The temporal and spatial control of meristem identity is a key element in plant development. To better understand the molecular mechanisms that regulate inflorescence and flower architecture, we characterized the rice aberrant panicle organization 2 (apo2) mutant which exhibits small panicles with reduced number of primary branches due to the precocious formation of spikelet meristems. The apo2 mutants also display a shortened plastochron in the vegetative phase, late flowering, aberrant floral organ identities and loss of floral meristem determinacy. Map-based cloning revealed that APO2 is identical to previously reported RFL gene, the rice ortholog of the Arabidopsis LEAFY (LFY) gene. Further analysis indicated that APO2/RFL and APO1, the rice ortholog of Arabidopsis UNUSUAL FLORAL ORGANS, act cooperatively to control inflorescence and flower development. The present study revealed functional differences between APO2/RFL and LFY. In particular, APO2/RFL and LFY act oppositely on inflorescence development. Therefore, the genetic mechanisms for controlling inflorescence architecture have evolutionarily diverged between rice (monocots) and Arabidopsis (eudicots).
分生組織特性的時(shí)空調(diào)控是植物發(fā)育的一個(gè)重要過(guò)程。為了更好了解調(diào)控花序、花型的分子機(jī)制，我們鑒定到了一個(gè)水稻apo2突變體，該突變體表型是小穗型，小穗分生組織提前形成造成其一級(jí)枝梗數(shù)量減少，而且在營(yíng)養(yǎng)生長(zhǎng)時(shí)期，葉生長(zhǎng)間隔期縮短，晚花，花器官特性建立異常，花分生組織建立確定性喪失，圖位克隆表明APO2與之前報(bào)道的RFL基因相同，與擬南芥LEAFY基因同源，進(jìn)一步分析表明APO2/RFL和APO1（與擬南芥UFO同源）協(xié)同起到控制花序和花的發(fā)育。當(dāng)前研究表明水稻APO2/RFL基因和擬南芥LFY基因之間存在功能的差異，尤其是APO2/RFL和LFY在花序發(fā)育上起到相反的作用。因此，在控制花序形態(tài)的分子機(jī)制上，單子葉的水稻和雙子葉的擬南芥進(jìn)化上存在差異。