Functional Analysis Of Three Proteins With S TKC Domain In Magnaporthe Oryzae

In eukaryotic cells,a number of serine/threonine protein kinases play an important role in cytoskeleton,membrane organization,intracellular signalling and vesicular trafficking,most of which are well characterized in the Schizosaccharomyces pombe.However,except the yeast,the filamentous fungi contain a Kinl protein kinase that can regulate various cellular processes well-conserved in fungal pathogens.The deletion mutants of MoKinl displayed reduced mycelial growth,conidia formation and pathogenicity in Magnaporthe oryzae.To better investigate the functions of MoKinl,we predicted one of the ScKinl-interacing proteins ScCbkl by bioinformatic analysis.Further BLAST in the Magnaporthe genome database,we indentified four higher homologous proteins（MGG₀9519,MGG₀5376,MGG₀4475 and MGG₀2757）with high homology to the protein kinase ScCbkl.Further bioinformatics analysis showed that these genes shared a S TKC domain,function the kinase catalytic activity.We knocked out the three genes containing S_TKC domain and then analysed the phenotypes of these gene deletion mutants.We found that the deletion mutants of MGG 09519 exhibited slightly lower growth rate and pathogenicity to rice and barely comparing to wildtype and ectopic strains;there is no difference in conidial germination and appressorium formation.Besides,we found that the deletion mutants of MGG 04475 didn’t affect the growth rate,conidiation and pathogenicity to host.Finally,we found that the deletion of MGG 02757 gene led to reduced growth rate,conidiation and pathogenicity.In addition,the mitosis and translocation of the nucleus appear disordered in the deletion mutants of MGG 02757.Whereas we could not knock out MGG 05376,possibly because the loss of it will lead to the death of organisms.The results suggest MGG 09519 and MGG₀2757 among the 4 S_TKC domain proteins coding genes play an important role in the vegetative development and pathogenicity of Magnaporthe oryzae.Moreover,MGG₀2757 can also regulate conidiation,septum formation,appressorium formation and the mitosis of the nucleus,and so on.We will further study the mechanism of its regulation.