Rice grain width and shape play a crucial role in determining grain quality and yield. The genetic basis of rice grain width was dissected into six additive quantitative trait loci (QTL) and 11 pairs of epistatic QTL using an F7 recombinant inbred line (RIL) population derived from a single cross between Asominori (japonica) and IR24 (indica). QTL by environment interactions were evaluated in four environments. Chromosome segment substitution lines (CSSLs) harboring the six additive effect QTL were used to evaluate gene action across eight environments. A major, stable QTL, qGW-5, consistently decreased rice grain width in both the Asominori/IR24 RIL and CSSL populations with the genetic background Asominori. By investigating the distorted segregation of phenotypic values of rice grain width and genotypes of molecular markers in BC4F2 and BC4F3 populations, qGW-5 was dissected into a single recessive gene, gw-5, which controlled both grain width and length–width ratio. gw-5 was narrowed down to a 49.7-kb genomic region with high recombination frequencies on chromosome 5 using 6781 BC4F2 individuals and 10 newly developed simple sequence repeat markers. Our results provide a basis for map-based cloning of the gw-5 gene and for marker-aided gene/QTL pyramiding in rice quality breeding.
稻粒寬度和形狀在谷物質(zhì)量和產(chǎn)量決定中發(fā)揮重要作用。通過對(duì)來源于Asominori（japonica）和IR24(indica)的單雜交系的F7重組自交系（RIL）群體的研究發(fā)現(xiàn)，稻粒寬度的遺傳基礎(chǔ)是六個(gè)額外的數(shù)量性狀位點(diǎn)（QTL）以及11對(duì)顯性上位QTL。通過4種環(huán)境評(píng)估QTL與環(huán)境的交互作用。含有六個(gè)具有累加效應(yīng)QTL的染色體片段置換系（CSSLs）用于評(píng)估基因同環(huán)境之間的交互作用。qGW-5是一個(gè)主要的、穩(wěn)定的QTL，總能降低Asominori/IR24 RIL和Asominori背景的CSSL群體的谷粒寬度。通過研究BC4F2和BC4F3種群稻粒寬度表型值的不均等分離比和分子標(biāo)記的基因型發(fā)現(xiàn)，qGW-5被分割成一個(gè)單獨(dú)的隱性基因gw-5，后者同時(shí)控制稻粒寬度和長(zhǎng)寬比。gw-5位于基因組49.7kb的一個(gè)狹窄區(qū)域，此區(qū)域位于5號(hào)染色體上，用6781 BC4F2個(gè)體和10種新發(fā)展的簡(jiǎn)單重復(fù)序列標(biāo)記研究顯示該區(qū)域具有較高的重組頻率。我們的結(jié)果提供了基于繪圖的gw-5基因克隆以及通過分子標(biāo)記協(xié)助基因或QTL控制水稻質(zhì)量育種的基本方法。