Grigg Stephen P, Canales Claudia, Hay Angela, Tsiantis Miltos
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
Nature. 2005 Oct 13;437(7061):1022-6. doi: 10.1038/nature04052.
Leaves of flowering plants are determinate organs produced by pluripotent structures termed shoot apical meristems. Once specified, leaves differentiate an adaxial (upper) side specialized for light capture, and an abaxial (lower) side specialized for gas exchange. A functional relationship between meristem activity and the differentiation of adaxial leaf fate has been recognized for over fifty years, but the molecular basis of this interaction is unclear. In Arabidopsis thaliana, activity of the class I KNOX (KNOTTED1-like homeobox) genes SHOOTMERISTEMLESS (STM) and BREVIPEDICELLUS (BP) is required for meristem function but excluded from leaves, whereas members of the HD-Zip III (class III homeodomain leucine zipper) protein family function to promote both meristem activity and adaxial leaf fate. Here we show that the zinc-finger protein SERRATE acts in a microRNA (miRNA) gene-silencing pathway to regulate expression of the HD-Zip III gene PHABULOSA (PHB) while also limiting the competence of shoot tissue to respond to KNOX expression. Thus, SERRATE acts to coordinately regulate meristem activity and leaf axial patterning.
开花植物的叶子是由被称为茎尖分生组织的多能结构产生的确定器官。一旦确定，叶子就会分化出专门用于捕获光线的近轴（上）面和专门用于气体交换的远轴（下）面。分生组织活性与近轴叶命运分化之间的功能关系已被认识五十多年，但这种相互作用的分子基础尚不清楚。在拟南芥中，I类KNOX（类KNOTTED1同源异型框）基因无柄分生组织（STM）和短柄（BP）的活性是分生组织功能所必需的，但在叶子中被排除，而HD-Zip III（III类同源异型域亮氨酸拉链）蛋白家族的成员则起到促进分生组织活性和近轴叶命运的作用。在这里，我们表明锌指蛋白锯齿状蛋白在微小RNA（miRNA）基因沉默途径中发挥作用，以调节HD-Zip III基因拟南芥叶背（PHB）的表达，同时还限制茎组织对KNOX表达作出反应的能力。因此，锯齿状蛋白起到协调调节分生组织活性和叶轴向模式形成的作用。
