haze active proteins (HAPs) in barley (Hordeum vulgare L.). Up to date, little is known about the genetics of HAPs and relevant genes. In this study, we obtained the beer samples from a Franklin/Yerong double haploid (DH) population and the two parents using micro-malting and micro-brewing, and determined tannin-related HAPs. It was found that there was a wide difference in HAPs among all lines of the DH population, and Yerong had a higher HAPs content than Franklin. Quantitative trait locus (QTL) analysis identified five QTLs associated with HAPs in beer, being located on chromosomes 1HS, 5HL and 6HS, respectively. The loci QHAP1.FrYe-1H and QHAP2.FrYe-1H were overlapped in the short arm of chromosome 1H, and they controlled HAP1 and HAP2, respectively. Moreover, the candidate genes were also predicted based on published whole barley genome sequence and corresponding gene annotations.

•Difference exists in amino acid sequence of BTI-CMe between SE+ve and SE−ve types.•BTI-CMe of SE−ve haplotype has lower haze formation in beer than SE+ve haplotypes.•Higher content of BTI-CMe and/or tannic acid in beer results in higher turbidity.•There is a significant interaction between BTI-CMe and tannic acid.•Haze activity of BTI-CMe was significantly correlated with tannic acid concentration.Our previous study found that the critical protein in SE (silica eluted) proteins is BTI-CMe, and assumed that SE−ve malt for brewing may improve the haze stability in beer. In this study, we investigated the difference in gene sequence and corresponding amino acid sequence of BTI-CMe between SE+ve and SE−ve types. The results showed that there were 7 amino acid differences between Yerong (SE−ve) and Franklin (SE+ve). Two types BTI-CMe were expressed in vitro and purified successfully. By adding the purified BTI-CMe into commercial beer, we found that both original turbidity and alcohol chill haze degree of beer were increased. BTI-CMe of SE−ve haplotype showed a lower level of haze formation in beer than SE+ve haplotype. Response surface methodology (RSM) was conducted to determine the relationship between BTI-CMe and tannic acid, and their effects on haze formation. It was found that (1) higher content of BTI-CMe and/or tannic acid in beer would give rise to higher turbidity; (2) there was a significant interaction between BTI-CMe and tannic acid; (3) haze activity disparity of BTI-CMe between two types was significantly and positively correlated with the tannic acid concentration.

•The pre-treatments of NIRS data improved the regression models.•Lin_LSSVR and RBF_LSSVR model outperform PLS and RBF_NN model for barley GPC.•NIR spectra showed good performance in the determination of GPC.•Thirteen spectral wavelengths showed high contribution to calibration models.Grain protein content (GPC) is an important quality determinant in barley. This research aimed to explore the relationship between GPC and diffuse reflectance spectra in barley. The results indicate that normalizing, and taking first-order derivatives can improve the class models by enhancing signal-to-noise ratio, reducing baseline and background shifts. The most accurate and stable models were obtained with derivative spectra for GPC. Three multivariate calibrations including least squares support vector machine regression (LSSVR), partial least squares (PLS), and radial basis function (RBF) neural network were adopted for development of GPC determination models. The Lin_LSSVR and RBF_LSSVR models showed higher accuracy than PLS and RBF_NN models. Thirteen spectral wavelengths were found to possess large spectrum variation and show high contribution to calibration models. From the present study, the calibration models of GPC in barley were successfully developed and could be applied to quality control in malting, feed processing, and breeding selection.

β-Amylase activity (BAA) and thermostability (BAT) are important traits for malt quality. In this study, 138 Tibetan annual wild barley accessions and 20 cultivated genotypes differing in BAA were planted and analyzed in 2009 and 2012. Significant differences were detected among genotypes in BAA and BAT. The cultivated genotypes had a mean BAA of 1137.6 U/g and a range of from 602.1 to 1407.5 U/g, while the wild accessions had a mean of 1517.9 U/g and a range of from 829.7 to 2310.0 U/g. The cultivated genotypes had a mean relative residual β-amylase activity (RRBAA) of 61.6% and a range of from 22.2% to 82.3%, while the wild barleys had a mean of 57.8% and a range of from 21.9% to 96.1%. Moreover, there was a significant difference among genotypes in the response of RRBAA to the temperature and duration of heat treatment. The wild barleys had wider variation in BAA and BAT than cultivated genotypes.β-淀粉酶活性(BAA)与热稳定性(BAT)是啤用大麦品质的重要性状, 本研究旨在明确青藏高原一年生野生大麦BAA 和BAT 的基因型差异, 鉴定可用于啤用大麦品质育种的特异种质材料。青藏高原一年生野生大麦中具有高BAA 和BAT 的基因型, 可为啤用大麦品质育种提供特异遗传材料; 解析了不同温度与高温处理不同时间对BAT 的影响及其机理。本研究以138 个青藏高原一年生野生大麦基因型和20 个栽培大麦品种为材料, 在杭州大田条件下种植两年(2008∼2009 年和 2011∼2012 年), 利用 Megazyme 公司研制的试剂盒 BETAMYL-3® kit 法测定BAA, 用两点法测定BAT。BAA 和BAT 在供试的基因型之间均有显著的差异, 且野生大麦的基因型变异明显大于栽培品种, 青藏高原一年生野生大麦中具有高BAA 和BAT 值的野生大麦材料。

Rice plants employ two strategies to cope with Cr toxicity: immobilizing Cr ions into cell walls to reduce its translocation and activating antioxidant defense to mitigate Cr-induced oxidative stress.The investigation aimed at understanding the physiological and proteomic responses of rice seedlings to hexavalent chromium (Cr6+) stress was conducted using two rice genotypes, which differ in Cr tolerance and accumulation. Cr toxicity (200 µM) heavily increased the accumulation of H2O2 and \({\text{O}}_{2}^{{ \cdot-}}\), enhanced lipid peroxidation, decreased cell viability and consequently inhibited rice plant growth. Proteomic analyses suggest that the response of rice proteome to Cr stress is genotype- and Cr dosage-dependent and tissue specific. Sixty-four proteins, which show more than fourfold difference under either two Cr levels, have been successfully identified. They are involved in a range of cellular processes, including cell wall synthesis, energy production, primary metabolism, electron transport and detoxification. Two proteins related to cell wall structure, NAD-dependent epimerase/dehydratase and reversibly glycosylated polypeptide were greatly up-regulated by Cr stress. Their enhancements coupled with callose accumulation by Cr suggest that cell wall is an important barrier for rice plants to resist Cr stress. Some enzymes involved in antioxidant defense, such as ferredoxin-NADP reductase, NADP-isocitrate dehydrogenase, glyoxalase I (Gly I) and glutamine synthetase 1 (GS1) have also been identified in response to Cr stress. However, they were only detected in Cr-tolerant genotype, indicating the genotypic difference in the capacity of activating the defense system to fight against Cr-induced oxidative stress. Overall, two strategies in coping with Cr stress in rice plants can be hypothesized: (i) immobilizing Cr ions into cell walls to reduce its translocation and (ii) activating antioxidant defense to mitigate Cr-induced oxidative stress.

