Abstract: The genetic mechanism underlying the relationship between grain weight and its six component traits (grain length, grain width, grain thickness, length/width, grain volume and grain density) in rice was dissected using 292 F₁₃ RILs and a complete linkage map with 272 markers. The RILs showed tremendous transgressive segregation for all traits studied. Grain weight was positively correlated with all other grain traits. Significant negative associations existed between grain width, thickness and grain density, which could be associated with grain quality. Forty-eight main-effect QTLs and 38 epistatic QTL pairs affecting these traits were identified, collectively explaining over 55% of the total variation of individual traits. More than 80% QTLs tended to have pleiotropism or physiological associations. QGl3 and QGl2 had indirect impacts on grain weight via grain volume, at which the Lemont alleles were beneficial for the improvement of grain quality. The Teqing alleles at QGw5, QGt1 and QGv7 increased grain weight but had inverse impacts on grain quality and grain density. Improvement for grain weight as well as grain quality would be practical by recombination of different QTLs using marker-assisted selection.

Key words: rice, grain weight, grain quality, quantitative trait locus, epistasis, marker-assisted selection

摘要： 应用292个 Lemont/ 特青F13重组自交系(RILs)和272个标记的遗传连锁图谱分析粒重及籽粒长、宽、厚、长/宽、体积和容重6个相关性状的遗传。所有性状在RILs中出现超亲分离。粒重与其他籽粒性状均呈显著正相关，而涉及籽粒品质的容重与粒宽、粒厚呈显著负相关。检测到影响粒重及其相关性状的主效QTL 48个和互作位点38对，这些QTL解释了各性状55%以上的表型变异。80%以上的主效QTL呈现一因多效或生理相关。QGl3和 QGl2等通过籽粒体积间接影响粒重， Lemont增效等位基因有利于籽粒品质的改良，而QGw5、QGt1和QGv7的特青增效等位基因增加粒重同时降低籽粒容重及品质。通过标记辅助选择进行不同QTL的重组，有望在增加粒重的同时改善籽粒品质。

关键词: 水稻, 粒重, 籽粒品质, 数量性状位点, 上位性, 标记辅助选择