RESISTANCE TO RICE TUNGRO VIRUSES IN WILD-SPECIES OF RICE (ORYZA SPP)

Wild species of rice (Oryza spp.) and African cultivated rice, O. glab errima STEUD, were evaluated as possible sources of resistance to rice tungro disease. Two hundred and seven accessions, representing the ge netic diversity in the genus Oryza, were tested for resistance to rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV ) infection. Of these, 49 and 15 accessions were not infected with RTS V and RTBV, respectively, when plants were inoculated with viruliferou s green leafhopper. Three accessions of O. rufipogon GRIFF. (Internati onal Rice Germplasm Center Acc. no. 105908, 105909 and 105910) did not show infection with either RTSV or RTBV. In addition, two accessions of O. officinalis WALL ex WATT (IRGC 105100 and 105365) and one each o f O. rhizomatis VAUGHAN (IRGC 103421) and O. brachyantha A.HEV. (IRGC 100115) were not infected with either tungro viruses. Although a large number of cultivated rice have been evaluated for resistance to tungr o, cultivars resistant to RTBV have not been found. The wild species i dentified as highly resistant to tungro are useful donors in developin g tungro-resistant rice germplasm.