State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
J Genet Genomics. 2010 Feb;37(2):101-15. doi: 10.1016/S1673-8527(09)60029-1.
Although there is evident homology among reproductive organs when comparing Poaceae (grass) and eudicots, the identity of grass specific organs, such as lodicules, palea, lemma, and glumes has been the subject of a vast and largely inconclusive discussion. Here we provide some direct evidence to support the idea that the empty glumes of rice (Oryza sativa) are counterparts of lemmas. We show that the development of empty glumes is regulated by ELE (elongated empty glume), which belongs to a plant specific novel gene family. Mutations at the ELE locus cause elongated empty glumes, which mimic the lemmas and have the epidermal morphology of lemmas with four or five vascular bundles. As a nuclear-localized gene, ELE is specifically expressed at the empty glumes of immature spikelets, and its ectopic expression causes many floral development defects, including lemma-like palea, extra palea-like structures, elongated lodicules, extra stamens and stigmas. Our result suggests that empty glumes are lemmas of the sterile florets located at the lateral side of the rice spikelet, and ELE acts as a regulator restraining its growth to maintain its small size in wild-type plants.
尽管在比较禾本科（草）和真双子叶植物时，生殖器官具有明显的同源性，但草类特有的器官，如浆片、外稃、内稃和颖片的身份一直是一个广泛而基本上没有定论的讨论主题。在这里，我们提供了一些直接的证据来支持这样一种观点，即水稻（Oryza sativa）的空颖壳是内稃的对应物。我们表明，空颖壳的发育受 ELE（伸长空颖壳）的调控，ELE 属于植物特有的一个新基因家族。ELE 基因座的突变导致伸长的空颖壳，其模仿内稃，并具有四个或五个维管束的内稃表皮形态。作为一个核定位基因，ELE 特异性地在未成熟小穗的空颖壳中表达，其异位表达导致许多花发育缺陷，包括内稃状的外稃、额外的外稃状结构、伸长的浆片、额外的雄蕊和柱头。我们的结果表明，空颖壳是水稻小穗侧面不育小花的内稃，ELE 作为一个调节因子，抑制其生长，以维持其在野生型植物中的小尺寸。
