College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan, China.
State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha, Hunan, China.
PLoS One. 2017 Apr 19;12(4):e0175692. doi: 10.1371/journal.pone.0175692. eCollection 2017.
Panicle traits are among the most important agronomic characters which directly relate to yield in rice. Grain number (GN), panicle length (PL), primary branch number (PBN), and secondary branch number (SBN) are the major components of rice panicle structure, and are all controlled by quantitative trait loci (QTLs). In our research, four advanced backcross overlapping populations (BIL152, BIL196a, BIL196b, and BIL196b-156) carrying introgressed segments from chromosome 6 were derived from an indica/japonica cross that used the super-hybrid rice restorer line HR1128 and the international sequenced japonica cultivar 'Nipponbare' as the donor and recurrent parents, respectively. The four panicle traits, GN, PL, PBN, and SBN, were evaluated for QTL effects using the inclusive composite interval mapping (ICIM) method in populations over two years at two sites. Results showed that a total of twelve QTLs for GN, PL, PBN, and SBN were detected on chromosome 6. Based on marker loci physical positions, the QTLs were found to be tightly linked to three important chromosomal intervals described as RM7213 to RM19962, RM20000 to RM20210, and RM412 to RM20595. Three QTLs identified in this study, PL6-5, PBN6-1, and PBN6-2, were found to be novel compared with previous studies. A major QTL (PL6-5) for panicle length was detected in all four populations at two locations, and its position was narrowed down to a 1.3Mb region on chromosome 6. Near isogenic lines (NILs) carrying PL6-5 will be developed for fine mapping of the QTL, and our results will provide referable information for gene excavation of panicle components in rice.
穗部特征是最重要的农艺性状之一，直接关系到水稻的产量。粒数（GN）、穗长（PL）、一次枝梗数（PBN）和二次枝梗数（SBN）是水稻穗部结构的主要组成部分，均受数量性状位点（QTL）控制。在我们的研究中，四个携带来自第 6 号染色体的渐渗片段的先进回交重叠群体（BIL152、BIL196a、BIL196b 和 BIL196b-156）是由一个籼稻/粳稻杂交种衍生而来的，该杂交种使用超级杂交稻恢复系 HR1128 和国际测序粳稻品种 'Nipponbare' 分别作为供体和轮回亲本。利用包含区间作图（ICIM）方法，在两年两个地点的群体中评估了 GN、PL、PBN 和 SBN 这四个穗部性状的 QTL 效应。结果表明，在第 6 号染色体上共检测到 12 个与 GN、PL、PBN 和 SBN 相关的 QTL。基于标记位点的物理位置，发现这些 QTL 紧密连锁在三个重要的染色体区间，分别为 RM7213 到 RM19962、RM20000 到 RM20210 和 RM412 到 RM20595。本研究鉴定的三个 QTL，PL6-5、PBN6-1 和 PBN6-2，与之前的研究相比是新的。在两个地点的四个群体中均检测到一个控制穗长的主效 QTL（PL6-5），其位置被缩小到第 6 号染色体上的 1.3Mb 区域。携带 PL6-5 的近等基因系（NIL）将被开发用于该 QTL 的精细作图，我们的研究结果将为水稻穗部组成基因的挖掘提供参考信息。
