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Downy mildew is a fungal disease that seriously threatens the normal growth and fruit quality of grapes; therefore, it is urgent to identify resistant germplasm resources. To identify the differences in the resistance rates of various Chinese wild grapevine plants to downy mildew, 120 grapevine germplasm resources were selected as experimental materials. Leaf disk in vitro testing was applied to evaluate the downy mildew resistance level of plants, and quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to test the expression patterns of some key genes at different time courses after inoculation with Plasmopara viticola. Additionally, simple sequence repeat (SSR) markers were selected to identify resistance in different grapevine cultivars and to provide a basis for marker-assisted selection. The results showed that the disease index of 120 grapevine germplasm resources ranged from 0 to 78.70. Among the 120 grapevine varieties, 5 Vitis rotundifolia presented immunity to downy mildew; 3 wild grapevine strains, including Yunnan-Yuanmou 2, Yunnan-2, and Muzhaling-3, were highly resistant strains; 38 grapevine strains were resistant varieties, 71 grapevine strains were susceptible varieties, and 3 V. vinifera strains, namely Italian Riesling, Medoc Noir, and Gamay Teinturier were highly susceptible to downy mildew. After infection with P. viticola, the expression patterns of key genes in resistant and susceptible plants were different. Except for WRKY33, which showed a low expression level in all plants, all the genes presented an initial increasing trend followed by a decreasing trend over the inoculation period. Among the 30 pairs of SSR markers, 22 SSR markers, including CHr14V015, UDV-370 and GF09-46, could explain only 25.83–48.33% of the phenotypic variation, which means that they cannot be applied for downy mildew resistance identification. The RGA9 marker explained the highest phenotypic variation, at 80.83%, and was expected to be a standard marker that can be applied in disease-resistance production, thus providing the basis for both the rapid and mass identification of downy mildew resistance in grapevine germplasm resources and marker-assisted selection.

Chinese wild grapevine is an important germplasm source worldwide; thus, it is necessary to study its genetic diversity, population structure, and linkage disequilibrium (LD). In this study, 81 strains of Chinese wild grapevine were studied and constituted the core collection. These strains were genotyped according to 160 genome-wide SSR (simple sequence repeat) markers. All SSR markers were widely spread across the strains and revealed a total of 3469 alleles. After population structure analysis, all the Chinese wild grapevine strains were grouped into two subgroups that were well matched with the geographical distribution and the results published by our research team. Of all SSR pairs, 8.3% (P 2 value was 0.0229. The LD decay distance across Chinese wild grapevine was up to 14.13 cM, below the critical r 2 value of 0.1, following y = −0.0383 ln (x) + 0.2016. According to both the linear mixed model and general linear model, the associations of the 160 SSR markers with grape white rot resistance were calculated. Five associated markers were located, four of which had been previously associated with other resistance traits and one of which was new. Chinese wild grapevine association mapping was performed to anchor useful quantitative trait loci (QTLs), and the five markers identified can help us anchor additional resistance-associated genes.

Grapevine (Vitis spp.) is an important crop worldwide, but its growth, fruit quality, and yield are frequently reduced by pathogens. Admixture of resistance genes is an effective method to breed new varieties. Wild grapevine populations are very important subjects for grapevine research, given their germplasmic resistance to various diseases, especially white rot disease caused by Coniella diplodiella. However, molecular and sequencing research is still required to fully understand the relationships among Vitis spp., particularly among Chinese Vitis species. We analyzed 88,877 single nucleotide polymorphisms (SNPs) from 386 grapevine genotypes through restriction site-associated DNA sequencing. Overall, Chinese Vitis spp. had considerably less linkage disequilibrium and exhibited stronger resistance to white rot disease than their European congeners. Association analysis revealed six SNPs associated with eight candidate genes linked to white rot resistance that were up-regulated by the pathogen. In resistant Vitis spp., genes XM_002272404.2 (WAT1-related protein At3g30340-like), XM_002278827.2 (receptor-like protein kinase HSL1), XM_002281911.3 (ethylene-responsive transcription factor ERF105-like), XM_002281568.4 (leucine rich repeat receptor-like serine/threonine-protein kinase At1g74360-like), and XM_003634259.2 (zinc finger RNA-binding protein) were more up-regulated by the pathogen than in susceptible Vitis species. The present results clarify the genetic basis of the geographical distribution, classification, and resistance traits of Chinese Vitis spp., thereby contributing to the use of wild Chinese Vitis spp. in breeding.

China is one of the major diversity centres of grape (Vitis spp.) and is therefore one of the most abundant sources of Vitis germplasm in the world. Grape wild relative species (GWRs) represent a potentially important source of valuable traits for the improvement of cultivated grape varieties and have significant characters for resistance to biotic and abiotic stress factors. We studied the ecogeographic diversity of GWRs, conservation gaps and impact of climate change on GWRs in China, based on a wide range of distribution data sourced from germplasm and herbarium specimens, field surveys and other literature. Results show that there are 39 species, 1 subspecies and 14 varieties of GWRs native to China and that 19 species and 9 varieties are the closest wild relatives to cultivated grape according to the Taxon Group Concept. GWRs are distributed in nearly all provinces in China except for Xinjiang, but they are particularly abundant in Jiangxi and Hunan provinces. The richest regions for GWRs are the Qinling, Daba, Wuling, Nanling and Wuyi mountains. Around 22% of GWR species are found in natural reserves (NRs) and are well protected, but 15 species are not found in NRs and require further strengthening of both protection and collection. The potential distribution of GWRs at the present and predicted future climate was compared using BIOCLIM. The results showed that simulated current distributions matched actual distribution ranges. Under the future climate scenario with doubled CO2 concentration, suitable areas for continued survival of 21 GWRs could be reduced. Our results will therefore be extremely valuable for the development of a complementary conservation strategy for Vitis in China.