Abstract:
Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is becoming a potential threat to rice crop in many regions of the world. In order to identify resistant sources to virulent isolates of bacterial blight, an experiment comprising 14 species of wild rice (Oryza sp.) and three widely used cultivated varieties of rice in Pakistan was conducted in the greenhouse of National Agricultural Research Centre, Islamabad during 2005. Adult plants were inoculated with virulent isolates of Xanthomonas oryzae pv. oryzae prevailing in NWFP, Pakistan i.e., Xo-103, Xo-107, Xo-139, Xo-143, Xo-304, Xo-351 and MNR-4. Of all the wild relatives of rice, O. nivara, O. longistaminata and O. grandiglumis showed resistance to all isolates. O. nivara even didn’t show any lesion against any isolate. Remaining wild species showed differential response to the isolates used in the study. These species were resistant to one or few isolates but expressed susceptibility to others. Bas-385, IR-6 and KSK-282, the cultivated varieties of Pakistan used in study were found susceptible to most of the isolates. The use of resistant wild species O. nivara, O. longistaminata and O. grandiglumis is, therefore, recommended in rice breeding programs for transfer of bacterial blight resistant genes to cultivated varieties.
