The Rice Blast Resistance Gene Pid Family Has Been Strictly Diverged Into Indica And Japonica Subspecies

Abstract

Background: Rice blast (causative agent the fungus Pyricularia oryzae) represents a major constraint over the productivity of one of the world’s most important staple foods. Genes encoding resistance have been identified in both the indica and japonica subspecies genepools and combining these within new cultivars represents a rational means of combating the pathogen.Results: In this research, a deeper allele mining was carried out on Pid-2, Pid-3, and Pid-4 by each of comprehensive FNP marker set in the three panels consisting of 70 indica and 58 japonica cultivars. Within Pid-2, three functional and one non-functional alleles were identified; the former were only identified in indica type entries. At Pid-3, four functional and one non-functional alleles were identified, and once again, all of the formers were present in indica type entries. However, the pattern of variation at Pid-4 was rather different: here, the five functional alleles uncovered were dispersed across the japonica type germplasm. Among all the 12 candidate functional alleles, both Pid2-ZS and Pid3-ZS were predominant. Furthermore, the resistance functions of both Pid2-ZS and Pid3-ZS were assured by transformation test. Conclusions: Profiting from merits of three comprehensive FNP marker sets, the study has validated that all three members of the Pid family have been strictly diverged into indica and japonica subspecies: Pid-2 and Pid-3 were defined as indica type resistance genes, and Pid-4 as japonica one. Rather limited genotypes of the Pid family have been effective in both indica and japonica rice groups, of which Pid2-ZS+Pid3-ZS has been central to the Chinese rice population.