Genome‐Wide Association Study Reveals Insect Genetics and Microbial Symbiont Effects on Susceptibility of Diaphorina citri to the Citrus Greening Pathogen, Candidatus Liberibacter Asiaticus

Insect-vectored pathogens pose a significant threat to global agriculture. The colonization efficiency of pathogens in vectors plays a central role in these pathosystems, yet studies of the factors that affect this aspect are limited. This study investigates the genetic and microbial symbiont factors influencing the susceptibility of Diaphorina citri to Candidatus Liberibacter asiaticus (CLas), the pathogen causing citrus greening disease (huanglongbing). Through a microbiome Genome Wide Association Study (mGWAS) based on 16S amplicon sequencing and genomic resequencing of 120 D. citri individuals from six populations, we identified 79 SNPs significantly associated with the relative abundance of CLas within insects. Additionally, some of these SNPs were also associated with the relative abundance of Candidatus Profftella armature, a key endosymbiont of D. citri. SNPs in the regulatory region of gene Dcitr04g11610.1 led to its overexpression in CLas-susceptible D. citri, and CLas infection further elevated its expression. Conversely, RNAi knockdown of Dcitr04g11610.1 reduced CLas infection rates and abundance, accompanied by increased abundance of Profftella. Phylogenetic analysis revealed Dcitr04g11610.1's high homology to Major Facilitator Superfamily-type transporter SLC18B1 proteins, suggesting a role in CLas polyamine utilization. These findings highlight the importance and potential interplay of insect genetics and symbiotic microbiota in insect-vectored plant pathogen systems.