Resistance Gene Composition Of Differential Cultivars For Rice Blast Pathosystem

As one of the important food crops,rice plays an important role in achieving global food security.Rice blast is a destructive disaster caused by Magnaporthe oryzae,a filamentous ascomycete fungus,which is the most serious threat to rice production.One of the most important ways to control the disease is to explore and utilize the resistant genes and cultivate the rice varieties with broad-spectrum and durable resistance.The differential cultivars are composed of a group of representative varieties with different disease resistant genotypes.It is a bridge between host plants and pathogens to comprehensively and accurately identify different physiological races(pathogenic types)in the pathogen population.In order to use the different differential cultivars more reasonably and interpret their identification results more accurately,the purpose of this study is to develop and use specific molecular markers of 29 cloned disease resistance genes to conduct comprehensive genotype identification of 4 sets of differential cultivars(i.e.Chinese differential cultivars,Japanese differential cultivars,IRRI near isogenic line differential cultivars and IRRI single gene line differential cultivars),so as to determine the composition of disease resistance genes.The main results obtained are as follows:1.Resistance gene Composition of Chinese differential cultivarsA total of 14 resistance genes including Pi37/Pish,Pib,Pi63,Pid-2,Pid-3,Pid-4,Pik,Pi1,Pia,Pi54,Pit,Pita and Ptr were detected in 7 Chinese differential cultivars.Among them,5 cultivars carried Pi63 gene,4 cultivars carried Pi37/Pish,Pid2,Pid3 and Pita gene respectively,and 3 cultivars carried Pib,Pid4,Pia and Pit genes respectively.The number of resistance genes in each cultivar was between 1-10.2.Resistance gene Composition of Japanese differential cultivarsA total of 17 resistance genes including Pi37/Pish,Pib,Pid-2,Pid-3,Pid-4,Piz-t,Pii,Pik,Pik-m,Pik-s,Pik-p,Pia,Pi54,Pit,Pita and Ptr were detected in 12 Japanese differential cultivars.Among them,8 varieties carried Pi37/Pish gene,7 varieties carried Pi54 gene,3 varieties carried Pik-s gene,and 2 varieties carried Pia and Pita gene respectively.The number of resistance genes of each variety was between 2 and 6.3.Resistance gene Composition of IRRI near isogenic line differential cultivarsA total of 11 disease resistance genes including Pib,Pi63,Pid-2,Pid-3,Pid-4,Pi2,Pi5,Pi1,Pia-C,Pit and Pita were detected in 7 IRRI near isogenic linedifferential cultivars.Among them,seven genes including Pib,Pi63,Pid-2,Pid-3,Pia-C,Pit and Pita were found in all varieties.Three varieties carried Pi1 gene,one variety carried Pi2 gene and one variety carried Pi5 gene.The number of resistance genes carried by each variety was between 8 and 9.4.Resistance gene Composition of IRRI single gene line differential cultivarsA total of 25 disease resistant genes including Pi37/Pish,Pi35,Pib,Pi63,Pid-2,Pid-3,Pid-4,Pi2,Pi9,Piz-t,Pii,Pi5,Pik,Pik-m,Pik-s,Pi1,Pik-h,Pik-p,Pik-l,Pia,Pia-C,Pi54,Pita and Ptr were detected in 37 IRRI single line differential cultivars.Among them,16 varieties may carry Pik-l contained in their common parent LTH,two varieties carry a single resistance gene,and the number of resistance genes carried by the other 35 varieties was between 2-10.