Yamaguchi Takahiro, Nagasawa Nobuhiro, Kawasaki Shinji, Matsuoka Makoto, Nagato Yasuo, Hirano Hiro-Yuki
Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Plant Cell. 2004 Feb;16(2):500-9. doi: 10.1105/tpc.018044. Epub 2004 Jan 16.
In this article, we report that carpel specification in the Oryza sativa (rice) flower is regulated by the floral homeotic gene DROOPING LEAF (DL) that is distinct from the well-known ABC genes. Severe loss-of-function mutations of DL cause complete homeotic transformation of carpels into stamens. Molecular cloning reveals that DL is a member of the YABBY gene family and is closely related to the CRABS CLAW (CRC) gene of Arabidopsis thaliana. DL is expressed in the presumptive region (carpel anlagen), where carpel primordia would initiate, and in carpel primordia. These results suggest that carpel specification is regulated by DL in rice flower development. Whereas CRC plays only a partial role in carpel identity, DL may have been recruited to have the more essential function of specifying carpels during the evolution of rice. We also show that DL interacts antagonistically with class B genes and controls floral meristem determinacy. In addition, severe and weak dl alleles fail to form a midrib in the leaf. The phenotypic analysis of dl mutants, together with analyses of the spatial expression patterns and ectopic expression of DL, demonstrate that DL regulates midrib formation by promoting cell proliferation in the central region of the rice leaf.
在本文中，我们报道了水稻花中的心皮特化受花同源异型基因“下垂叶”（DL）调控，该基因不同于著名的ABC基因。DL的严重功能丧失突变导致心皮完全同源异型转变为雄蕊。分子克隆表明，DL是YABBY基因家族的成员，与拟南芥的“蟹爪”（CRC）基因密切相关。DL在假定的心皮原基起始区域（心皮原基）以及心皮原基中表达。这些结果表明，在水稻花发育过程中，心皮特化受DL调控。虽然CRC在心皮特征决定中仅起部分作用，但在水稻进化过程中，DL可能已被招募来发挥指定心皮的更重要功能。我们还表明，DL与B类基因相互拮抗作用，并控制花分生组织的确定性。此外，严重和轻度的dl等位基因在叶片中无法形成中脉。dl突变体的表型分析，以及DL的空间表达模式和异位表达分析表明，DL通过促进水稻叶片中部区域的细胞增殖来调控中脉形成。
