Analysis of Leaf Endophytic Bacterial Communities in Grape Varieties with Different Levels of Downy Mildew Resistance

To investigate the association between differences in resistance to grape downy mildew and endophytic bacterial communities in leaves, 16S rDNA high-throughput sequencing technology was employed to compare the diversity, composition, and structural differences of endophytic bacterial communities in healthy leaves of 6 grape varieties. The results showed significant differences in species richness and community structure among the 6 varieties. Among them, the number of unique OTUs, species richness, and community diversity of the disease-resistant variety 'Shine Muscat' were significantly higher than those of the susceptible variety 'Sweet Sapphire'. Disease-resistant varieties enriched potential disease resistance-related genera such as Sphingomonas, Flavobacterium, Pantoea, and Bacillus. LEfSe analysis indicated that differential species were specifically enriched in two disease-resistant varieties. Among them, o__Enterobacterales, f__Halomonadaceae, Candidatus Portiera, and o__Oceanospirillales were significantly enriched in 'Shine Muscat'; while fewer specifically enriched species were detected in 'Black Emperor', with only o__Rickettsiales identified. This study suggests that the enrichment characteristics of specific genera in the endophytic bacterial community of grape leaves are closely related to downy mildew resistance, and different disease-resistant varieties may enhance resistance through specific microbial communities.