Ehd2, a Rice Ortholog of the Maize INDETERMINATE1 Gene, Promotes Flowering by Up-Regulating Ehd1
Ehd2, a Rice Ortholog of the Maize INDETERMINATE1 Gene, Promotes Flowering by Up-Regulating Ehd1
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DOI：
10.1104/pp.108.125542
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发表时间：
2008-11-01
期刊：
影响因子：
7.4
通讯作者：
Yano, Masahiro
中科院分区：
文献类型：
--
作者：
Matsubara, Kazuki;Yamanouchi, Utako;Yano, Masahiro
最近对水稻（Oryza sativa）开花的研究揭示了与拟南芥（Arabidopsis thaliana）相比，光周期控制开花的独特和保守的遗传途径。我们发现了一个早抽穗日期2（ehd 2）突变体，显示极晚开花短日和长日条件下的背景缺乏抽穗日期1（Hd 1），水稻康斯坦直向同源物，属于保守的途径。Ehd 2突变体中的这种表型表明Ehd 2在水稻的成花转变中是关键的。基于图位的克隆显示，Ehd 2编码一个假定的转录因子与锌指基序的inhibitate 1（ID 1）基因，促进开花玉米（玉米）。Ehd 2 mRNA在水稻组织中积累最丰富的发育叶片中，但在茎尖周围和根中的水平很低，模式是类似的ID 1。为了在水稻开花途径中分配Ehd 2的位置，我们比较了野生型植物和ehd 2突变体之间先前分离的开花时间基因的转录水平，例如Ehd 1，独特途径的成员Hd 3a和水稻FT样1（RFT 1;水稻成花基因）。在短日照和长日照条件下，Ehd 2中这些基因的表达严重减少，这表明Ehd 2主要通过上调Ehd 1和上调下游Hd 3a和RFT 1基因在水稻光周期开花的独特遗传网络中起开花启动子的作用。
Recent research into the flowering of rice (Oryza sativa) has revealed both unique and conserved genetic pathways in the photoperiodic control of flowering compared with those in Arabidopsis (Arabidopsis thaliana). We discovered an early heading date2 (ehd2) mutant that shows extremely late flowering under both short- and long-day conditions in line with a background deficient in Heading date1 (Hd1), a rice CONSTANS ortholog that belongs to the conserved pathway. This phenotype in the ehd2 mutants suggests that Ehd2 is pivotal for the floral transition in rice. Map-based cloning revealed that Ehd2 encodes a putative transcription factor with zinc finger motifs orthologous to the INDETERMINATE1 (ID1) gene, which promotes flowering in maize (Zea mays). Ehd2 mRNA in rice tissues accumulated most abundantly in developing leaves, but was present at very low levels around the shoot apex and in roots, patterns that are similar to those of ID1. To assign the position of Ehd2 within the flowering pathway of rice, we compared transcript levels of previously isolated flowering-time genes, such as Ehd1, a member of the unique pathway, Hd3a, and Rice FT-like1 (RFT1; rice florigens), between the wild-type plants and the ehd2 mutants. Severely reduced expression of these genes in ehd2 under both short- and long-day conditions suggests that Ehd2 acts as a flowering promoter mainly by up-regulating Ehd1 and by up-regulating the downstream Hd3a and RFT1 genes in the unique genetic network of photoperiodic flowering in rice.