QTL Genomics Research Center, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
Theor Appl Genet. 2011 Nov;123(7):1133-43. doi: 10.1007/s00122-011-1654-0. Epub 2011 Jul 26.
Heading date is the one of the most important traits in rice breeding, because it defines where rice can be cultivated and influences the expression of various agronomic traits. To examine the inhibition of heading by Heading date 2 (Hd2), previously detected on the distal end of chromosome 7's long arm by quantitative trait locus (QTL) analysis, we developed backcross inbred lines (BILs) from Koshihikari, a leading Japanese cultivar, and Hayamasari, an extremely early heading cultivar. The BILs were cultivated under natural field conditions in Tsukuba Japan, and under long-day (14.5 h), extremely long-day (18 h), and short-day (10 h) conditions. Combinations of several QTLs near Hd1, Hd2, Ghd7, Hd5, and Hd16 were detected under these four conditions. Analysis of advanced backcross progenies revealed genetic interactions between Hd2 and Hd16 and between Hd2 and Ghd7. In the homozygous Koshihikari genetic background at Hd16, inhibition of heading by the Koshihikari allele at Hd2 was smaller than that with the Hayamasari Hd16 allele. Similarly, in the homozygous Koshihikari genetic background at Ghd7, the difference in heading date caused by different alleles at Hd2 was smaller than in plants homozygous for the Hayamasari Ghd7 allele. Based on these results, we conclude that Hd2 and its genetic interactions play an important role in controlling heading under long-day conditions. In addition, QTLs near Hd2, Hd16, and Ghd7, which are involved in inhibition of heading under long-day conditions, function in the same pathway that controls heading date.
生育期是水稻育种中最重要的特征之一，因为它决定了水稻可以在哪里种植，并影响各种农艺性状的表达。为了研究在长日条件下通过Heading date 2（Hd2）抑制抽穗的现象，我们利用数量性状位点（QTL）分析在第 7 号染色体长臂的远端检测到的Heading date 2（Hd2），从日本主要品种越光（Koshihikari）和极早生品种早山（Hayamasari）中培育回交自交系（BILs）。BILs 在日本筑波的自然田间条件下以及长日（14.5 小时）、超长日（18 小时）和短日（10 小时）条件下进行了种植。在这四种条件下，在 Hd1、Hd2、Ghd7、Hd5 和 Hd16 附近检测到了几个 QTL 的组合。对高级回交后代的分析表明，Hd2 与 Hd16 之间以及 Hd2 与 Ghd7 之间存在遗传相互作用。在 Hd16 处的纯合越光遗传背景下，Hd2 处的越光等位基因对抽穗的抑制作用小于 Hayamasari Hd16 等位基因。同样，在 Ghd7 处的纯合越光遗传背景下，Hd2 处不同等位基因引起的抽穗日期差异小于 Ghd7 处的 Hayamasari 等位基因纯合植株。基于这些结果，我们得出结论，Hd2 及其遗传相互作用在长日条件下控制抽穗起着重要作用。此外，在长日条件下参与抑制抽穗的 Hd2、Hd16 和 Ghd7 附近的 QTL 在控制抽穗日期的同一途径中起作用。