A hydroponic experiment was conducted to elucidate the difference in growth and cell ultrastructure between Tibetan wild and cultivated barley genotypes under moderate (150 mM NaCl) and high (300 mM NaCl) salt stress. The growth of three barley genotypes was reduced significantly under salt stress, but the wild barley XZ16 (tolerant) was less affected relative to cultivated barley Yerong (moderate tolerant) and Gairdner (sensitive). Meanwhile, XZ16 had lower Na+ and higher K+ concentrations in leaves than other two genotypes. In terms of photosynthetic and chlorophyll fluorescence parameters, salt stress reduced maximal photochemical efficiency (Fv/Fm), net photosynthetic rate (Pn), stomatal conductance (Gs), and intracellular CO2 concentration (Ci). XZ16 showed relatively smaller reduction in comparison with the two cultivated barley genotypes. The observation of transmission electron microscopy found that fundamental cell ultrastructure changes happened in both leaves and roots of all barley genotypes under salt NaCl stress, with chloroplasts being most changed. Moreover, obvious difference could be detected among the three genotypes in the damage of cell ultrastructure under salt stress, with XZ16 and Gairdner being least and most affected, respectively. It may be concluded that high salt tolerance in XZ16 is attributed to less Na+ accumulation and K+ reduction in leaves, more slight damage in cell ultrastructure, which in turn caused less influence on chloroplast function and photosynthesis.

Plants adopt several strategies to maintain cellular ion homeostasis, including physiological, biochemical, cellular, subcellular, and molecular mechanisms for fighting against salt stress. We investigated the responses of tolerant Tibetan wild barley (XZ16), tolerant (CM72) and sensitive (Gairdner) barley cultivars at physiological, cellular, and molecular levels. The results revealed that salinity induced a significantly greater reduction in total root length, surface area, diameter, and total volume in Gairdner than in CM72 and XZ16. Analysis of gene expression using quantitative RT-PCR showed that transcripts of vacuolar H+-ATPase and inorganic pyrophosphatase (HvHVA/68 and HvHVP1) were more abundant in leaves and roots of XZ16 and CM72 than those of Gairdner. Observation of electron microscopy detected the difference in the damage of leaf and root ultrastructure among the three genotypes under salt stress, with XZ16 and Gairdner being least and most affected, respectively. Subcellular study showed that a primary strategy to protect the cytosol against sodium toxicity was compartmentalization of sodium ions into soluble fraction (vacuoles). Gairdner showed drastically stronger sodium-specific fluorescence visualized by CoroNa-Green, a sodium-specific fluorophore, than CM72 and XZ16.

The domestication of cultivated barley has been used as a model system for studying the origins and early spread of agrarian culture. Our previous results indicated that the Tibetan Plateau and its vicinity is one of the centers of domestication of cultivated barley. Here we reveal multiple origins of domesticated barley using transcriptome profiling of cultivated and wild-barley genotypes. Approximately 48-Gb of clean transcript sequences in 12 Hordeum spontaneum and 9 Hordeum vulgare accessions were generated. We reported 12,530 de novo assembled transcripts in all of the 21 samples. Population structure analysis showed that Tibetan hulless barley (qingke) might have existed in the early stage of domestication. Based on the large number of unique genomic regions showing the similarity between cultivated and wild-barley groups, we propose that the genomic origin of modern cultivated barley is derived from wild-barley genotypes in the Fertile Crescent (mainly in chromosomes 1H, 2H, and 3H) and Tibet (mainly in chromosomes 4H, 5H, 6H, and 7H). This study indicates that the domestication of barley may have occurred over time in geographically distinct regions.

The effect of nitrogen forms on photosynthesis and anti-oxidative systems of barley plants under chromium stress was studied in a hydroponic experiment. The treatments comprised three chromium concentrations (0, 75, and 100 μM) and three N forms (NH4)2SO4, urea, and Ca(NO3)2. In comparison with the urea or (NH4)2SO4 fed plants, the Ca(NO3)2 fed plants had higher net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, transpiration rate, photosynthetically active radiation utilization efficiency, variable to maximum chlorophyll fluorescence ratio, and the content of chlorophylls and carotenoids. Cr toxicity caused oxidative stress in all plants but the Ca(NO3)2 fed plants had the least oxidative stress. Moreover, the Ca(NO3)2 fed plants had higher activities of anti-oxidative enzymes and content of non-enzymatic antioxidants than the urea or (NH4)2SO4 fed plants. In addition, the Ca(NO3)2 fed plants had higher N and lower Cr content in all plant tissues than the urea or (NH4)2SO4 fed plants. The current results indicate that the reasonable choice of N fertilizer is important for barley production on the Cr-contaminated soils.

A hydroponic experiment was conducted to determine the possible effect of exogenous glutathione (GSH) in alleviating chromium (Cr) stress through examining plant growth, chlorophyll contents, antioxidant enzyme activity, and lipid peroxidation in rice seedlings exposed to Cr toxicity. The results showed that plant growth and chlorophyll content were dramatically reduced when rice plants were exposed to 100 μM Cr. Addition of GSH in the culture solution obviously alleviated the reduction of plant growth and chlorophyll content. The activities of some antioxidant enzymes, including superoxide dismutase, catalase (CAT) and glutathione reductase in leaves, and CAT and glutathione peroxidase in roots showed obvious increase under Cr stress. Addition of GSH reduced malondialdehyde accumulation and increased the activities of these antioxidant enzymes in both leaves and roots, suggesting that GSH may enhance antioxidant capacity in Cr-stressed plants. Furthermore, exogenous GSH caused significant decrease of Cr uptake and root-to-shoot transport in the Cr-stressed rice plants. It can be assumed that GSH is involved in Cr compartmentalization in root cells.

The Near East Fertile Crescent is well recognized as a primary center of barley origin, diversity, and domestication. A large number of wild barleys have been collected from the Tibetan Plateau, which is characterized by an extreme environment. We used genome-wide diversity array technology markers to analyze the genotypic division between wild barley from the Near East and Tibet. Our results confirmed the existence of Tibetan wild barley and suggested that the split between the wild barleys in the Near East and those in Tibet occurred around 2.76 million years ago (Mya). To test the concept of polyphyletic domestication of barley, we characterized a set of worldwide cultivated barley. Some Chinese hulless and six-rowed barleys showed a close relationship with Tibetan wild barley but showed no common ancestor with other cultivated barley. Our data support the concept of polyphyletic domestication of cultivated barley and indicate that the Tibetan Plateau and its vicinity is one of the centers of domestication of cultivated barley. The current results may be highly significant in exploring the elite germplasm for barley breeding, especially against cold and drought stresses.

The formation of haze is a serious quality problem in beer production. It has been shown that the use of silica elute (SE)–ve malt (absence of molecular weight (MW) ∼14000 Da) for brewing can improve haze stability in the resultant beer, and the protein was identified as a barley trypsin inhibitor of the chloroform/methanol type (BTI-CMe). The objectives of this study were to determine (1) the allelic diversity of the gene controlling BTI-CMe in cultivated and Tibetan wild barley and (2) allele-specific (AS) markers for screening SE protein type. A survey of 172 Tibetan annual wild barley accessions and 71 cultivated barley genotypes was conducted, and 104 wild accessions and 35 cultivated genotypes were identified as SE+ve and 68 wild accessions and 36 cultivated genotypes as SE–ve. The allelic diversity of the gene controlling BTI-CMe was investigated by cloning, alignment, and association analysis. It was found that there were significant differences between the SE+ve and SE–ve types in single-nucleotide polymorphisms at 234 (SNP234), SNP313, and SNP385. Furthermore, two sets of AS markers were developed to screen SE protein type based on SNP313. AS-PCR had results very similar to those obtained by immunoblot method. Mapping analysis showed that the gene controlling the MW∼14 kDa band was located on the short arm of chromosome 3H, at the position of marker BPB-0527 (33.302 cM) in the Franklin/Yerong DH population.

