Identification of new sources of bacterial blight (Xanthomonas oryzae pv. oryzae) resistance in wild Oryza species and O. glaberrima

Abstract

Bacterial blight (BB) of rice is a widespread disease in tropical Asia, contained largely through the deployment of race-specific resistance genes. Although more than 25 BB resistance genes have been identified, none are effective individually against all the pathotypes prevalent in north-western India. The response of a set of 327 accessions of 13 wildOryzaspecies and cultivated African rice,O.glaberrima, was evaluated to infection with seven pathotypes ofXanthomonas oryzaepv.oryzaeover a period of 3–4 years. Of these, 67 were resistant or moderately resistant to all pathotypes. These comprised 13 accessions ofO.glaberrima, 5 ofO. barthii, 10 ofO.rufipogon, 4 ofO.longistaminata, 22 ofO.nivara, 6 ofO.officinalis, 2 ofO.rhizomatisand 5 ofO.minuta. Inheritance studies, molecular mapping and transfer of some of these genes intoO.sativassp.indicaare in progress.