The Role of KANADI in Promoting Abaxial Cell Fates

种子植物的鲍曼叶由顶端分生组织的侧翼形成。因此，它们之间存在着一种固有的位置关系：器官原基的近轴面靠近分生组织，远轴面远离分生组织。外科和遗传学研究表明，形态发生梯度，其来源是分生组织，将固有的极性转换为功能极性。一旦在器官原基内建立了近轴-远轴的极轴，它就为叶片的正常生长和不对称发育提供了线索。最近发现了参与这一过程的几个关键角色，对这些基因的分析支持并完善了我们关于植物中轴形成的观点。KANADI和YABBY两个基因家族的成员促进远轴命运，它们的表达局限于发育中的侧器官的远轴结构域之上。当近轴因子在背面活跃时，远轴因子的表达被消除，反之亦然。因此，近轴因子和远轴因子在相互排斥的区域中表示。这项建议的目的是描述KANADI的特征，重点是KANADI在抑制纵向因素方面的作用，以及KANADI通过YABBY的活动促进椎板扩张的作用。实验被用来研究KANADI和近轴因子与YABBY之间的相互作用是直接的还是间接的，以及Kanadi依赖的叶片扩张是否是通过Yabby活性介导的。最后，提出了将基于经典分生组织解剖实验的假说与通过遗传学鉴定的基因相结合的实验。提出的基础研究应提供知识基础，以促进植物结构的修改。由于叶片提供了大部分光合作用的来源，因此改变叶片的结构以最大限度地提高这一过程有可能提高许多作物的农业生产力。

0234347BowmanLeaves of seed plants are formed from the flanks of apical meristems. Therefore, an inherent positional relationship exists between them: organ primordia have an adaxial side adjacent to the meristem, and an abaxial one away from the meristem. Surgical and genetic studies suggest that a morphogenetic gradient, whose source is the meristem, converts the inherent polarity into a functional one. Once an adaxial-abaxial axis of polarity is established within organ primordia, it provides cues for proper lamina growth and asymmetric development. Several key players involved in this process were identified recently, and analyses of these genes support and refine our views of axis formation in plants. Members of two gene families, the KANADIs and YABBYs, promote abaxial fates, and their expression is confined top the abaxial domains of developing lateral organs. When adaxial factors are active abaxially, the expression of the abaxial factors is eliminated, and vice versa. Thus, the adaxial and abaxial factors are expressed in mutually exclusive domains. The aim of this proposal is the characterization of the KANADIs, focusing on the role of the KANADIs in repressing adaxial factors, and the role of the KANADIs in promoting lamina expansion through the activity of the YABBYs. Experiments are proposed to address whether the interaction between the KANADIs and the adaxial factors and the YABBYs is direct or indirect and whether KANADI dependent lamina expansion is mediated via YABBY activity. Finally, experiments to integrate hypotheses based on classical meristem dissection experiments with genes identified via genetics are proposed. The basic research proposed should provide a foundation of knowledge to facilitate the modification of plant architecture. Since leaves provide the source of the majority of photosynthate, modification of their structure to maximize this process has the potential to increase agricultural productivity in many crop species.