Tibetan wild barley is rich in genetic diversity with potential allelic variation useful for salinity-tolerant improvement of the crop. The objectives of this study were to evaluate salinity tolerance and analysis of the allelic function of HvHKT1 and HvHKT2 in Tibetan wild barley. Salinity tolerance of 189 Tibetan wild barley accessions was evaluated in terms of reduced dry biomass under salinity stress. In addition, Na+ and K+ concentrations of 48 representative accessions differing in salinity tolerance were determined. Furthermore, the allelic and functional diversity of HvHKT1 and HvHKT2 was determined by association analysis as well as gene expression assay. There was a wide variation among wild barley genotypes in salt tolerance, with some accessions being higher in tolerance than cultivated barley CM 72, and salinity tolerance was significantly associated with K+/Na+ ratio. Association analysis revealed that HvHKT1 and HvHKT2 mainly control Na+ and K+ transporting under salinity stress, respectively, which was validated by further analysis of gene expression. The present results indicated that Tibetan wild barley offers elite alleles of HvHKT1 and HvHKT2 conferring salinity tolerance.

The effect of aluminum and chromium on two barley genotypes differing in Al tolerance was studied in a hydroponic experiment. Al stress decreased plant growth, biomass production, chlorophyll content and photosynthetic efficiency determined as variable to maximum chlorophyll fluorescence ratio (Fv/Fm), net photosynthetic rate (PN), intercellular CO2 concentration (ci), stomatal conductance (gs) and transpiration rate (E) less in an Al-tolerant genotype Gebeina than in an Al-sensitive genotype Shang 70–119. Cr stress also caused marked reduction in growth and photosynthetic traits in barley plants. Higher reduction was observed at pH 4.0 as compared to pH 6.5. Combined stress of Cr and Al, caused further reduction in growth and photosynthetic parameters.

Chromium contamination in soil has become a severe threat to crop production and food safety. The experiment was conducted using a rice DH population to detect the QTLs associated with Cr tolerance. Seventeen putative QTLs associated with growth traits included three additive loci and fourteen epistatic loci. These loci were distributed on 11 rice chromosomes, and their contribution to the phenotypic variation ranged from 2.44 to 10.08%. Two QTLs located at the similar genetic region on chromosome ten were associated with shoot Cr concentration and translocation from roots to shoots, respectively; and they accounted for 11.65 and 11.22% of the phenotypic variation. In addition, six QTLs related to Zn concentration and translocation was found on chromosomes 1, 2, 4, 5, 7 and 12. Meanwhile epistatic effect existed in the two additive QTLs of qRZC1 and qRZC7. Most of QTLs controlling Zn concentration had small genotypic variance and qSRZ4 related to Zn translocation showed growth condition-dependent expression.

An efficient induction system and regeneration protocol based on mature barley embryos were developed. Embryos isolated from mature seeds, dehusked by hand and inoculated with longitudinally bisected sections, showed low contamination and high primary callus-forming capability. The influences of nine culture media on primary callus induction and germination from the mature embryos of barley cultivars Golden Promise and Zaoshu 3 were analyzed. The results showed that the two cultivars had much higher values of primary callus induction in the B16M6D medium as compared to the other eight medium formulations, with a frequency of 74.3% and 78.4% for Golden Promise and Zaoshu 3, respectively. Furthermore, Zaoshu 3 demonstrated particularly high stability in callus induction over the different media, indicating its potential utilization in callus induction and regeneration for its good agronomic traits and wide adaption. There were significant differences amongst 11 barley genotypes in terms of primary callus induction in the optimum medium, with percentages of callus induction and germination response ranging from 17.9% to 78.4% and 2.8% to 47.4%, respectively. Green plantlets of Dong 17, Golden Promise, and Zaoshu 3 were successfully developed from primary calli through embryogenesis, with green plant differentiation frequencies ranging from 9.7% to 21.0% across genotypes.

The Qinghai-Tibetan Plateau in China is considered to be one of the original centers of cultivated barley. At present, little is known about the phytase activity (Phy) or phytic acid content (PA) in grains of Tibetan annual wild barley. Phy and PA were determined in grains of 135 wild and 72 cultivated barleys. Phy ranged from 171.3 to 1299.2 U kg−1 and from 219.9 to 998.2 U kg−1 for wild and cultivated barleys, respectively. PA and protein contents were much higher in wild barley than in cultivated barley. Tibetan annual wild barley showed a larger genetic diversity in phytase activity and phytic acid and protein contents and is of value for barley breeding. There is no significant correlation between phytase activity and phytic acid or protein content in barley grains, indicating that endogenous phytase activity had little effect on the accumulation of phytic acid.

Waterlogging is a major abiotic stress limiting barley (Hordeum vulgare L.) yield and its stability in areas with excessive rainfall. Identification of genomic regions influencing the response of yield and its components to waterlogging stress will enhance our understanding of the genetics of waterlogging tolerance and the development of more tolerant barley cultivars. Quantitative trait loci (QTLs) for grain yield and its components were identified using 156 doubled haploid (DH) lines derived from a cross between the cultivars Yerong (waterlogging-tolerant) and Franklin (waterlogging-sensitive) grown under different conditions (waterlogged and well drained). A total of 31 QTLs were identified for the measured characters from two experiments with two growth environments. The phenotypic variation explained by individual QTLs ranged from 4.74% to 55.34%. Several major QTLs determining kernel weight (KW), grains per spike (GS), spikes per plant (SP), spike length (SL) and grain yield (GY) were detected on the same region of chromosome 2H, indicating close linkage or pleiotropy of the gene(s) controlling these traits. Some different QTLs were identified under waterlogging conditions, and thus different markers may have to be used in selecting cultivars suitable for high rainfall areas.

Identification of Cr-tolerant lines in a rice DH population was conducted based on the modified weighted function analysis. The significant difference was found between the two parents and among DH population lines, with lines 117, 101 and parent ZYQ8 showing the high Cr tolerance, lines 41 and 49 showing Cr sensitivity. A dramatic difference also existed in Cr accumulation of plant tissues, with lines 19, 18 and 1, 5 having the minimum and maximum shoot Cr accumulation, respectively, and line 19, parent JX17 and lines 1, 56, ZYQ8 having the minimum and maximum root Cr accumulation, respectively. There was a significant difference in shoot/root ratio of Cr accumulation among the population, with line 18 and parent ZYQ8 ranking the tops and lines 109, 71, 19, parent JX17 ranking the bottoms. Zn uptake and accumulation was reduced when the plants were exposed to Cr stress. In addition, three QTLs were detected, which are, respectively, associated with Cr accumulation in shoot and root, and ratio of shoot to root.

Salinity is a major abiotic stress to barley (Hordum vulgare L.) growth and yield. In the current study, quantitative trait loci (QTL) for yield and physiological components at the late growth stage under salt stress and non-stress environments were determined in barley using a double haploid population derived from a cross between CM72 (salt-tolerant) and Gairdner (salt-sensitive). A total of 30 QTLs for 10 traits, including tiller numbers (TN), plant height, spikes per line (SPL), spikes per plant (SPP), dry weight per plant, grains per plant, grain yield, shoot Na+ (NA) and K+ concentraitions (K) in shoot, and Na+/K+ ratio (NAK), were detected, with 17 and 13 QTLs under non-stress and salt stress, respectively. The phenotypic variation explained by individual QTL ranged from 3.25 to 29.81%. QTL flanked by markers bPb-1278 and bPb-8437 on chromosomes 4H was associated with TN, SPL, and SPP under salt stress. This locus may be useful in the breeding program of marker-assisted selection for improving salt tolerance of barley. However, QTLs associated with NA, K, and NAK differed greatly between non-stress and salt stress environments. It may be suggested that only the QTLs detected under salt stress are really associated with salt tolerance in barley.

