The impact of ampicillin on the structure and function rhizosphere microbiota in Huanglongbing-affected citrus

To investigate the impact of AMP on the rhizosphere bacterial community in citrus infected with Huanglongbing (HLB), diseased Citrus (Citrus reticulata Blanco cv. Shatangju) were treated with regular ampicillin injections and monitored CLas (Candidatus Liberibacter asiaticus) dynamic changes. The alterations in the rhizosphere bacterial community were analyzed using 16S rDNA amplicon sequencing.The results demonstrated that HLB infection increased the richness of rhizosphere bacteria, whereas AMP treatment significantly reduced bacterial diversity, lowering it below the level observed in healthy plants. AMP notably enriched bacterial genera with antimicrobial potential and the ability to activate plant immunity (e.g., Burkholderia-Caballeronia-Paraburkholderia), while decreasing the abundance of potential pathogens, HLB-associated bacteria, and denitrifying bacteria. However, AMP also disrupted the balance of certain bacteria and induced the enrichment of organic pollutant-degrading bacteria, suggesting that plants may perceive AMP as a stressor.This study reveals that ampicillin enhances plant disease resistance by reshaping the microbial community, yet its application may pose potential ecological risks, necessitating careful evaluation before practical implementation.