Studies On The Biological Roles Of Type ? Myosin Light Chain MoRlc1 In Magnaporthe Oryzae

Rice blast,caused by Magnaporthe oryzae,is one of the most devastating diseases in rice planting,and could result in the global rice yield reduction by 10-30%every year.M.oryzae,a member of ascomycetes fungus,is a plant pathogenic fungus with whole genomic sequence being determined.,this fungus possesses of a typical life and infection cycle,and is considered to be an ideal model to study the gene function and pathogenic mechanism of filamentous fungi.In Schizosaccharomyces pombe,myosin II?Myo2?plays an important role in cytokinesis,and Rlc1 has been proved to be the regulatory light chain of myosin II protein.In our previous studies,we found that myosin II?Mo Myo2?is an important regulatory factor for the growth,development and pathogenicity of M.oryzae,however,the roles of its regulatory light chain Mo Rlc1 remains unclear.In this study,the biological roles of Mo Rlc1 in the growth,development and pathogenicity of M.oryzae was characterized,and the results are as following:The Morlc1 gene encoding the regulatory light chain of myosin II was cloned from M.oryzae and analyzed.Homologous recombination method was used to delete the Morlc1?MGG?12886?gene and two Morlc1 gene deletion mutants were finally obtained.Phenotypic test showed that the deletion of Morlc1 resulted in the retarded mycelial growth of M.oryzae,suggesting that Morlc1 might be involved in regulating the vegetative growth of M.oryzae;the sporulation stems in mutants significantly decreased compared with wild-type strain Guy11,which,as a result,led to reduced sporulation,suggesting that Morlc1 affected the formation of conidia of M.oryzae;the spore germination in Morlc1mutants was delayed,and the formation of appressorium was also delayed at 8 h,however,it could return to the same level of wild-type strains Guy11 at 12 h,suggesting that the deletion of Morlc1 did not affect the conidial germination and appressorium maturation of M.oryzae;the inhibition rate of mutants in the medium containing CFW?calcofluor white?or CR?calcofluor white?was significantly increased by the mutant in comparison to that of wild-type strain Guy11,however,when incubated in the medium containing H₂O₂,Na Cl,SDS and Sorbitol,the inhibition rate of the mutants was comparable to the wild-type strain Guy11,indicating that the Morlc1 mutant was only sensitive to the cell wall inhibitor,and and deetion of Morlc1 might result in the alteration of cell wall structure;futhermore,turgor pressure,rice pathogenicity,and barley infection of the mutants were also tested,and the results showed that the phenotypes of these mutants were similar to those of wild-type strain Guy11,indicating that Morlc1 deletion did not affect the appressorium function,and thus this gene was not involved in the infection and pathogenicity of M.oryzae.To sum up,we cloned the Morlc1 gene in this study,and targeted gene deletion was carried out to obtain the Morlc1 mutant.By comparing the biological functions of Morlc1mutants with the wild type Guy11,we found that Morlc1 is required for the regulation of vegetative growth,asexual spore formation and integrity of cell wall structure of M.oryzae,which also laid a foundation for further revealing its biological functions in M.oryzae.