In order to better understand the role of cold acclimation in alleviating freezing injury, two barley cultivars with different cold tolerance, i.e. a sensitive cv. Chumai 1 and a tolerant cv. Mo 103, were used. The freezing treatment increased leaf soluble protein content more in the tolerant cultivar than in the sensitive one. Cold acclimation increased H2O2 content of the two cultivars during freezing treatment, especially in Mo 103. Glutathione and ascorbate contents during freezing and recovery were significantly higher in cold-acclimated plants than in non-acclimated ones. Activities of peroxidase, ascorbate peroxidase and glutathione reductase were also higher in cold-acclimated plants than non-acclimated plants during freezing treatment. However, there was no significant difference between cold-acclimated plants and the control plants in catalase activity. It may be assumed that cold acclimation induced H2O2 production, which in turn enhanced activities of antioxidative enzymes and synthesis of antioxidants, resulting in alleviation of oxidative stress caused by freezing.

High malting quality of barley (Hordeum vulgare L.) relies on many traits, such as β-amylase and limit dextrinase activities and β-glucan and protein fraction contents. In this study, interval mapping was utilized to detect quantitative trait loci (QTLs) affecting these malting quality parameters using a doubled haploid (DH) population from a cross of CM72 (six-rowed) by Gairdner (two-rowed) barley cultivars. A total of nine QTLs for eight traits were mapped to chromosomes 3H, 4H, 5H, and 7H. Five of the nine QTLs mapped to chromosome 3H, indicating a possible role of loci on chromosome 3H on malting quality. The phenotypic variation accounted by individual QTL ranged from 8.08% to 30.25%. The loci of QTLs for β-glucan and limit dextrinase were identified on chromosomes 4H and 5H, respectively. QTL for hordeins was coincident with the region of silica eluate (SE) protein on 3HS, while QTLs for albumins, globulins, and total protein exhibited overlapping. One locus on chromosome 3H was found to be related to β-amylase, and two loci on chromosomes 5H and 7H were found to be associated with glutelins. The identification of these novel QTLs controlling malting quality may be useful for marker-assisted selection in improving barley malting quality.

Cadmium (Cd) is a non-essential element and toxic to plants. To investigate the genetics of Cd tolerance and accumulation in rice, quantitative trait loci (QTL) associated with Cd tolerance and accumulation at the seedling stage were mapped using a doubled haploid (DH) population derived from a cross between a japonica JX17 and an indica ZYQ8. A total of 22 QTLs were found to be associated with shoot height (SH), root length (RL), shoot dry weight (SDW), root dry weight (RDW), total dry weight (TDW) and chlorophyll content (CC), and 10 and 12 QTLs were identified under the control and Cd stress conditions, respectively. For Cd tolerant coefficient (CTC), 6 QTLs were detected on chromosomes 1, 3, 5, 8 and 10. Under Cd stress, 3 QTLs controlling root and shoot Cd concentrations were mapped on chromosome 6 and 7. One QTL for shoot/root rate of Cd concentration was identified on chromosome 3. The results indicated that Cd tolerance and accumulation were quantitatively inherited, and the detected QTLs may be useful for marker-assistant selection (MAS) and identification of the genes controlling Cd tolerance and accumulation in rice.

Difference in isozymes and activities of peroxidase (POD) and superoxide dismutase (SOD) in two barley (Hordeum vulgare L.) genotypes differing in salt tolerance (Gebeina, tolerant; Quzhou, sensitive) was investigated using a hydroponic experiment. The activities of both enzymes were significantly increased when the plants of the two barley genotypes were exposed to salt stress, with salt-tolerant genotype being generally higher than the sensitive one. The variation in the POD and SOD isozymes was dependent on barley genotype, salt level and exposure time. When the plants were exposed to salt stress for 10 days, two new POD isozymes were found, Rm0.26 (Rm, relative mobility of enzyme to dye) in Gebeina and Rm0.45 in Quzhou. Both isozymes disappeared after 20 days of salt stress, but Rm0.26 appeared again 30 days after the stress. Two new SOD isozymes of Rm0.19 and Rm0.46 were found in Gebeina when exposed to NaCl for 10 days, but only Rm0.46 in Quzhou. As the time of salt stress extended, more new SOD isozymes were detected, Rm0.35 in both genotypes in all different salt treatments and Rm0.48 in Gebeina under 200 mM NaCl stress. At 30 days after the stress, all the new SOD isozymes disappeared except for Rm0.48 in Gebeina under 200 mM NaCl stress. The results suggest that the increased POD and SOD activities could be partly due to the formation of some new isozymes and the tolerant variety had better ability to form new isozymes to overcome salt stress.

A hydroponic experiment was conducted to examine the effect of Cd stress on anti-oxidative enzyme activities at heading stage, yield components, root exudation and Cd and N uptake of rice plants grew in different N source i.e. (NH4)2SO4, NH4NO3 and Ca(NO3)2. The results show that the effect of Cd stress on all measured parameters were N source dependent. Cd stress (1 μM) caused a remarkable reduction in grain yield and shoot biomass, an increase in root exudation, glutathione content, Cd concentration and catalase (CAT) and peroxidase (POD) activities of rice plants. In the plants under the control (without Cd addition) N source had no distinctive effect on the above measured parameters, but the differences among the three N forms in these parameters became significant when plants were exposed to Cd stress. Cd stress significantly increased POD and CAT activities, and gultathione content, with Ca(NO3)2-fed plants having the greatest POD and CAT activities and lowest glutathione content, and (NH4)2SO4-fed plants being just opposite. Moreover, organic acid exudation varied also with N form for the Cd-stressed plants. In comparison with other two N forms, (NH4)2SO4,-treated plants had higher grain yield, N concentration and lower Cd concentration in plants. The current results indicated that (NH4)2SO4 is a better fertilizer for use in Cd contaminated soil.

To understand genetic patterns of the morphological and physiological traits in flag leaf of barley, a double haploid (DH) population derived from the parents Yerong and Franklin was used to determine quantitative trait loci (QTL) controlling length, width, length/width, and chlorophyll content of flag leaves. A total of 9 QTLs showing significantly additive effect were detected in 8 intervals on 5 chromosomes. The variation of individual QTL ranged from 1.9% to 20.2%. For chlorophyll content expressed as SPAD value, 4 QTLs were identified on chromosomes 2H, 3H and 6H; for leaf length and width, 2 QTLs located on chromosomes 5H and 7H, and 2 QTLs located on chromosome 5H were detected; and for length/width, 1 QTL was detected on chromosome 7H. The identification of these QTLs associated with the properties of flag leaf is useful for barley improvement in breeding programs.

We characterized yield-relevant characters and their variations over genotypes and environments (locations and years) by examining two rice varieties (9746 and Jinfeng) with high yield potential. 9746 and Jinfeng were planted in two locations of Shanghai, China, during 2005 and 2006. The results show that there was a large variation in grain yield between locations and years. The realization of high yield potential for the two types of rice was closely related to the improved sink size, such as more panicles per square meter or grains per panicle. Stem and leaf biomasses were mainly accumulated from tillering stage to heading stage, and showed slow decline during grain filling. Meanwhile, some photosynthetic characters including net photosynthesis rate (Pn), leaf area index (LAI), specific leaf area (SLA), fluorescence parameter (maximum quantum yield of PSII, Fv/Fm), chlorophyll content (expressed as SPAD value), as well as nutrient (N, P, K) uptake were also measured to determine their variations over genotypes and environments and their relationships with grain yield. Although there were significant differences between years or locations for most measurements, SLA at tillering and heading stages, Fv/Fm and LAI at heading stage, stem biomass at heading and maturity stages, and leaf nitrogen concentration at tillering and heading stages remained little changed, indicating their possible applications as selectable characters in breeding programs. It was also found that stem nitrogen accumulation at tillering stage is one of the most important and stable traits for high yield formation.

