The homeotic gene long sterile lemma (G1) specifies sterile lemma identity in the rice spikelet
The homeotic gene long sterile lemma (G1) specifies sterile lemma identity in the rice spikelet
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DOI：
10.1073/pnas.0907896106
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发表时间：
2009-11
期刊：
影响因子：
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通讯作者：
A. Yoshida;Takuya Suzaki;Wakana Tanaka;H. Hirano
中科院分区：
文献类型：
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作者：
A. Yoshida;Takuya Suzaki;Wakana Tanaka;H. Hirano
花器官特化的机制在被子植物中基本上是保守的，如ABC模型所示。相比之下，调节特定于一组物种的器官或结构发育的机制仍然不清楚。草具有独特的花序单位，包括小穗和小花。在稻属（稻）中，单个小穗由一个外稃和一个内稃，两个不育外稃和不发育颖片包着的一个可育小花组成。每个不育外稃是一个微小的颖片状器官，表面光滑。在这里，我们已经研究了一个长不育外稃1（g1）突变体，其中不育外稃扩大像外稃。详细的表型分析表明，在g1突变体的大不育外稃似乎是由同源异型转化的不育外稃到外稃，表明G1参与抑制外稃身份，指定不育外稃。基因分离表明，G1是一个植物特异性基因家族的成员，该基因家族编码具有先前未表征结构域的蛋白质，在此命名为ALOG（拟南芥LSH 1和水稻G1）。G1 mRNA在不育外稃原基的整个发育过程中表达，G1蛋白定位于细胞核。使用酵母GAL4系统的反式激活试验表明，G1参与转录调控。抑制外稃身份的G1是一致的假说提出来解释水稻小穗的形态进化。我们还表明，野生稻种，Oryza grandiglumis，形成大不育外稃有严重的G1基因突变。
The mechanism of floral organ specification is principally conserved in angiosperms, as demonstrated by the ABC model. By contrast, mechanisms that regulate the development of organs or structures specific to a group of species remain unclear. Grasses have unique inflorescence units, comprising spikelets and florets. In the genus Oryza (rice), the single spikelet consists of a fertile floret subtended by a lemma and a palea, two sterile lemmas, and rudimentary glumes. Each sterile lemma is a tiny glume-like organ with a smooth surface. Here, we have examined a long sterile lemma1 (g1) mutant, in which the sterile lemma is enlarged like the lemma. Detailed phenotypic analysis reveals that the large sterile lemma in the g1 mutant appears to be caused by homeotic transformation of the sterile lemma into a lemma, suggesting that G1 is involved in the repression of lemma identity to specify the sterile lemma. Gene isolation reveals that G1 is a member of a plant-specific gene family that encodes proteins with a previously uncharacterized domain, named here ALOG (Arabidopsis LSH1 and Oryza G1). G1 mRNA is expressed in sterile lemma primordia throughout their development, and G1 protein is localized in the nucleus. A trans-activation assay using the yeast GAL4 system suggests that G1 is involved in transcriptional regulation. Repression of lemma identity by G1 is consistent with a hypothesis proposed to explain the morphological evolution of rice spikelets. We also show that a wild rice species, Oryza grandiglumis, that forms large sterile lemmas has serious mutations in the G1 gene.