This research was designed to assess the changes in anthocyanin content in grape skins of Vitis amurensis and to explore mRNA transcriptions of 11 structural genes (PAL, CHS3, CHI1, F3H2, F3′H, F3′5′H, DFR, LDOX, UFGT, OMT and GST) related to anthocyanin biosynthesis during grape berry development, by the use of HPLC-MS/MS and real-time Q-PCR analysis. Accumulation of anthocyanins began at veraison, continued throughout the later berry development and reached a peak at maturity. Veraison is the time when the berries turn from green to purple. Expression of PAL, CHI1, and LDOX were up-regulated from 2 to 4 weeks after flowering (WAF), down-regulated from 6 WAF to veraison, whereas DFR was up-regulated at 8 WAF, and then up-regulated from veraison to maturity. CHS3, F3′5′H, UFGT, GST, and OMT were down-regulated from 2 WAF to veraison, and then up-regulated from veraison to maturity. The transcriptional expressions of the 11 structural genes also showed positive correlations with the anthocyanin content from veraison to maturity. Positive correlations were also observed between OMT transcriptional level and the content of methoxyl-anthocyanins, and between F3′5′H transcriptional level and the content of delphinidin anthocyanins. F3H2 and F3′H expression was up-regulated at 2 WAF. F3H2 expression was down-regulated from 4 WAF to veraison and then up-regulated again from veraison to maturity. F3′H expression was down-regulated at 4 WAF and then up-regulated again from 6 WAF to maturity. F3′H transcriptional level was correlated positively with the cyanidin anthocyanin concentration from veraison to maturity. These results indicate that the onset of anthocyanin synthesis during berry development coincides with a coordinated increase in the expression of a number of genes in the anthocyanin biosynthetic pathway.

•M-VSP and F-TT training reduce the level of unsaturated fatty acids in grapes.•M-VSP and F-TT training overall promoted C6 volatiles in grapes.•M-VSP and F-TT training enhance the level of C6 esters with fruity odor in wines.•The accumulation of C6 compounds is related to VvHPL1 and VvLOXA.C6 and C9 volatiles, originated from fatty acids, are important volatiles for ‘Cabernet Sauvignon’ grapes and wines. This study evaluated the influence of different training systems including Modified Vertical Shoot Positioned, (M-VSP); Fan training system with two trunks (F-TT); Fan training system with multiple trunks (F-MT) on these volatiles and the long-chain fatty acids (>C12) of grape berries and wines in the northwest of China. The expression profiles of genes from associated metabolic pathway were also analyzed. F-MT training resulted in lower vine vigor, larger yield, higher content of unsaturated fatty acids in grapes and lower C6 esters in wines in comparison with M-VSP and F-TT. M-VSP and F-TT enhanced C6 volatiles in grape berries. The concentrations of C6 volatiles were positively correlated with the expression of VvLOXA and VvHPL1. The results expanded the knowledge of the influence of training systems on fatty acids and their derived volatiles of grapes and wines.

Vitis amurensis var. Zuoshanyi is a native red variety grown in Northeast China with excellent cold hardness for genetic breeding and winemaking potential, but the volatiles profile, especially key compounds related to aroma character, was not fully revealed. In this work, Zuoshanyi grapes were collected across two harvests (2010 and 2011) in Shangzhuang area in Beijing, China. Free and glycosidase enzymatic hydrolysis volatiles were analyzed using SPME coupled with gas chromatography and mass spectrometry. A total of 135 volatile compounds were identified and quantified. Among the 13 categories of constituents, C6 compounds were the most abundant, followed by alcohols and ketones, and esters were the least abundant in two vintages. C6/C9 compounds, MPs (3-isobutyl-2-methoxypyrazine and 3-isopropyl-2-methoxypyrazine) and (E)-β-damascenone were the major compounds of Zuoshanyi grapes, which contributed “grass, green, fruit, etc.,” aroma as characterization of this distinctive cultivar. Results from hierarchical clustering and heatmap visualization revealed the accumulation patterns of volatile compounds during berry development. Principal component analysis showed clear separation of free and enzyme-released components in two vintages. Rainfall was the major different climate factor in log phase and before veraison of Zuoshanyi grapes in two vintages, and this difference may potentially influence the volatile variances of Zuoshanyi grapes.

