Burkholderia spp. from HLB-Escape Rhizosphere Suppress Candidatus Liberibacter asiaticus Titers and Induce Defense Responses in Citrus

Citrus Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus (CLas), is the most devastating citrus disease, with no effective control strategies currently available. This study investigated the contribution of the rhizosphere microbiome to HLB resistance by comparing bacterial communities associated with symptomatic and escape trees. Escape trees harbored distinct microbial communities, with notable enrichment of Paraburkholderia spp. Among over 300 isolates, four Burkholderia strains (G23, G24, G25, and G29) exhibited strong inhibitory activity against CLas-related bacteria and close phylogenetic affiliation with Burkholderia theae XITOU. Genomic analyses revealed genes associated with environmental adaptation and host interaction. All four strains suppressed CLas proliferation and induced defense-related gene expression in citrus. Notably, strain G24 significantly reduced CLas titers, alleviated disease symptoms, and promoted plant recovery under field conditions, highlighting its potential as a microbial strategy for HLB management.