Dissection and fine-mapping of two QTL for grain size linked in a 460-kb region on chromosome 1 of rice.
Dissection and fine-mapping of two QTL for grain size linked in a 460-kb region on chromosome 1 of rice.
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DOI：
10.1186/s12284-018-0236-z
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发表时间：
2018-08-02
期刊：
影响因子：
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通讯作者：
Zhuang JY
中科院分区：
文献类型：
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作者：
Dong Q;Zhang ZH;Wang LL;Zhu YJ;Fan YY;Mou TM;Ma LY;Zhuang JY
水稻籽粒大小是决定粒重的重要因素，也是影响稻米品质的重要性状。虽然越来越多的证据表明微效QTL在控制复杂性状中的重要性，但直到最近才对粒度给予关注。在以往的研究中，利用籼稻杂交组合珍汕97/珍汕97//密阳46的群体，在第1染色体长臂上分离到了5个对籽粒大小影响较小的QTL。其中一个，qTGW1.2c，位于2.1 Mb区域，是本研究中精细定位的目标。首先，qTGW1.2c区域缩小到1.1 Mb的交叉区域，通过确定基因型，使用新开发的多态性标记。然后，鉴定了一个仅在更新的QTL区域中杂合的BC 2F 9植物。从BC 2F 11：12到BC 2F 15：16共衍生了12个群体并用于QTL定位。在460-kb的区域中分离到两个连锁的QTL。qGS 1 -35.2被划分为一个57.7 kb的区域，包含6个注释基因，其中5个在两个亲本系之间表现出核苷酸多态性。定量实时PCR检测到qGS 1 -35.2在6个注释基因中的3个的近等基因系之间的表达差异。该QTL对粒长和粒宽的作用方向相反，对粒长宽比的作用显著，但对产量性状的影响不大。另一个QTL qGW 1 -35.5位于125.5kb的区域内，主要控制粒宽，从而影响粒重。本研究为进一步克隆两个在水稻育种中具有潜在应用价值的粒重微效QTL奠定了基础。qGS 1 -35.2对粒形有影响，但对产量影响不大，可用于改良籽粒外观品质，而qGW 1 -35.5对粒大和粒重均有贡献，为提高籽粒产量提供了新的基因资源。本文的在线版本（10.1186/s12284-018-0236-z）包含补充材料，可供授权用户使用。
Grain size is a key determinant of grain weight and a trait having critical influence on grain quality in rice. While increasing evidences are shown for the importance of minor-effect QTL in controlling complex traits, the attention has not been given to grain size until recently. In previous studies, five QTL having small effects for grain size were resolved on the long arm of chromosome 1 using populations derived from indica rice cross Zhenshan 97///Zhenshan 97//Zhenshan 97/Milyang 46. One of them, qTGW1.2c that was located in a 2.1-Mb region, was targeted for fine-mapping in the present study. Firstly, the qTGW1.2c region was narrowed down into 1.1 Mb by determining genotypes of the cross-over regions using polymorphic markers newly developed. Then, one BC2F9 plant that was only heterozygous in the updated QTL region was identified. A total of 12 populations in generations from BC2F11:12 to BC2F15:16 were derived and used for QTL mapping. Two QTL linked in a 460-kb region were separated. The qGS1-35.2 was delimited into a 57.7-kb region, containing six annotated genes of which five showed nucleotide polymorphisms between the two parental lines. Quantitative real-time PCR detected expression differences between near isogenic lines for qGS1-35.2 at three of the six annotated genes. This QTL affected grain length and width with opposite allelic directions, exhibiting significant effect on ratio of grain length to width but showing little influence on yield traits. The other QTL, qGW1-35.5, was located within a 125.5-kb region and found to primarily control grain width and consequently affect grain weight. Our work lays a foundation for cloning of two minor QTL for grain size that have potential application in rice breeding. The qGS1-35.2 could be used to modify grain appearance quality without yield penalty because it affects grain shape but hardly influences grain yield, while qGW1-35.5 offers a new gene recourse for enhancing grain yield since it contributes to grain size and grain weight simultaneously. The online version of this article (10.1186/s12284-018-0236-z) contains supplementary material, which is available to authorized users.