Gan Yinbo, Kumimoto Rod, Liu Chang, Ratcliffe Oliver, Yu Hao, Broun Pierre
Centre for Novel Agricultural Projects, Department of Biology, University of York, York YO10 5YW, United Kingdom.
Plant Cell. 2006 Jun;18(6):1383-95. doi: 10.1105/tpc.106.041533. Epub 2006 May 5.
As a plant shoot matures, it transitions through a series of growth phases in which successive aerial organs undergo distinct developmental changes. This process of phase change is known to be influenced by gibberellins (GAs). We report the identification of a putative transcription factor, GLABROUS INFLORESCENCE STEMS (GIS), which regulates aspects of shoot maturation in Arabidopsis thaliana. GIS loss-of-function mutations affect the epidermal differentiation of inflorescence organs, causing a premature decrease in trichome production on successive leaves, stem internodes, and branches. Overexpression has the opposite effect on trichome initiation and causes other heterochronic phenotypes, affecting flowering and juvenile-adult leaf transition and inducing the formation of rosette leaves on inflorescence stems. Genetic and gene expression analyses suggest that GIS acts in a GA-responsive pathway upstream of the trichome initiation regulator GLABROUS1 (GL1) and downstream of the GA signaling repressor SPINDLY (SPY). GIS mediates the induction of GL1 expression by GA in inflorescence organs and is antagonized in its action by the DELLA repressor GAI. The implication of GIS in the broader regulation of phase change is further suggested by the delay in flowering caused by GIS loss of function in the spy background. The discovery of GIS reveals a novel mechanism in the control of shoot maturation, through which GAs regulate cellular differentiation in plants.
随着植物茎的成熟，它会经历一系列生长阶段，在此过程中，相继出现的地上器官会发生明显的发育变化。已知这种相变过程受赤霉素（GA）影响。我们报告了一个推定转录因子——无毛花序茎（GIS）的鉴定，它调控拟南芥茎成熟的多个方面。GIS功能缺失突变影响花序器官的表皮分化，导致相继的叶片、茎节间和枝条上的毛状体产生过早减少。过表达对毛状体起始有相反作用，并导致其他异时表型，影响开花和幼叶 - 成叶转变，并在花序茎上诱导莲座叶的形成。遗传和基因表达分析表明，GIS在毛状体起始调节因子无毛1（GL1）上游和GA信号抑制因子细长（SPY）下游的GA响应途径中起作用。GIS介导GA在花序器官中对GL1表达的诱导，并且其作用受到DELLA抑制因子GAI的拮抗。在spy背景下，GIS功能丧失导致的开花延迟进一步表明GIS在相变的更广泛调节中的作用。GIS的发现揭示了茎成熟控制中的一种新机制，通过该机制GA调节植物中的细胞分化。
