Identification And Functional Analysis Of Unique Secreted Protein Genes In Fujian Isolate FJ81278ZB15 Of Magnaporthe Oryzae

Rice blast,caused by Magnaporthe oryzae which is considered as the first important fungal phytopathogen in the world,is the main diseases of rice,leading to significant yield and economic lossesand threatening global food security.Over the past few years,to prevent and control rice blast,researchers have devoted to cultivating a variety of disease resistant rice cultivars,however,due to the high genetic variation frequency of M.oryzae,new cultivars often lose their resistance within 3-5 years.Thus,cloning of new avirulence genes of rice blast fungus can promote our understanding of the mutation patterns of avirulence gene,as well as their interaction mechanism with resistance gene,which will be of great significance for clarifying the interaction mechanism between rice and Magnaporthe oryzae and ultimately cultivating the persistently resistant cultivars against rice balst.Referencing previous successful experiences,we attempted to combine whole genome resequencing with comparative genomics to clone new avirulence genes.Above all,we obtained 24 unique genes encoding predicted secreted proteins by comparing the FJ81278ZB15 genome with 70-15 genome.We therewith searched for the association between the DNA polymorphisms of these genes and virulences to certain resistace cultivars in 19 filed isolates.However,no any association was identified,and no any novel avirulence gene was obtained after the functional complementation experiments for all these unique genes either.Then,resequencing was conducted to get the better assembled genomes of FJ81278ZB15 and GUY 11 between which a wider range of virulence differences has been identified.18 unique genes encoding predicted secreted proteins were obtainedthrough comparative genomics.Association analysis revealed that 81278-12029 and 81278₁2373 had a high correlation with Avr-Pil and Avr-Pi4a,respectively.Moreover,functional complementation experiments also got 6 unique genes whose transformants could cause HR after inoculation,however,as those genes showed no association between DNA polymorphism and virulece to corresponding resistance cultivars,further assays were still needed to be conducted to confirm their biological fucntions.Lastly,13 Taiwan isolates and 7 Fujian isolates were also resequenced,and the DNA polymorphism assays indicated that most unique genes were under the host selection pressures.