White rot, caused by Coniella vitis, is a devastating disease in grapevine (Vitis vinifera) that seriously affects yield and quality. Breeding resistant grapevine varieties is a highly economical, environmentally friendly, and effective strategy to protect against the disease; however, this strategy requires a comprehensive understanding of the genes and pathways related to resistance. In this study, we sequenced the transcriptome of V. vinifera L. cv. GF, a highly resistant variety, at six time points after C. vitis inoculation. A transcriptome analysis showed that the salicylic acid (SA) signaling pathway was activated in response to C. vitis. Transient silencing of the VvTGA8 gene in the cv. GF greatly increased susceptibility to C. vitis. Subcellular localization studies showed that the VvTGA8 gene is localized in the nucleus. Heterologous expression of VvTGA8 in Solanum lycopersicum improved resistance to C. vitis and increased levels of the SA signaling pathway marker genes SlPR1 and SlPR2 significantly. To explore the mechanism by which VvTGA8 mediates disease resistance, we silenced SlICS1, a key gene in the SA synthesis pathway, through virus-induced gene silencing to inhibit SA synthesis in a VvTGA8 overexpression line, resulting in significantly weakened resistance to C. vitis and decreased expression levels of SlPR1 and SlPR2. We conclude that VvTGA8 is involved in SA signaling pathway, which activates the expression of pathogenesis-related genes in the nucleus, thereby mediating resistance to C. vitis in grapevine. This study provides an excellent target gene for disease-resistant breeding and gene editing in grapevine.

Downy mildew caused by Plasmopara viticola is an important disease in grape production, particularly in the highly susceptible, widely cultivated Vitis vinifera L. Breeding for disease resistance is an effective solution, and V. vinifera intraspecific crosses can yield progeny with both disease resistance and high quality. To assess the potential of intraspecific recurrent selection in V. vinifera (IRSV) in improving grapevine resistance to downy mildew and to analyze the pattern of disease resistance inheritance, the disease-resistant variety Ecolly was selected as one of the parents and crossed with Cabernet Sauvignon, Marselan, and Dunkelfelder, respectively, creating three reciprocal combinations, resulting in 1657 hybrid F1 progenies. The primary results are as follows: (1) significant differences in disease resistance among grape varieties and, significant differences in disease resistance between different vintages of the same variety were found; (2) the leaf downy mildew resistance levels of F1 progeny of different hybrid combinations conformed to a skewed normal distribution and showed some maternal dominance; (3) the degree of leaf bulbous elevation was negatively correlated with the level of leaf downy mildew resistance, and the correlation coefficient with the level of field resistance was higher; (4) five progenies with higher levels of both field and in vitro disease resistance were obtained. Intraspecific hybridization can improve the disease resistance of offspring through super-parent genetic effects, and Ecolly can be used as breeding material for recurrent hybridization to obtain highly resistant varieties.

Grapevine ( Vitis vinifera ) is a fruit that is widely cultivated worldwide, but white rot, caused by Coniella vitis , significantly impacts its yield and quality. The lack of resistance genes poses a major challenge to breeding grapevine varieties resistant to white rot. The LysM-containing receptor-like kinase (LYK) family genes are known to mediate immune responses to pathogens by recognizing pathogen-associated molecular patterns. To explore the resistance genes underlying white rot resistance, whole-transcriptome sequencing was carried out on grapevine cv. Guifeimeigui (GF, resistant phenotype) and cv. Red Globe (RG, susceptible phenotype) after challenge with C. vitis . Functional characterization and mechanistic analysis were conducted through virus-induced gene silencing (VIGS) in grapevine, stable overexpression in grapevine calli, and heterologous expression in tomato ( Solanum lycopersicum ). Differentially expressed genes (DEGs) enriched in the “Plant-pathogen interaction” pathway were identified, followed by expression clustering analysis to pinpoint 14 candidate genes. Silencing of VvLYK6 in GF resulted in a significant reduction in resistance to white rot, while its overexpression in grapevine calli inhibited the growth of C. vitis . VvLYK6 is localized to the cell membrane. SlLYK1 was involved in the resistance to C. vitis in tomato that was mediated by VvLYK6 . The overexpression of VvLYK6 in tomato also activated the salicylic acid signaling pathway and upregulated related pathogenesis-related genes, moreover induced a burst of reactive oxygen species, thereby increasing resistance to white rot. This study identifies VvLYK6 as a critical regulator of white rot resistance, and reveals its immune mechanism, and highlights its potential as a target for breeding and genetic improvement of durable resistance in grapevine.