The influence of betaine aldehyde dehydrogenase (BADH) and salinity pretreatment on oxidative stress under cadmium (Cd) toxicity was investigated in rice cv. Xiushui 11 and its BADH-transgenic line Bxiushui 11. The results showed that plants previously treated with 4.25 and 8.5 mM NaCl, respectively, for 5 days each had higher Cd concentrations in both roots and shoots of the two rice genotypes compared with the controls. Malondialdehyde (MDA) content in both leaves and roots was increased by salinity pretreatment and was significantly lower in the salinity-pretreatment plants than in the controls when the plants were consequently exposed to Cd stress. Salinity pretreatment also increased proline content and the activities of superoxide dismutase (SOD) and peroxidase (POD) in both leaves and roots. It can be assumed that salinity pretreatment enhances the defensive ability of plants against oxidative stress through increasing activities of antioxidative enzymes. The BADH-transgenic line (Bxiushui 11) had lower Cd and MDA content, higher SOD and POD activities, and higher proline content than its wild type (Xiushui 11). The current results suggest that betaine, a product of BADH expression, improves the tolerance of rice plants to Cd stress through increasing the activities of antioxidative enzymes and osmoprotectant content.

Phytic acid or phytate is a chelating agent, which is involved in binding minerals (such as K+, Ca2+, Zn2+, Fe2+, etc.) and making them unavailable for dietary absorption. It is also involved in forming complexes with protein, making protein less soluble, and affecting enzymatic degradation, gastric absorption, and malting processes. The phytic acid and protein contents of barley grains are influenced by genetic and environmental factors. This study investigated differences in phytic acid and protein contents in grains of 100 barley (Hordeum vulgare L.) genotypes or cultivars. Eight barley cultivars were selected and grown at seven locations for two years to study the effects of genotypic and environmental factors on phytic acid content (PAC) and its relation to malt quality. The phytic acid contents of 100 barley genotypes ranged from 3.85 mg g−1 to 9.85 mg g−1, with a mean of 7.01 mg g−1. The effects of cultivars, locations, time and their interactions were highly significant, but the variation was mainly attributed to the environment (location and time). The correlation between grains phytic acid and protein content was significant and positive. Whereas, the correlation between grain phytic acid content and malt extract was significant and negative. The relationship between phytic acid and protein contents of barley is important as it affects the malting process, malt yield and quality, and final beer quality. Barley grain for malting and feed uses should have low phytic acid content.

The effect of Al and Cd on the growth, photosynthesis, and accumulation of Al, Cd and plant nutrients in two soybean genotypes were determined using hydroponic culture. There were six treatments: pH 6.5; pH 4.0; pH 6.5+1.0 μmol/L Cd; pH 4.0+1.0 μmol/L Cd; pH 4.0+150 μmol/L Al; pH 4.0+1.0 μmol/L Cd+150 μmol/L Al. The low pH (4.0) and Al treatments caused marked reduction in root length, shoot height, dry weight, chlorophyll content (SPAD value) and photosynthetic rate. Al-sensitive cv. Zhechun 2 accumulated comparatively more Al and Cd in plants than Al-tolerant cv. Liao 1. Compared with pH 6.5, pH 4.0 resulted in significant increase in Cd and Al concentration in plants. Combined application of Cd and Al enhanced their accumulation in roots, but caused a reduction in shoots. The concentrations of all 10 nutrients (P, K, Ca, Mg, Fe, Mn, Cu, Zn and B), except Mo were also increased when plants were exposed to pH lower than pH 6.5. Al addition caused a reduction in the concentration of most nutrients in plant roots and shoots; but K, Mn and Zn in roots were increased. Treatments with Cd alone or together with Al reduced the concentrations of all the plant nutrients in plants. Al-sensitive genotype Zhechun 2 has lower nutrient concentration than Al-tolerant genotype Liao 1. The current findings imply that Al and Cd are synergistic in their effect on plant growth, physiological traits and nutrient uptake.

Interaction of salinity (NaCl) and cadmium (Cd) on growth, mineral nutrients, Na and Cd accumulation in four barley genotypes differing in salt tolerance was studied in a hydroponic experiment. Cd, NaCl and their combined stresses reduced Ca and Mg concentrations in roots and shoots, K concentration in shoots, increased K and Cu concentrations in roots relative to control, but had non-significant effect on micronutrients Cu, Fe and Mn concentrations in shoot. The three stresses reduced accumulation of most tested nutrients in both roots and shoots, except NaCl and NaCl+Cd stresses for root K and shoot Cu accumulation in salt tolerant genotypes. The salt tolerant genotypes did not have higher nutrient concentration and accumulation than the sensitive ones when exposed to Cd and NaCl stresses. In conclusion, the affecting mechanism of Cd stress on nutrients was to some extent different from salinity stress, and the NaCl+Cd stress was not equal to additional Cd and NaCl stresses, probably due to the different valence and competitive site of Na+ and Cd2+. NaCl addition in the Cd-containing medium caused remarkable reductions in both Cd concentration and accumulation, with the extent of reduction being also dependent on genotypes. The salt-tolerant genotypes had lower Na concentration than sensitive ones.

The effects of salinity (50 mmol/L NaCl) and Cd (1 μmol/L CdCl2) as sole and combined on growth and photosynthetic parameters were studied using two soybean genotypes, Huachun 18 and NGB. The concentrations of Cd2−, Zn2−, Ca2+, Mg2+, K+ and Na+ were also determined in seeds and pods. Huachun 18 suffered a more serious decrease than NGB in net photosynthetic rate (Pn) in the treatments of salinity stress alone and combined stress (NaCl+Cd), showing that it is relatively sensitive to salinity. The decrease in Pn caused by salt stress in Huachun 18 was mainly due to the reduced total chlorophyll content and photosynthetic efficiency (the ratio of variable fluorescence to maximal fluorescence, Fv/Fm), whereas the decrease in NGB was mainly related to reduced stomatal conductance (Gs). The combined stress of both Na and Cd did not induce further decrease in photosynthesis and fluorescence in the two genotypes relative to salt or Cd stress alone. Greater change in the pod concentrations of Zn2+, Ca2+, Mg2+, K+ and Na− was detected under salt stress for Huachun 18 than for NGB. The results suggested that the interactive effect of NaCl-Cd on growth and nutrient uptake differs between the two soybean genotypes.

High iron levels in rice soils represent a major problem for seedling establishment and crop growth, and rapid coleoptile elongation is the mechanism for the rice to cope with the induced stress. Quantitative trait loci (QTLs) analysis for coleoptile elongation rate (CER) in rice (Oryza sativa L.) was performed to study the inheritance of CER and its response to Fe nutrition. A recombinant inbred line (RIL) population of 244 lines derived from the cross zhenshan97B/miyang46 was germinated in 2004 under four Fe concentrations (0, 1.79, 7.16, and 14.32 mM). Seven QTLs with additive effects of stimulating CER were detected under the four Fe concentrations and they were localized on chromosome 1, 4, 5 and 7 with LOD ranging from 2.88 to 15.94 and their contribution to total phenotypic variance ranging from 4.17% to 15.87%, respectively. In addition, 21 QTLs with additive × additive epistasis were detected on all chromosomes but 4 and 9. The detected QTLs with additive effect mainly came from the male parent ZS97B. The detected number of QTLs with additive and epistatic effects for CER varied with Fe concentration. An additive QTL with G × Fe effect was detected between RZ460 and RZ730 markers of chromosome 1 using multi-environmental model of QTL Mapper 1.6 and considering Fe concentration as an environmental factor. The pattern of CER in the different Fe concentrations was well characterized by the genetic model of quantitative traits. It was found that some RILs had higher CER than both parents in each Fe concentration.

