Genetics of bacterial blight resistance in a breeding line of rice

The genetics of resistance in rice breeding line IR1545-339 to strains of four races of Xanthomonas campestris pv. oryzae in the Philippines was studied. The analysis of F<SUB>1</SUB> and F<SUB>2</SUB> populations from the cross of IR 1545-339 with susceptible cultivar TN1 demonstrated that recessive gene xa-5 conferred the high resistance of IR1545-339 to races 1, 2, and 3. The moderate resistance of IR1545-339 to a strain of race 4, which is characterized by slow lesion development, also appeared to be governed by xa-5. Trisomic analysis revealed that xa-5 is located on chromosome 2 as designated by Nishimura