Genetic Analysis of Myanmer Rice Cultivars for Resistance to Bacterial Blight.

Abstract

Rice cultivars from Myanmar were classified into five groups based on their reaction pattern to bacterial blight (BB) Xanthomonas campestris X. oryzae pv. oryzae races. A random sample of cultivars from each group was genetically analysed to verify their grouping. The selected cultivars were crossed with IR24 which is susceptible to all Philippine races of BB. The F1 and F2 populations were inoculated by the clipping method. Segregation data revealed that single dominant genes conferred resistance in cultivars belonging to CAS209, TKM6 and Java14 groups and a single recessive gene conveyed resistance in cultivars belonging to DZ192 group. The cultivars belonging to Mond Ba group had two dominant genes for resistance. Allelic relationships of genes of cultivars belonging to different groups were tested by inoculating F1 and F2 populations from crosses of these cultivars with the respective tester of each group. The results revealed that all the cultivars belonging to Java 14, TKM6, DZ192 and CAS209 groups had Xa-3, Xa-4, xa-5 and Xa-10 genes for resistance and cultivars belonging to Mond Ba group had both Xa-4 and Xa-10 for resistance. The results confirmed that cultivars with Xa-10 and Xa-4 predominated amongst BB resistant cultivars from Myanmar and the frequency of cultivars with Xa-3 and xa-5 was low.