The experiment was conducted to investigate the formation of oxidative stress and the development of anti-oxidative enzymes in two barley genotypes differing in anoxia tolerance. Waterlogging led to significant reduction in root and shoot weight, green leaf area and tillers per plant, but tolerant Xiumai 3 was much less reduced than sensitive Gerdner. Malondialdehyde (MDA) content, an indicator of membrane lipid peroxidation, significantly increased in Gerdner when the plants were subjected to waterlogging, but remained little changed in Xiumai 3. Superoxide dismutase (SOD) activity was increased with waterlogging treatment and the sensitive cultivar had higher activity than the tolerant one during the experimental duration. At early stage of waterlogging treatment, both peroxidase (POD) and catalase (CAT) activities significantly increased in Xuimai 3, while obviously decreased in Gerdner. Moreover, both cultivars showed substantial increase in both POD and CAT with the progress of waterlogging exposure. Glutathione reductase (GR) activity was increased in both tolerant- and sensitive cultivars under waterlogging. It may be assumed from the current results that SOD activity appears to be not a constraining factor limiting the scavenging of ROS, and it is the change of POD and CAT activity under waterlogging that determine the status of oxidative stress. The difference between genotypes in waterlogging tolerance could be distinguished from the changed patterns of these enzymatic activities.

The effect of iron (Fe) nutrition on cadmium (Cd) toxicity and accumulation in rice plants was studied using a hydroponic system. The inhibitory effect of Cd on plant growth and chlorophyll content (SPAD value) was dependent on Fe level and the genotype. Malondialdehyde (MDA) content in leaves and roots was not much affected by an increased Cd stress at 0.171 mg l−1 Fe, but it showed a rapid increase when the plants were exposed to moderate (1.89 mg l−1) and high (16.8 mg l−1) Fe levels. High Fe nutrition caused a marked reduction in Cd content in both leaves and roots. Fe content in plants was lower at high Cd (5.0 μM) stress than at low Cd (<1.0 μM) stress. Cd stress increased both superoxide dismutase (SOD) and peroxidase (POD) activities at low and moderate Fe levels. However, with high Fe level, it increased the POD activity, but reduced the SOD activity. Our results substantiate the hypothesis that cell membrane-bound iron transporter (carrier) involved in high-affinity iron transport systems can also transport Cd, and both these ions may compete for this common carrier. The study further showed that there were significant correlations between MDA and Fe contents in leaves and roots of rice plants. It is suggested that the occurrence of oxidative stress in plants exposed to Cd stress is mediated by Fe nutrition. The present results also show that Cd stress affects the uptake of Cu and Zn.

Differences in cooking and eating properties between chalky and translucent parts of rice grains were investigated in samples from six indica rice varieties with different palatabilities. A differential scanning calorimeter (DSC), rapid visco analyzer (RVA) and texture analyzer were employed for determining physicochemical parameters, which were used as indirect indicators of cooking and eating quality. The results showed that the chalky part in milled rice had a dramatically higher transition temperature (To, Tp, Tc) and ΔH than the translucent part and the difference was much larger than that among varieties. Meanwhile, the chalky part had lower GC, SP and higher hardness than the translucent part, while there were slight or little differences in RVA properties and AC between the two parts. It may be suggested that the higher transition temperature and ΔH associated with higher chalky occurrence are major cause of deteriorated cooking quality due to increased energy requirement for gelatinization, in addition to the adverse effect of chalk occurrence on the visual appearance of rice.

The cultivar and environmental variations of β-glucan content and β-glucanase activity in grains and malt were investigated in 8 barley cultivars grown at 7 locations. On average, for all cultivars and locations, approximately 80% of β-glucan present in grains was degraded after malting, but there was great variation among both cultivars and locations. β-glucanase activity was much lower but detectable in grains, and it dramatically increased after malting. The cultivar and environmental variations of β-glucan content were much higher in malt than in grains, and malt β-glucan content was more dependent on malt β-glucanase activity than the original level of β-glucan in grains. The correlation analysis of β-glucan content, β-glucanase activity and four malt quality parameters (Kolbach index, diastatic power, viscosity and malt extract) showed that malt-glucan content was highly significantly correlated with all quality parameters, while the association between grain β-glucan content and these quality parameters was relatively weak. Malt β-glucan content was negatively and highly significantly correlated with malt β-glucanase activity, and positively and significantly correlated with grain β-glucan content. It was also found that there was a positive and significant correlation between grain and malt β-glucanase activity.

β-Amylase activities of barley cultivars collected from various areas of China, and as well as from Canada and Australia, were assayed. Meanwhile a multi-location trial was conducted to determine variation of β-amylase activity in eight barley cultivars and the relationship between β-amylase activity and protein content. For 56 cultivars in study, β-amylase activity ranged from 458 to 1024 U/g, with a mean of 738 U/g. There was significant variation in both β-amylase activity and protein content for eight barley cultivars grown in four locations. No significant correlation was found betweenβ-amylase activity and protein content surveyed in 56 cultivars.

β-glucan content of barley cultivars collected from various areas of China, as well as from Canada and Australia, were assayed by an enzymatic method. Meanwhile a multi-location trial was conducted to determine β-glucan content of eight barley cultivars in each location. For 164 cultivars, originating from China, β-glucan content ranged from 2.98% for Sumei 21 to 8.62% for QB25, with a mean of 4.58%. Tibet barleys, all of the hull-less type, had the highest β-glucan content. Winter barley cultivars from various areas of China had basically the same β-glucan content as those from Canada and Australia. The seeds produced in Hangzhou had lower β-glucan contents than those produced locally. The effects of cultivars, environments (locations) and their interactions on β-glucan content variation was all highly significant, with the cultivars having the largest effect. The highly significant interaction between cultivars and environment suggests that it is important to plant the appropriate cultivar in a particular area in order to obtain barley seeds with reasonable β-glucan contents.

Cadmium (Cd) accumulation and toxicity in rice plants were characterized and identified by using brittle culm 1 (bc1), a fragile rice mutant and its wild type (Shuangkezao, an indica rice) as materials by hydroponics. The low Cd level didn't obviously affect the growth parameters in both rice genotypes, but under high Cd levels (1.0 and 5.0 μmol/L), the growth of both rice plants were substantially inhibited. Moreover, bc1 tended to suffer more seriously from Cd toxicity than Shuangkezao. Cd accumulation in both rice plants increased with the increase of Cd levels. There was a significant difference in Cd accumulation between the two rice genotypes with constantly higher Cd concentration in bc1, which also accumulated more Cd at 0, 0.1, and 1.0 μmol/L Cd levels. The same case was found in the two rice plants grown on Cd-contaminated soil. This suggested that cell wall might play an important role in Cd accumulation in rice plants by the physiological mechanisms. The malondialdehyde (MDA) content, superoxide dismutase (SOD) and peroxidase (POD) activities in rice plants were affected differently under Cd treatments, and which implied that POD might play the main role in detoxifying active oxygen free radical. A significant difference in antioxidative system between the two rice genotypes was found with constantly higher MDA content, SOD and POD activities in bc1. In summary, bc1 accumulated more Cd and appeared to be more sensitive to Cd stress compared with its wild type.

