Grain size is the major determinant of grain weight and has an important role in grain quality. It is controlled by several major quantitative trait loci (QTL) and many minor QTL. Identification of QTL for grain size is important for understanding the genetic and molecular network regulating grain size in rice (Oryza sativa L.). Following previous identification of QTL for grain weight and size using an F_2:3 family derived from the indica rice cross Teqing/IRBB52, one QTL, qTGW5, having significant effects on grain length and weight, was targeted for validation, dissection, and fine-mapping. First, the effect of qTGW5 was validated using two near-isogenic line (NIL)-F₂ populations. Then, qTGW5 was dissected into two closely linked QTL using four NIL populations. One of them, qGL5.1, having significant effects on grain length, width, and weight, was located within an 1,896.4-kb region. The other one, qGL5.2, controlling grain length, was further delimited into a 68.8-kb region using seven NIL-F₂ populations. Six annotated genes were found in the qGL5.2 region, of which five showed nucleotide polymorphisms between the two parental lines. Three of the six annotated genes showed significant expression differences between NIL^Teqing and NIL^IRBB52 in young panicles using quantitative real-time polymerase chain reaction. The results will facilitate cloning the minor QTL and understanding the genetic architecture for grain size in rice.

中文翻译：

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水稻5号染色体长臂连锁的两个粒长数量性状位点的解析

粒级是决定粒重的主要决定因素，对品质有重要影响。它受几个主要数量性状基因座（QTL）和许多次要QTL控制。鉴定谷粒大小的 QTL 对于了解调控水稻 ( Oryza sativa L. )谷粒大小的遗传和分子网络具有重要意义。继先前使用源自籼稻杂交 Teqing/IRBB52的 F _2:3家族鉴定出粒重和大小的 QTL 之后，一个 QTL qTGW5对粒长和粒重有显着影响，用于验证、解剖和精细-映射。首先，使用两个近等基因系 (NIL)-F ₂验证了qTGW5的效果人口。然后，使用四个 NIL 种群将qTGW5分解为两个紧密相连的 QTL。其中之一qGL5.1对谷物长度、宽度和重量具有显着影响，位于 1,896.4-kb 区域内。另一个控制谷物长度的qGL5.2使用七个 NIL-F ₂种群进一步划定为 68.8-kb 区域。在qGL5.2区域发现了六个注释基因，其中五个显示两个亲本之间的核苷酸多态性。六个注释基因中的三个在 NIL ^Teqing和 NIL ^IRBB52之间显示出显着的表达差异在幼穗中使用定量实时聚合酶链反应。该结果将有助于克隆次要 QTL 和了解水稻籽粒大小的遗传结构。