Pathogenic Functions of MoDock1 and MoElmo1 in Magnaporthe oryzae

Objective Roles of the genes associated with MoDock1 and MoElmo1 proteins in Magnaporthe oryzae played in rice blast disease were studied.

Methods  Homologies of Dock180 and ELMO in M. oryzae were identified by bioinformatics method, and the coding genes knocked out to create mutants for determinations of phenotype and interactions between the two proteins by a co-immunoprecipitation test.

Results  MoDOCK1 and MoELMO1 were identified in M. oryzae and deleted to obtain the mutants that were almost identical in phenotype. Absence of the two proteins in the mutants significantly affected the conidial adhesion resulting in long bud tubes with septum and delayed the appressoria formation. Since the defective appressoria formation could be repaired by the addition of 8-Br-cAMP or IBMX, it suggested that MoDock1 and MoElmo1 might be involved in the cAMP-PKA signaling pathway. To test that hypothesis, onion epidermis was infected with the mutants to show a declined infectious ability, and on a rice plant, a lowered pathogenicity. Furthermore, the co-immunoprecipitation experiment confirmed the MoDock1-MoElmo1 interaction as well.

Conclusion MoDock1 and MoElmo1 in M. oryzae provided the conidia adhesion and appressoria formation essential for the pathogenicity of the pathogen on rice.