A pot experiment was conducted to study the hormonal changes during the grain filling stage in barley lines of Triumph and its mutant TL43 with or without nitrogen fertilizer at heading time. The ABA, ZR and IAA contents in grains were higher under nitrogen treatment (HN) for both genotypes at 30 days post anthesis (DPA). No genotypic differences were observed in GA3, ABA and IAA content over the grain filling stage and ZR content on 10 DPA exhibited the major difference, which might be associated with the decrease of A-type starch granules in endosperm of TL43. Triumph also showed significantly higher grain weight, lower hordein and glutelin contents than TL43. The changes of these characters might be correlated with the ZR deficiency of TL43 at early grain filling stage.

The field experiments were conducted to investigate the growth and physiological responses of six super hybrid rice combinations to two planting methods, transplanting (TP) and direct seeding (DS) during 2006–2007 and 2007–2008. The 1000-grain weight and number of tillers per plant at the early growth stage, the maximum quantum yield of PSII (Fv/Fm) and transpiration rate (Tr) were higher in DS plants than in TP ones, whereas the grain yield, number of panicles per square meter, seed setting rate, net photosynthetic rate (Pn) and stomatal conductance were lower in DS plants. However, little difference was detected in number of grains per panicle, stem (shoot) and leaf weight between the combinations in the two planting methods. The responses of plant growth and physiological traits to planting method differed greatly among the six combinations. In both planting methods, Chouyou 58 and Yongyou 6 had the highest and lowest panicle biomass and Pn, respectively. The higher yield of Chunyou 58 was associated with more numbers of panicles per square meter and grains per panicle in both planting methods. The results indicate that lower grain yield in DS relative to TP is attributed to more excessive tillers at the early stage, lower leaf biomass and photosynthetic rate at the late stage.

A japonica variety and its iso-allelic mutant with high tillering ability were used to investigate the differences in grain yield and quality among different tillers. There was a distinct difference in panicle weight among tillers during grain filling for both genotypes, with Xiushui 11 having a greater increase rate in panicle weight, and being earlier in reaching the maximum panicle weight than the mutant. There was a great significant difference between the two genotypes in grain yield and its components, with Xiushui 11 having higher grain yield, more grains per panicle, higher filled grain percentage and grain weight than the mutant for each type of tiller. Moreover, a significant difference was found in grain yield and yield components among different tillers for both genotypes, with grain number per panicle showing the greatest variation over tillers among all yield components. Compared with Xiushui 11, the mutant had higher brown rice rate and greater ratio of length to width of brown rice, and lower chalky rice rate, amylose content, and protein content of rice. Furthermore, there was a significant difference in grain quality among tillers within a plant for both genotypes, with later initiated tillers being lower in chalky rice rate, amylose and protein contents than early initiated ones. The variation of most quality parameters among tillers within a plant was markedly larger for the mutant than for Xiushui 11.

The variation of amylose content (AC) among grains within a panicle and its relation to panicle morphology were investigated using 44 japonica rice cultivars differing in grain density (GD), panicle bending degree (BD) and palatability. Morphological traits of the rice panicle were poorly associated with mean grain AC on the average of the whole panicle, but closely related to AC variation and spatial distribution within a panicle, with the compact-panicle cultivars (GD>6.5 grain/cm and BD< 30°) having greater variation than loose-panicle cultivars (GD<6.0 grain/cm and BD>70°). The extent of AC differences among the rachides within a panicle was also cultivar-dependent, and greater differences were found between middle and top rachides for the compact-panicle cultivars, and between middle and bottom rachides for the loose-panicle cultivars. The difference in spatial distribution of AC variation between Bing110 (a compact-panicle cultivar) and XS11 (a loose-panicle cultivar) indicated that grains with low AC were principally distributed on interior rachis of middle branches for Bing110, but on bottom-rachis for XS11. Such a distribution is basically associated with the difference in the timing procedure of floret initiation and development, and final grain weight.

Development of the new crop cultivars with high yield under low nitrogen (N) input is a fundamental approach to enhance agricultural sustainability, which is dependent on the exploitation of the elite germplasm. In the present study, four barley genotypes (two Tibetan wild and two cultivated), differing in N use efficiency (NUE), were characterized for their physiological and biochemical responses to different N levels. Higher N levels significantly increased the contents of other essential nutrients (P, K, Ca, Fe, Cu and Mn), and the increase was more obvious for the N-efficient genotypes (ZD9 and XZ149). The observation of ultrastructure showed that chloroplast structure was severely damaged under low nitrogen, and the two high N efficient genotypes were relatively less affected. The activities of the five N metabolism related enzymes, i.e., nitrate reductase (NR), glutamine synthetase (GS), nitrite reductase (NiR), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) all showed the substantial increase with the increased N level in the culture medium. However the increased extent differed among the four genotypes, with the two N efficient genotypes showing more increase in comparison with the other two genotypes with relative N inefficiency (HXRL and XZ56). The current findings showed that a huge difference exists in low N tolerance among barley genotypes, and improvement of some physiological traits (such as enzymes) could be helpful for increasing N utilization efficiency.

Improvement of malt quality is the most important objective in malt barley breeding. The current experiments investigated the variation of malt quality characters among barley genotypes and the difference in genetic variants of HvGlb1, encoding β-glucanase isoenzyme I, between Tibetan annual wild barley and cultivated barley. The correlation between the gene variants and malt quality showed that there was a large difference in the four malt quality parameters, i.e. Kolbach index, diastatic power (DP), viscosity and malt extract, among the analyzed barley cultivars. Kolbach index was negatively and positively correlated with viscosity and malt extract, respectively, while malt extract was negatively correlated with viscosity. Malt β-glucan content was a major determinant of malt quality, and was significantly correlated with Kolbach index (−0.633), malt extract (−0.333) and viscosity (0.672). On the other hand, malt β-glucan content was mainly controlled by malt β-glucanase activity. The correlation analysis showed that the HvGlb1 gene was correlated with malt β-glucan content and three of four main malt quality parameters, except DP. In addition, we also found that the HvGlb1 of Tibetan barley had wider diversity in haplotype than that of the cultivated barley, supporting the hypothesis that Tibet is one of the original centers of cultivated barley.

•Some Tibetan wild barley accessions showed the high low nitrogen tolerance.•Low-nitrogen tolerant wild barley XZ149 had more N transportation from roots to leaves under LN stress.•XZ49 also showed relatively higher activities of nitrate reductase and glutamine synthetase in leaves under LN stress.•XZ149 remained less change in P, K, Ca, Mn and Cu contents in roots than XZ56 and ZD9 under LN stress.In a previous study, we identified the low-nitrogen (LN) tolerant accessions from the Tibetan wild barley (Hordeum vulgare subsp. spontaneum). In this study, two wild barley genotypes (XZ149, LN-tolerant and XZ56, LN-sensitive) and a barley cultivar ZD9 (H. vulgare) were used to determine the LN tolerant mechanism underlying the wild barley in the ionomic and physiological aspects. XZ149 exhibited higher LN tolerance with highest relative dry weight and N accumulation among three barley genotypes under LN stress. When exposed to LN stress, XZ149 had more N transportation from roots to leaves, and remained relatively higher activities of nitrate reductase (NR, EC.1.7.1.1) and glutamine synthetase (GS, EC.6.3.1.2) in leaves than other two genotypes, ensuring its higher capacity of N assimilation and utilization. The ionome analysis showed that LN stress had a significant effect on tissue ionome and the effect was genotypic and tissue-specific difference. On the whole, XZ149 maintained more stable Mn and Cu contents in roots, and less reduction of root P, K and Ca contents than XZ56 and ZD9 when exposed to LN stress. It may be assumed that more N movement into shoots, greater N assimilating capacity and specific rearrangement of nutrient element levels in tissues under LN stress are attributed to LN tolerance in XZ149.

