Written Paper

Transfer of resistance to yellow stem borer (Scirpophaga incertulas Walker) from wild species into rice (Oryza sativa L.) and molecular characterization of introgression  [2008]

Du, M.J.C.

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Wild species of Oryza and alien introgression lines (AILs) derived from wide crosses were evaluated for resistance to yellow stem borer (YSB) based on larval mortality and weight, deadheart and whitehead damage. Wild species were resistant to YSB based on cut stem bioassay; O. rufipogon and O. longistaminata showed increased larval mortality and reduced larval weight. Some accessions of O.glaberrima also showed increased larval mortality and tolerance at whitehead stage. Recombinant inbred lines (RILs) derived from O. sativa × O. rufipogon showed increased tolerance to whitehead damage. Of the 249 AILs derived from O. sativa × O. longistaminata, some showed high level of tolerance to YSB at deadheart stage. One of the AILs, IR75082-99-10-2-5-6 was found to be highly tolerant based on deadheart and whitehead damage including high larval mortality and reduced weight. Of the 386 SSR markers tested, 231 (59.84%) were polymorphic and 118 markers detected introgression of O. longistaminata alleles into O. sativa. Analysis of 50 AILs with SSR markers showed 92.7% genome of O. sativa and 6.8% of O. longistaminata. Five main effect QTLs were detected for whitehead on chromosome 7, one each on chromosomes 4 and 11 for larval mortality and two for silica content on chromosome 7 with COD scores of 3.0 to 4.5.