The color of berry skin is an important economic trait for grape and is essentially determined by the components and content of anthocyanins. The fruit color of Chinese wild grapes is generally black, and the profile of anthocyanins in Chinese wild grapes is significantly different from that of Vitis vinifera. However, V. davidii is the only species that possesses white berry varieties among Chinese wild grape species. Thus, we performed a transcriptomic analysis to compare the difference of transcriptional level in black and white V. davidii, in order to find some key genes that are related to anthocyanins accumulation in V. davidii. The results of anthocyanins detection revealed that 3,5-O-diglucoside anthocyanins is the predominant anthocyanins in V. davidii. It showed obvious differences from V. vinifera in the profile of the composition of anthocyanins. The transcriptome sequencing by Illumina mRNA-Seq technology generated an average of 57 million 100-base pair clean reads from each sample. Differential gene expression analysis revealed thousands of differential expression genes (DEGs) in the pairwise comparison of different fruit developmental stages between and within black and white V. davidii. After the analysis of functional category enrichment and differential expression patterns of DEGs, 46 genes were selected as the candidate genes. Some genes have been reported as being related to anthocyanins accumulation, and some genes were newly found in our study as probably being related to anthocyanins accumulation. We inferred that 3AT (VIT_03s0017g00870) played an important role in anthocyanin acylation, GST4 (VIT_04s0079g00690) and AM2 (VIT_16s0050g00910) played important roles in anthocyanins transport in V. davidii. The expression of some selected DEGs was further confirmed by quantitative real-time PCR (qRT-PCR). The present study investigated the transcriptomic profiles of berry skin from black and white spine grapes at three fruit developmental stages by Illumina mRNA-Seq technology. It revealed the variety specificity of anthocyanins accumulation in V. davidi at the transcriptional level. The data reported here will provide a valuable resource for understanding anthocyanins accumulation in grapes, especially in V. davidii.

Berry firmness is one of the most important quality traits in table grapes. The underlying molecular and genetic mechanisms for berry firmness remain unclear. We constructed a high-density genetic map based on whole-genome resequencing to identify loci associated with berry firmness. The genetic map had 19 linkage groups, including 1662 bin markers (26,039 SNPs), covering 1463.38 cM, and the average inter-marker distance was 0.88 cM. An analysis of berry firmness in the F1 population and both parents for three consecutive years revealed continuous variability in F1, with a distribution close to the normal distribution. Based on the genetic map and phenotypic data, three potentially significant quantitative trait loci (QTLs) related to berry firmness were identified by composite interval mapping. The contribution rate of each QTL ranged from 21.5% to 28.6%. We identified four candidate genes associated with grape firmness, which are related to endoglucanase, abscisic acid (ABA), and transcription factors. A qRT-PCR analysis revealed that the expression of abscisic-aldehyde oxidase-like gene (VIT_18s0041g02410) and endoglucanase 3 gene (VIT_18s0089g00210) in Muscat Hamburg was higher than in Crimson Seedless at the veraison stage, which was consistent with that of parent berry firmness. These results confirmed that VIT_18s0041g02410 and VIT_18s0089g00210 are candidate genes associated with berry firmness.

Methyl jasmonate (MeJA) plays a vital role in plant disease resistance and also induces the expression of disease resistance genes in plants. In this study, a transcriptome analysis was performed on grapevine leaves after 12, 24 and 48 h of MeJA-100 μM treatment. A total of 1242 differentially expressed genes (DEGs) were identified from the transcriptome data, and the analysis of the DEGs showed that genes related to phytohormone signal transduction, jasmonic acid-mediated defense, Mitogen-activated protein kinase (MAPK), and flavonoid biosynthetic pathways were upregulated. As Pathogenesis-related gene 1 (PR1) is an important marker gene in plant defense also upregulated by MeJA treatment in RNA-seq data, the VvPR1 gene was selected for a promoter analysis with β-glucuronidase (GUS) through transient expression in tobacco leaves against abiotic stress. The results showed that the region from −1837 bp to −558 bp of the VvPR1 promoter is the key region in response to hormone and wound stress. In this study, we extended the available knowledge about induced defense by MeJA in a grapevine species that is susceptible to different diseases and identified the molecular mechanisms by which this defense might be mediated.

Global climate warming will significantly impact grapevine growth and development, and thus grape and wine industries worldwide. Heat-tolerant germplasms are very valuable for grapevine breeding programs. In this study, we assessed the thermotolerance of 247 wild grape accessions by chlorophyll fluorescence parameter (F_v/F_m) under critical high temperature according to Xu et al. in 2016, 2017, and 2018. The results showed that 36 grape accessions showed strong heat tolerance. Therefore, these accessions can be used as parents for breeding heat-tolerant grape cultivars.