A study was conducted to determine the influence of no-tillage cultivation on leaf photosynthesis of rice plants under field conditions. Experiments with the treatments, no-tillage and conventional tillage were carried out at three locations (Jiaxing, Hangzhou, and Xiaoshan, Zhejiang Province, China) for two years (2005 and 2006). Grain yield was constant in Jiaxing, but slightly higher in Hangzhou and Xiaoshan under no-tillage cultivation than that under conventional cultivation. In comparison with the conventional cultivation, no-tillage cultivation showed less biomass accumulation before heading and higher capacity of matter production during grain filling. A significantly higher leaf net photosynthetic rate was observed for the plants under no-tillage than for those under conventional tillage. The fluorescence parameter (Fv/Fm) in leaf did not show any difference between the two cultivations. The effect of cultivation management on transpiration rate (Tr) and SPAD value of rice leaf was dependent on the location and year.

Arabinoxylan (AX) content in barley grains is an important quality determinant when barley is used as raw material of malt or beer production. The cultivar and environmental variations of total arabinoxylan (TAX), water extractable arabinoxylan (WEAX) and endoxylanase activity (EA) were investigated using eight barley cultivars growing at seven locations with diverse environmental conditions. The results showed that both barley cultivar and location significantly affected the TAX, WEAX and EA levels, but the variations of TAX content and EA were mainly attributed to cultivar, while the impact of location on WEAX content was greater than that of cultivar. Correlation analysis indicated that TAX was significantly correlated to WUAX.

A hydroponic experiment was carried out to study the effect of aluminum (Al) and cadmium (Cd) on Al and mineral nutrient contents in plants and Al-induced organic acid exudation in two barley varieties with different Al tolerance. Al-sensitive cv. Shang 70-119 had significantly higher Al content and accumulation in plants than Al-tolerant cv. Gebeina, especially in roots, when subjected to low pH (4.0) and Al treatments (100 μmol L−1 Al and 100 μmol L−1 Al +1.0 μmol L−1 Cd). Cd addition increased Al content in plants exposed to Al stress. Both low pH and Al treatments caused marked reduction in Ca and Mg contents in all plant parts, P and K contents in the shoots and leaves, Fe, Zn and Mo contents in the leaves, Zn and B contents in the shoots, and Mn contents both in the roots and leaves. Moreover, changes in nutrient concentrations were greater in the plants exposed to both Al and Cd than in those exposed only to Al treatment. A dramatic enhancement of malate, citrate, and succinate was found in the plants exposed to 100 μmol L−1 Al relative to the control, and the Al-tolerant cultivar had a considerable higher exudation of these organic acids than the Al-sensitive one, indicating that Al-induced enhancement of these organic acids is very likely to be associated with Al tolerance.

The effect of exogenous reduced glutathione (GSH) on alleviation of hexavalent chromium (Cr6+) toxicity to rice seedlings and its physiological mechanisms were comprehensively investigated in a series of experiments. Our results showed that growth and nutrient uptake of rice seedlings were dramatically reduced under 100 μM Cr6+ stress, and the reduction was significantly alleviated by exogenous GSH. Cr6+ stress also reduced cell viability in root tips and damaged ultrastructure of both chloroplasts and root cells, while the addition of GSH alleviates those negative effects. Cr-induced toxicity and GSH-caused Cr alleviation differed significantly between Cr-tolerant Line 117 (L117) and Cr-sensitive Line 41 (L41). Under Cr6+ stress, cystine content was increased and GSH content was decreased in rice plants, exogenous GSH, however, mitigated the Cr-toxicity by reversing the Cr-induced changes of the two compounds. The types of Cr-induced secretion of organic acids varied between the genotypes, where reduction in the contents of acetic and lactic acids and tartaric and malic acids were observed in L117 and L41, respectively. The addition of GSH alleviated the reduction of secretion of these organic acids. Exogenous GSH also altered the forms of Cr ions in the rhizosphere and the fraction of distribution at subcellular level in both shoots and roots. It may be concluded that the alleviation of Cr6+ toxicity by exogenous GSH is directly attributed to its regulation on forms of Cr ions in rhizosphere and their distribution at subcellular levels.

•The regression models of total phenolics and p-coumaric acid could be improved by pre-treating NIRS data.•Least squares support vector machine model made a better performance for total phenolics and p-coumaric acid.•All the calibration models provided powerful predictive capacity for total phenolics and p-coumaric acid.Barley grains are rich in phenolic compounds, which are associated with reduced risk of chronic diseases. Development of barley cultivars with high phenolic acid content has become one of the main objectives in breeding programs. A rapid and accurate method for measuring phenolic compounds would be helpful for crop breeding. We developed predictive models for both total phenolics (TPC) and p-coumaric acid (PA), based on near-infrared spectroscopy (NIRS) analysis. Regressions of partial least squares (PLS) and least squares support vector machine (LS-SVM) were compared for improving the models, and Monte Carlo-Uninformative Variable Elimination (MC-UVE) was applied to select informative wavelengths. The optimal calibration models generated high coefficients of correlation (rpre) and ratio performance deviation (RPD) for TPC and PA. These results indicated the models are suitable for rapid determination of phenolic compounds in barley grains.

Nitrogen (N) is an essential macronutrient for plants. The increasingly severe environmental problems caused by N fertilizer application urge alleviation of N fertilizer dependence in crop production. In previous studies, we identified the Tibetan wild barley accessions with high tolerance to low nitrogen (LN). In this study, metabolic analysis was done on two wild genotypes (XZ149, tolerant and XZ56, sensitive) to understand the mechanism of LN tolerance, using a hydroponic experiment. Leaf and root samples were taken at seven time points within 18 d after LN treatment, respectively. XZ149 was much less affected by low N stress than XZ56 in plant biomass. A total of 51 differentially accumulated metabolites were identified between LN and normal N treated plants. LN stress induced tissue-specific changes in carbon and nitrogen partitioning, and XZ149 had a pattern of energy-saving amino acids accumulation and carbon distribution in favor of root growth that contribute to its higher LN tolerance. Moreover, XZ149 is highly capable of producing energy and maintaining the redox homeostasis under LN stress. The current results revealed the mechanisms underlying the wild barley in high LN tolerance and provided the valuable references for developing barley cultivars with LN tolerance.

Low phosphorus (LP) in soil is a widely-occurred limiting factor for crop production in the world. In a previous study we identified a highly LP-tolerant Tibetan wild barley accession (XZ99). Here, a comparatively proteomic analysis was conducted using three barley genotypes differing in LP tolerance to reveal the mechanisms underlying the LP tolerance of XZ99. Totally, 31 differentially accumulated proteins were identified in the roots and leaves of the three genotypes using 2-dimensional gel electrophoresis coupled with mass spectrometry. They were involved in the various biological processes, including carbon and energy metabolism, signal transduction, cell growth and division, secondary metabolism, and stress defense. In comparison with XZ100 (LP sensitive) and ZD9 (LP moderately-tolerant), XZ99 had a more developed root system, which is mainly attributed to enhanced carbohydrate metabolizing proteins under LP conditions. The current results showed that Tibetan wild barley XZ99 and cultivated barley cultivar ZD9 differ in the mechanism of LP tolerance. The changes of the proteins associated with carbohydrate metabolism could account for the difference between the LP-tolerant and LP-sensitive genotypes. In addition, the mRNA expression levels of 9 LP responsive proteins were verified by qRT-PCR. The current results may open a new avenue of understanding the LP tolerance in plants on the proteomic basis.