Written Paper

Molecular characterization of introgression and putative genes for bacterial blight resistance in wide-cross derivatives of rice (Oryza sativa)  [2008]

Hechanova, S.L.S

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A set of 28 advanced alien introgression lines (AILs) derived from crosses of rice (Oryza sativa L.) and five wild species was evaluated for resistance to different races of bacterial blight (BB) prevalent in the Philippines. Wild species showed broad spectrum resistance to ten races of BB of the Philippines, however, derived AILs showed introgression for resistance to only a few races. SSR analysis using markers from chromosomes 5, 6, 8 and 11 which harbor known BB genes revealed 75-82% polymorphism between O. sativa and five wild species (O. longistaminata, O. officinalis, O. minuta and O. brachyantha), however, introgression of wild species was limited to few and small chromosome fragments. Based on previously designed primers linked to BB genes, wild species were found to have different putative genes; Xa4, Xa7 and Xa21 in O. longistaminata, XA4 and Xa7 in O. officinalis acc. 100896 and O. rufipogon acc. 106157, Xa7 in O. officinalis acc. 101399 and Xa4 in O. brachyantha. The AILs derived from O. longistaminata, had Xa4 and Xa7; AILs of O. officinalis showed Xa4, Xa7 and Xa21; and AILs of O. brachyantha had Xa4. O. minuta did not show any of the five genes (Xa4, xa5, Xa7, xa13, Xa21). Based on the SSR analysis and BB reaction of AILs, there are additional genes present in wild species which have not been introgressed into O. sativa gene