Identification and Introgression of Bacterial Blight Resistance From African Rice (Oryza Glaberrima Steud.)

Abstract Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae ( Xoo ) is one of the major diseases affecting rice production. In the present study, 31 accessions of O. glaberrima were screened for BB resistance consecutively for four seasons and identified 28 stable BB resistant accessions with a mean lesion length of < 3cm. Molecular characterization revealed absence of xa 5, xa 13, Xa 21, Xa 38, xa 41(t) and xa 45, indicating the possibility of presence of novel gene(s) conferring BB resistance. In order to transfer BB resistance from O. glaberrima , resistant accession EC861812 was crossed to the susceptible cultivar, IR64 and BC 2 F 2 population developed. Genetic studies in BC 2 F 2 population showed transgressive segregation which indicates that O. glaberrima also harbor beneficial alleles for yield related traits. Six resistant BC 2 F 2 plants with mean lesion length of 0.1-0.8 cm were genotyped with 70 parental polymorphic SSR markers which revealed recurrent parent genome 65.1 to 84.5% with average of 67.5%. The BB resistant introgression lines identified in the present study will serve as pre-breeding lines for mapping of BB resistance derived from O. glaberrima .