A prophage‐encoded effector from "Candidatus Liberibacter asiaticus" targets ASCORBATE PEROXIDASE6 in citrus to facilitate bacterial infection. (24th January 2023) - Du, Jiao
Abstract: Citrus huanglongbing (HLB), associated with the unculturable phloem‐limited bacterium " Candidatus Liberibacter asiaticus" ( C Las), is the most devastating disease in the citrus industry worldwide. However, the pathogenicity of C Las remains poorly understood. In this study, we show that AGH17488, a secreted protein encoded by the prophage region of the C Las genome, suppresses plant immunity via targeting the host ASCORBATE PEROXIDASE6 (APX6) protein in Nicotiana benthamiana and Citrus sinensis . The transient expression of AGH17488 reduced the chloroplast localization of APX6 and its enzyme activity, inhibited the accumulation of reactive oxygen species (H2 O2 and O2 − ) and the lipid oxidation endproduct malondialdehyde in plants, and promoted the proliferation of Pseudomonas syringae pv. tomato DC3000 and Xanthomonas citri subsp. citri . This study reveals a novel mechanism underlying how C Las uses a prophage‐encoded effector, AGH17488, to target a reactive oxygen species accumulation‐related gene, APX6, in the host to facilitate its infection. Abstract : " Candidatus Liberibacter asiaticus" effector AGH17488 manipulated host reactive oxygen species levels through targeting the APX6‐dependent pathway, thereby inhibiting plant immunity and facilitating pathogen infection.