Molecular signatures between citrus and Candidatus Liberibacter asiaticus

Citrus Huanglongbing ( HLB), also known as citrus greening, is one of the most devastating citrus diseases worldwide. Candidatus Liberibacter asiaticus ( C Las) is the most prevalent strain associated with HLB, which is yet to be cultured in vitro. None of the commercial citrus cultivars are resistant to HLB. The pathosystem of Ca . Liberibacter is complex and remains a mystery. In this review, we focus on the recent progress in genomic research on the pathogen, the interaction of host and C Las, and the influence of C Las infection on the transcripts, proteins, and metabolism of the host. We have also focused on the identification of candidate genes for C Las pathogenicity or the improvements of HLB tolerance in citrus. In the end, we propose potentially promising areas for mechanistic studies of C Las pathogenicity, defense regulators, and genetic improvement for HLB tolerance/resistance in the future.