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

Abstract

Line XM5, which has a single gene conferring resistance to all Philippine races of bacterial blight (BB; caused by Xanthomonas campestris pv. oryzae), was derived from the susceptible line IR24 treated with N-methyl-N-nitrosourea. XM5 was crossed with resistant lines IR-BB5, IR-BB8 and BJ1 (carrying the genes xa-5, xa-8 and xa-5 plus xa-13, respectively). F1 and F2 populations were artificially inoculated with 6 races of BB and evaluated for disease resistance. Results showed that the recessive gene of XM5 was not allelic with the 3 known recessive genes and was therefore designated xa-19.