Abstract:

Magnaporthe oryzae is a fungal pathogen causing blast disease in different stages of rice. In eukaryotes, the highly conserved protein kinase CK2 contains two regulatory subunits and two catalytic subunits. MoCK2, CK2 homologus in M. oryzae, is encoding by three genes, MoCKb1 and MoCKb2 encode two different regulatory subunits, and MoCKa encodes its catalytic subunit. MoPpz1, one of serine/threonine phosphatase obtained by pull-down assay of MoCKa-GFP in M. oryzae, was researched at its function by reverse genetic approache and homologous recombination principle in our study. It was found that Ppz1 had different functions in various fungi by bioinformatics analysis, and showed that Ppz1 and it’s homolog proteins in other model fungi had highly identity in the protein sequences. ΔMoppz1 mutant obtained by gene knock-out and genotyping screen, while the mutant was not affected in vegetative growth and conidial production, the mutant showed development delay of conidium from germination to appressorium and reduced pathogenicity to rice after phenotypic assay comparing with wildtype strain Ku80. Confocal laser scanning microscopy analysis showed that MoPpz1 was localized in the cytoplasm of hyphae, conidium and appressorium. In conclusion, the protein phosphatase MoPpz1 may be involved in the regulation of conidial germination, appressorial formation in M. oryzae and pathogenicity to rice.

Key words: Magnaporthe oryzae, gene knockout, ΔMoppz1, functional analysis