Identification of a Recessive Resistance Gene in Induced Mutant Line XM5 of Rice to Rice Bacterial Blight

Abstract

In an earlier study (TAURA et al. 1991), XM5, a mutant line of rice induced by Nmethyl-N-nitrosourea, was confiruled to carry a single recessive gene resistant to all known Philippine races of bacterial blight (BB) caused by Xanthomonas campestris pv. oryzae. To clarify the allelic relationships between the resistance gene of XM5 and the three known recessive genes, xa-5, xa-8, and xa-13, F₁ plants and F₂ populations from the crosses between XM5 and rice cultivars carrying the known recessive genes were analyzed with Philippine BB races. Results showed that the recessive resistance gene of XM5 is not allelic with the three known recessive genes, xa-5, xa-8, and xa-13. Thus we concluded that the resistance gene of XM5 is a new one, and designated it as xa-19, following the rule of gene symbolization of the Rice Genetics Cooperative.