枣疯病枣树内生细菌多样性分析及生防菌筛选鉴定OA

Jujube witches broom disease,caused by phytoplasma,is a destructive plant disease affect-ing jujube trees.Studying the diversity of endophytic bacteria in infected trees and screening for po-tential biocontrol strains can provide insights into phytoplasma infection mechanisms and support the development of biological control strategies.In this study,roots and branches of both healthy and phytoplasma-infected jujube trees were analyzed using high-throughput sequencing to assess endophyt-ic bacterial diversity.Traditional isolation methods were combined with GFP fluorescence labeling to screen and validate potential biocontrol strains.The results showed that:(1)Compared with healthy trees,phytoplasma-infected jujube trees exhibited increased endophytic bacterial diversity in bran-ches,along with a higher relative abundance of Bacillus spp.In contrast,root endophytic bacterial diversity decreased,with a reduced relative abundance of Pseudomonas spp.(2)Fifteen endophytic bacterial strains were isolated from the roots of healthy trees.Among them,Pseudomonas sp.L2 stably colonized tissue-cultured jujube seedlings.When applied to phytoplasma-infected seedlings,strain L2 significantly increased plant height,fresh mass,and dry mass.In conclusion,phytoplasma infection reduces the diversity of endophytic bacteria in jujube roots,particularly diminishing the abundance of Pseudomonas spp.Moreover,the endophytic strain Pseudomonas sp.L2 alleviates dis-ease symptoms and shows potential as a biocontrol agent against jujube witches' broom disease.These findings lay the foundation for developing L2-based biocontrol formulations and advancing dis-ease management strategies.