A truncated TAL PthA efector of Xanthomonas citri subsp. citri is associated with canker resistance in Citrus limon

ROESCHLIN R; FAVARO M.A; CHIESA M.A; MARTIN, A.P.; ALEMANO, S; VOJNOV, A.A; CASTAGNARO, A; GADEA, J; MARANO, M.R

Foz Iguazu

Congreso; 11th Congreso Internacional de Biología Molecular de Plantas (IPMB 2015); 2015

Asiatic citrus canker is an important disease that affects many citrus species, and causes severe economic impact on the citrus-producing industry. Xanthomonas citri subsp. citri (X. citri), the causal agent of this disease, harbors four pthA genes encoding type III-secreted transcriptional activator-like (TAL) effectors, one of which (PthA4) is required for canker symptoms. The presence of pthA genes homologous may allow intergenic recombinations, driving the evolution and emergence of X. citri pathogenicity. Recently, we have identified a new variant of X. citri, named X. citri AT, which induces an atypical non-cankerous chlorotic phenotype in C. limon and weak cankerous lesions in C. clementina leaves. Characterization of this host-specific response shown that X. citri AT triggers subcellular changes associated with vacuolar cell death and an extensive reprogramming of defense-related genes in C. limon. Moreover, this defense response triggers protection to pathogenic X. citri strains. In this work, we have demonstrated that a truncated version of PthA from X. citri AT (PthAAT) is involved in this specific-defense response, leading to cell death in C. limon and other plant species. These findings highlight the importance to use TAL effector PthAAT to modulate the resistance to X. citri in Citrus spp.