Molecular and phenotypic markers for pyramiding multiple traits in rice

Gene pyramiding has been developed for effective resistant genes, such as bacterial blight resistance genes. However, in this report, pyramiding for multiple traits is presented. We evaluated 28 pyramided rice lines derived from 7 hybridizations of valuable parents for high yield potential, early maturity, aroma, high grain quality, and resistance to brown planthopper using both simple-sequence repeat markers and phenotypic markers. Pyramided rice genotypes were evaluated with RM282 molecular marker linked to GW3 gene associated with grain weight, RM259 (number of panicles), RM3600 (length of panicles), RM3701 (short panicles), RM19414 (Hd3), RM7601 (Hd2), RM190, and SSIIa (waxy), IFAP and ESP (aroma), RM586 (Bph3 and Bph4), and RM8213 (Qpbh4 and Bph17(t)). Eight genotypes (i.e., #9, #15, #16, #22, #25, #26, #27, and #28) were confirmed to have desired genes associated with multiple important traits based on molecular markers and morpho-agronomic traits. A strong correlation was found between RM19414 and heading date, between specific markers for aroma and sensory test. Meanwhile, a weak correlation was found between RM259 with panicle number, RM586, and RM8213 with trichome density. As presented in this study, gene pyramiding promises a new hope to combine multiple traits in rice breeding. Promising rice lines will be incorporated in the multiple traits breeding program.