Zhang Hui, Zhu Yu-Jun, Zhu An-Dong, Fan Ye-Yang, Huang Ting-Xu, Zhang Jian-Fu, Xie Hua-An, Zhuang Jie-Yun
College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China.
State Key Laboratory of Rice Biology and Chinese National Center for Rice Improvement, China National Rice Research Institute, Hangzhou, China.
PeerJ. 2020 Mar 4;8:e8679. doi: 10.7717/peerj.8679. eCollection 2020.
Grain weight is a grain yield component, which is an integrated index of grain length, width and thickness. They are controlled by a large number of quantitative trait loci (QTLs). Besides major QTLs, minor QTLs play an essential role. In our previous studies, QTL analysis for grain length and width was performed using a recombinant inbred line population derived from rice cross TQ/IRBB lines. Two major QTLs were detected, which were located in proximity to and that have been cloned. In the present study, QTLs for grain weight and shape were identified using rice populations that were homozygous at and .
Nine populations derived from the rice cross TQ/IRBB52 were used. An Fpopulation named W1, consisting of 250 families and covering 16 segregating regions, was developed from one residual heterozygote (RH) in the Fgeneration of Teqing/IRBB52. Three near isogenic line (NIL)-F populations, ZH1, ZH2 and ZH3 that comprised 205, 239 and 234 plants, respectively, were derived from three RHs in F. They segregated the target QTL region in an isogenic background. Two NIL populations, HY2 and HY3, were respectively produced from homozygous progeny of the ZH2 and ZH3 populations. Three other NIL-F populations, Z1, Z2 and Z3, were established using three RHs having smaller heterozygous segments. QTL analysis for 1000-grain weight (TGW), grain length (GL), grain width (GW), and length/width ratio (LWR) was conducted using QTL IciMapping and SAS procedure with GLM model.
A total of 27 QTLs distributed on 12 chromosomes were identified. One QTL cluster, // located in the terminal region of chromosome 2, were selected for further analysis. Two linked QTLs were separated in region Tw31911-RM266. was located in Tw31911-Tw32437 and mainly controlled GL and GW. The effects were larger on GL than on GW and the allelic directions were opposite. was located in Tw35293-RM266 and affected TGW, GL and GW with the same allelic direction. Finally, was delimited within a 103-kb region flanked by Tw35293 and Tw35395.
with significant effects on TGW, GL and GW was validated and fine-mapped using NIL and NIL-F populations. These results provide a basis for map-based cloning of and utilization of in the breeding of high-yielding rice varieties.
粒重是产量构成因素之一，是粒长、粒宽和粒厚的综合指标。它们受大量数量性状基因座（QTL）控制。除了主效QTL外，微效QTL也起着至关重要的作用。在我们之前的研究中，利用水稻杂交组合TQ/IRBB品系衍生的重组自交系群体对粒长和粒宽进行了QTL分析。检测到两个主效QTL，它们分别位于已克隆的 和 附近。在本研究中，利用在 和 位点纯合的水稻群体鉴定了粒重和粒形的QTL。
使用了从水稻杂交组合TQ/IRBB52衍生的9个群体。从特青/IRBB52杂交组合F代的一个剩余杂合体（RH）中构建了一个包含250个家系、覆盖16个分离区域的F群体，命名为W1。从F代的3个RH分别衍生出3个近等基因系（NIL）-F群体，即ZH1、ZH2和ZH3，分别包含205、239和234株植株。它们在等基因背景下分离目标QTL区域。从ZH2和ZH3群体的纯合后代分别产生了两个NIL群体，即HY2和HY3。利用3个杂合片段较小的RH构建了另外3个NIL-F群体，即Z1、Z2和Z3。使用QTL IciMapping软件和SAS程序中的GLM模型对千粒重（TGW）、粒长（GL）、粒宽（GW）和长宽比（LWR）进行QTL分析。
共鉴定出分布在12条染色体上的27个QTL。选择位于第2染色体末端区域的一个QTL簇//进行进一步分析。在Tw31911-RM266区域分离出两个连锁QTL。 位于Tw31911-Tw32437区间，主要控制GL和GW。对GL的效应大于对GW的效应，且等位基因方向相反。 位于Tw35293-RM266区间，以相同的等位基因方向影响TGW、GL和GW。最后， 将 定位在Tw35293和Tw35395两侧的103 kb区域内。
利用NIL和NIL-F群体验证并精细定位了对TGW、GL和GW有显著影响的 。这些结果为基于图谱克隆 和在高产水稻品种育种中利用 提供了依据。
