Citrus genomic resources unravel putative genetic determinants of Huanglongbing pathogenicity

Citrus HLB caused by Candidatus Liberibacter asiaticus is a pathogen-triggered

immune disease. Here, we identified putative genetic determinants of HLB

pathogenicity by integrating citrus genomic resources to characterize the pan

genome of accessions that differ in their response to HLB. Genome-wide associ

ation mapping and analysis of allele-specific expression between susceptible,

tolerant, and resistant accessions further refined candidates underlying the

response to HLB. We first developed a phased diploid assembly of Citrus sinensis

‘Newhall’ genome and produced resequencing data for 91 citrus accessions that

differ in their response to HLB. These data were combined with previous rese

quencing data from 356 accessions for genome-wide association mapping of

the HLB response. Genes determinants for HLB pathogenicity were associated

with host immune response, ROS production, and antioxidants. Overall, this

study has provided a significant resource of citrus genomic data and identified

candidate genes to be further explored to understand the genetic determinants

of HLB pathogenicity