Department of Biological Sciences, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8654, Japan.
New Phytol. 2017 Jul;215(2):825-839. doi: 10.1111/nph.14617. Epub 2017 May 30.
YABBY genes play important roles in the development of lateral organs such as leaves and floral organs in Angiosperms. However, the function of YABBY genes is poorly understood in monocots. We focused on three rice (Oryza sativa) YABBY genes, TONGARI-BOUSHI (TOB1, TOB2, TOB3), which are closely related to Arabidopsis (Arabidopsis thaliana) FILAMENTOUS FLOWER (FIL). To elucidate the function of these YABBY genes, we employed a reverse genetic approach. TOB genes were expressed in bract and lateral organ primordia, but not in meristems. RNAi knockdown of TOB2 or TOB3 in the tob1 mutant caused abnormal spikelet development. Furthermore, simultaneous knockdown of both TOB2 and TOB3 in tob1 affected not only spikelet, but also inflorescence development. In severe cases, the inflorescences comprised naked branches without spikelets. Analysis of inflorescence development at an early stage showed that the observed phenotypic defects were closely associated with a failure to initiate and maintain reproductive meristems. These results indicate that the TOB genes regulate the maintenance and fate of all reproductive meristems. It is likely that the function of FIL/TOB clade YABBY genes has been conserved between Arabidopsis and rice to maintain the proper function of meristems, even though these genes are expressed in lateral organ primordia.
YABBY 基因在被子植物侧生器官（如叶和花器官）的发育中发挥重要作用。然而，单子叶植物中 YABBY 基因的功能尚不清楚。我们专注于三个水稻（Oryza sativa）YABBY 基因，TONGARI-BOUSHI（TOB1、TOB2、TOB3），它们与拟南芥（Arabidopsis thaliana）FILAMENTOUS FLOWER（FIL）密切相关。为了阐明这些 YABBY 基因的功能，我们采用了反向遗传学方法。TOB 基因在苞片和侧生器官原基中表达，但不在分生组织中表达。TOB2 或 TOB3 的 RNAi 敲低在 tob1 突变体中导致小穗发育异常。此外，同时敲低 tob1 中的 TOB2 和 TOB3 不仅影响小穗，还影响花序发育。在严重情况下，花序由没有小穗的裸枝组成。早期花序发育的分析表明，观察到的表型缺陷与生殖分生组织的起始和维持失败密切相关。这些结果表明，TOB 基因调节所有生殖分生组织的维持和命运。尽管这些基因在侧生器官原基中表达，但拟南芥和水稻中 FIL/TOB 分支 YABBY 基因的功能可能是保守的，以维持分生组织的正常功能。
