CsLFY is required for shoot meristem maintenance via interaction with WUSCHEL in cucumber (Cucumis sativus)

Cucumber (Cucumis sativus; 黄瓜) is an agronomically (农艺) important vegetable (蔬菜) with indeterminant growth habit (无限生长习性), in which leaves are produced from the shoot apical meristem (SAM; 茎尖分生组织), and unisexual flowers (单性花) are generated from the leaf axils (叶腋). LEAFY (LFY) and its homologs have been shown to play important roles in promoting flower development and branching. The LFY homolog gene CsLFY was cloned in cucumber. Molecular biology, developmental biology and biochemical tools were combined to explore the biological function of the LFY homologous gene CsLFY in cucumber. CsLFY was expressed in the SAM, floral meristem and floral organ primordia (原基). Ectopic expression (异位表达) of CsLFY rescued the phenotype of the lfy-5 mutant in Arabidopsis. Knockdown of CsLFY by RNA interference (RNAi) led to defective shoot development and premature discontinuance (过早中止) of leaf initiation in cucumber. Transcription of CsWUS and putative CsLFY target genes including CsAP3 and CUM1 were significantly reduced in the CsLFY-RNAi lines. Further biochemical analyses indicated that CsLFY physically interacts with CsWUS in cucumber. These data suggested that CsLFY has a novel function in regulating shoot meristem maintenance through interaction with CsWUS, and promotes flower development via activation of CsAP3 and CUM1 in cucumber.

黄瓜是农业上比较重要的蔬菜，其具有无限生长的习性，叶是从茎尖分生组织分化而来，单性花是从叶腋分化而来。LEAFY（LFY）基因和其同源基因在促进花发育和分枝中扮演着重要作用。本文克隆了LFY在黄瓜中的同源基因CsLFY，并通过分子生物学、发育生物学和生化的方法对CsLFY在黄瓜中的作用进行了研究。CsLFY在茎尖分生组织、花分生组织和花器官原基中表达。CsLFY在拟南芥lfy-5突变体中的异位表达可以拯救突变体的表型。通过RNA干扰的方法敲低CsLFY的表达会导致黄瓜茎发育缺陷和叶起始 过早中止。在黄瓜CsLFY-RNAi株系中，CsWUS及CsLFY靶基因CsAP3和CUM1的转录显著减少。进一步的生化分析显示黄瓜中CsLFY直接物理上与CsWUS互作。这些数据显示黄瓜CsLFY通过与CsWUS互作在茎尖分生组织的维持上起作用，并且通过激活CsAP3和CUM1促进花的发育。

通讯：张小兰 (http://nxy.cau.edu.cn/art/2012/4/24/art_665_113146.html)

个人简介：1995-1999年，中国农业大学，蔬菜系，学士；1999-2002年，中国农业大学，蔬菜系，硕士；2002-2007年，美国佐治亚大学，植物生物系，博士；2007-2011年，美国加州理工大学，生物系，博士后。

研究方向：蔬菜花和果实发育的分子机理；黄瓜性别决定的分子机制；黄瓜果刺的起始与膨大的基因调控网络。

doi: 10.1111/nph.14954