Verification of quantitative trait locus for stickiness of cooked rice and amylose content by developing near-isogenic lines

Abstract

We previously showed a major quantitative trait locus (QTL) for the eating quality of cooked rice (Oryza sativa L.) on the long arm of chromosome 2 using a population of doubled haploid lines derived from crosses between ‘Koshihikari’ and ‘Akihikari’. Here, we verified the effect of QTL by developing near-isogenic lines (NILs). We successfully developed six NILs on the genetic background of Akihikari in which different segments of chromosome 2 were introduced from Koshihikari. On the basis of the measurement of traits related to eating quality, we observed significant differences in the stickiness of cooked rice and amylose content (AC) of grains among NILs. The stickiness scores and AC values of the NILs were negatively correlated. Comparison of the introduced segments with stickiness revealed that the candidate genomic region of chromosome 2 that affects stickiness lies between 515 kbp (defined by the simple sequence repeat (SSR) markers RM13658 and RM3730) and 773 kbp (defined by the SSR markers KA43 and RM6933). These results clearly showed that a chromosome 2 segment introduced from Koshihikari increased stickiness and decreased AC in the NILs, and hence verified the result obtained from the doubled haploid lines.