Improvement Of The Cooking And Eating Quality Of Hybrid Rice Xieyou 57 And Contents Of Rice Mapping Of QTLs For The Amylose

Xieyou 57, an elite indica hybrid, owns high yield and wide adaptability. The high amylose content (AC) in the endosperm of both parents, however, results in the high AC of Xieyou 57, and thus relatively poor cooking and eating quality of the hybrid. In this study, we improved 057(the restorer line, designated as 057(GG))and XieqingzaoA(the male-sterile line, designated as XA(GG)) using YH559 and ND42 with moderate AC as the donor parents respectively, and successfully obtained the improved lines of 057(057(TT)) and XA(XA(TT)) by PCR-AccⅠMarker Assisted Selection (MAS), and resultantly made four combinations of crosses-XA(GG)×057(GG), XA(GG)×057(TT), XA(TT)×057(GG), XA(TT)×057(TT). The eating quality, starch pasting properties and granule-bound starch synthase(GBSS) activity of all the four combinations were analysed.A population of 190 recombinan t inbred lines (RIL s) derived f rom a cross between 93-11 and Nipponbare, and 178 pairs of SSR, CAPs and STS makers were used to construct a linkage map. The quantitative traits locis (QTLs) for AC of rice were mapped by Composite Interval Mapping (CIM) in three districts(Hainan. Hefei and Huaiyuan).The results are as follows:1. The improvement of the parents of Xieyou57AC of the improved type of XieqingzaoB(the maintainer line of XieqingzaoA) decreased from 22.9% of the original XieqingzaoB to 13.35%,while AC of the improved type of 057 from 25.3% of the original 057 to 15.35%. Thus, AC of both improve parents were at the moderate level.2. The improvement of the hybrid rice of Xieyou57The yield and other agronomic traits of XA(GG)×057(TT), XA(TT)×057(GG) and XA(TT)×057(TT) showed no significant differences. the AC of the single parent improved hybrids, XA(GG)×057(TT) and XA(TT)×057(GG) are 19.95% and 19.35% respectively, both lower than 26.2% of original Xieyou 57(GG), while XA(TT)×057(GG) with relatively improved eating quality, however, the uniformity was not good enough. the both parents improved XA(TT)×057(TT), not only showed a decreased AC(12.5%), but also had better uniform AC for different seeds and good cooking and eating quality, therefore, the purpose of the improvement was achieved.3. GBSS activityThe GBSS activity was tightly related to AC, and the three Wx genotype showed GG＞GT＞TT. The AC of varieties with Wx-GG genotype was high due to the high GBSS activity and the long peak duration of GBSS activity.4. mapping of QTLs for AC14 QTLs for AC were mapped.10 of them were major QTLs(contribution rate＞20%), located on chromosome 1,3,5,3,8 and 10. qAC-1c, qAC-3a, qAC-3b and qAC-10b(contribution rate:74.6048%-78.6667%) were detected in all the three districts, with good stability.