•A gene encoding Va5GT glucosyltransferase from V. amurensis was cloned and the recombinant protein was expressed in E. coli.•The enzymatic properties (substrate specificity and enzyme kinetics) of Va5GT were established.•The previously speculated subcellular location of 5GTs in the cytoplasm was confirmed.•Transcriptional expression of Va5GT in related V. amurensis cultivars was analyzed.Generally, red Vitis vinifera grapes only contain monoglucosidic anthocyanins, whereas most non-vinifera red grapes of the Vitis genus have both monoglucosidic and bis-glucosidic anthocyanins, the latter of which are believed to be more hydrophilic and more stable. Although previous studies have established the biosynthetic mechanism for formation of monoglucosidic anthocyanins, less attention has been paid to that of bis-glucosidic anthocyanins. In the present research, the full-length cDNA of UDP-glucose: anthocyanin 5-O-glucosyltransferase from Vitis amurensis Rupr. cv. ‘Zuoshanyi’ grape (Va5GT) was cloned. After acquisition and purification of recombinant Va5GT, its enzymatic parameters were systematically analyzed in vitro. Recombinant Va5GT used malvidin-3-O-glucoside as its optimum glycosidic acceptor when UDP-glucose was used as the glycosidic donor. Va5GT-GFP was found to be located in the cytoplasm by analyzing its subcellular localization with a laser-scanning confocal fluorescence microscope, and this result was coincident with its metabolic function of modifying anthocyanins in grape cells. Furthermore, the relationship between the transcriptional expression of Va5GT and the accumulation of anthocyanidin bis-glucosides during berry development suggested that Va5GT is a key enzyme in the biosynthesis of bis-glucosidic anthocyanins in V. amurensis grape berries.UDP-glucose: anthocyanin 5-O-glucosyltransferase from Vitis amurensis grapes (Va5GT), which catalyzes the glucosylation of anthocyanidin monoglucosides at the 5-O-position, is crucial for the biosynthesis of anthocyanidin bis-glucosides.

•This research provides the first identification of bound volatiles in sweet cherry.•Alcohols and terpenes were the predominant components of bound volatiles.•Benzyl alcohol, geraniol, 2-phenylethanol are the major bound volatile constituents.•4-Vinylphenol was found in cherries for the first time.This paper reports the occurrence of both free and glycosidically bound aroma compounds in three sweet cherry cultivars (‘Hongdeng’, ‘Hongyan’ and ‘Rainier’), with 97 compounds being identified in the three cultivars. The major free volatile compounds found were hexanal, (E)-2-hexenal, (E)-2-hexen-1-ol, benzyl alcohol and benzaldehyde. The major bound volatile compounds found were benzyl alcohol, geraniol, 2-phenylethanol. Also 4-vinylphenol was found in cherry fruit for the first time, and has a relatively high concentration of the glycosidically-bound form in ‘Rainier’. Odour activity values (OAVs) were determined for both free and bound volatiles, with 18 compounds having an OAV above 1. The highest OAVs for three cultivars were (E)-β-ionone, hexanal, decanal and (E)-2-hexenal with the highest being over 800 for (E)-β-ionone in ‘Honyang’. From these results, it was concluded that the aroma compounds present were similar in all three cultivars, but there was significant variation found in their levels and hence contribution to the aroma of these cultivars.

The downstream flux of carotenoid metabolism in grape berries includes the biosynthesis of norisoprenoids, a group of important aroma compounds, and the production of ABA, a well-known plant hormone. This study focused on the transcriptional profiling comparison of genes participating in the biosynthesis of carotenoids, norisoprenoids, and ABA in Vitis vinifera ‘Cabernet Sauvignon’ grapes at pea size, veraison, and ripening stages. The grapes were obtained from Changli (CL, eastern China) and Gaotai (GT, western China) regions and analyzed using RNA-sequencing technology. The transcripts required for the carotenoid biosynthesis pathway showed a coordinated expression pattern, mainly expressing at green stage for CL and at veraison for GT, respectively. However, the carotenoid content evolution was not coincident with the timing and pattern of related gene expressions, since more carotenoids were accumulated at veraison in CL relative to two weeks before veraison in GT. Interestingly, norisoprenoid content was higher in GT than in CL, particularly at veraison and ripening, while the key gene encoding carotenoid cleavage dioxygenases, VvCCD1, showed an inverse relationship within the two regions. Higher flux was expected through the carotenoid pathway into ABA production in GT, based on the higher expression level of 9-cis-epoxycarotenoid dioxygenase and drought growing conditions. Most components involved in ABA and ethylene signaling showed distinct expression profiles in the two regions. These results revealed that downstream flux of carotenoid metabolism in grape berries showed regional differences. This study lays a foundation for future research to explore the molecular basis of climatic influences on carotenoid, norisoprenoid, and ABA biosynthesis.

•The SPME conditions of volatiles in dried fruits were optimized.•An appropriate substrate concentration was beneficial to the detection of volatiles.•Aromatic profiles of the raisins dried from the two green varieties were similar.•Floral aroma was the most remarkable characteristic in Zixiang Seedless raisins.The conditions of sample pretreatments and HS-SPME for extracting volatile compounds from raisins were optimized, and the method was validated in the study. Free and glycosidically bound volatile compounds in three different fragrance intensities raisins were analysed using this method. There were 91 compounds identified, and 72, 26 and 8 of these compounds came from fresh grapes, the auto-oxidation of unsaturated fatty acids (UFAO) and the Maillard reaction, respectively. The aroma profiles of Thompson Seedless raisins (TSRs) and Centennial Seedless raisins (CSRs) were similar, while the floral, fruity, green and roasted aromas of CSRs were higher than those of TSRs due to the contributions of benzeneacetaldehyde, 2-pentylfuran, (E)-2-nonenal and 3-ethyl-2,5-dimethyl pyrazine. Decanal, rose oxide, geraniol, linalool and β-damascenone made the floral and fruity aromas of Zixiang Seedless raisins (ZSRs) greater than those in TSRs and CSRs, but the green and roasted aroma intensities of ZSRs were lower.