Phenotypic and Molecular Characterization of Tungro Resistant Introgression Lines Derived from the Cross Oryza sativa L. x Oryza rufipogon GRIFF
Bandillo, N.B.; Carpena, A.L.; Ramos, J.M.; Brar, D.S.
Philippine Journal of Crop Science 39(1): 1-10
Eight out of 20 alien introgression lines (AILs) including the Philippine National Seed Industry Council recommended rice variety Matatag 9, from crosses of rice variety IR64 with five accessions of Oryza rufipogon, were found resistant to tungro infection under field conditions. Subsequent enzyme-linked immunosorbent assay (ELISA) showed that two of these visually-observed resistant AILs were resistant (up to 30% infection) to both rice tungro spherical virus (RTSV) and rice tungro bacilliform virus (RTBV), causing the rice tungro disease. Introgressions in the AILs was analyzed using 142 simple sequence repeats (SSR) markers which showed 73-80 (51-56%) polymorphism between IR64 and five accessions of O. rufipogon. Introgressions from O. rufipogon based on these markers ranged 4-16%. IR84680-74-2-B-B-B observed to be resistant in the field and by ELISA showed 5% (4/79 markers) introgressions from O. rufipogon only on chromosome 3. Matatag showed 9% (7/78 markers) introgressions from its O. rufipogon parent which were distributed on chromosomes 1, 3, 7 and 12. The markers identified in resistant lines may potentially tag novel quantitative trait loci (QTL) for resistance to rice tungro disease (RID) which could be of great value for further elucidation of the molecular genetic control of the traits investigated. These markers can be further validated in a mapping population and can be used for fine mapping QTLs, and eventually use in MAS to accelerate breeding tungro tolerant varieties.