Dynamic changes in the endophytic bacterial communities of Huanglongbing-affected periwinkle leaves

Xiaofei Liu^*Yuli DaiLin GanChengzhong LanHongchun RuanLizhen ZhengYu ZhengYun GanXiujuan Yang^*

• Fujian Academy of Agricultural Sciences, Fuzhou, China

The pathogenetic mechanisms of citrus Huanglongbing (HLB) disease caused by Candidatus Liberibacter asiaticus (Clas) remain unclear, particularly how it is associated with host-related microbial communities. HLB infection has been demonstrated to alter endophytic bacteria that may be the cause of initiating disease. In this study, periwinkle plants were used as a model and inoculated with equal intensity by grafting infected citrus shoots with HLB. Leaf samples were collected at 30, 60, and 90 dpi to assess alterations in endophytic bacterial communities by high-throughput sequencing, uninfected periwinkle plants served as controls. Across all samples, 24 bacterial phyla and 300 genera were identified. In healthy plants, the endophytic bacterial diversity and richness remained relatively stable over time, with Arcobacter, Pseudomonas, and Giesbergeria identified as the predominant genera. In contrast, HLB-infected plants exhibited a marked decline in bacterial diversity over time, though richness was not significantly affected. Notably, the relative abundance of Candidatus Liberibacter increased significantly, becoming the dominant genus by 30 dpi, followed by Arcobacter and Pseudomonas. HLB infection was also associated with a sustained reduction in abundance of certain genera, including Anaerovorax, Neisseria, and Paeniclostridium. This work provides a detailed overview of the temporal dynamics of leaf endophytic bacterial communities following HLB infection of periwinkle. This study enhances our understanding of host-microbe-pathogen interactions and may guide future studies aiming to select useful microbial candidates for HLB alleviation and plant resilience.