The Role of KANADI in Promoting Abaxial Cell Fates

种子植物的叶由顶端分生组织的侧面形成。因此，它们之间存在着一种内在的位置关系：器官原基的近轴侧靠近分生组织，远轴侧远离分生组织。外科和遗传学研究表明，形态发生梯度，其来源是分生组织，将固有的极性转化为功能性极性。一旦近轴-远轴极性轴在器官原基内建立，它就为适当的叶片生长和不对称发育提供了线索。参与这一过程的几个关键参与者最近被确定，对这些基因的分析支持并完善了我们对植物中轴形成的看法。KANADI和YABBYs两个基因家族的成员促进远轴命运，并且它们的表达被限制在发育中的侧器官的远轴域的顶部。 当近轴因子在背轴上活跃时，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域中表达。 该提案的目的是KANADI的表征，重点是KANADI在抑制近轴因子中的作用，以及KANADI通过YABBYs的活性在促进叶片扩张中的作用。 实验提出解决KANADI和近轴因子和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通过YABBY活性介导。 最后，提出了基于经典分生组织解剖实验的假设与通过遗传学鉴定的基因的整合实验。 建议的基础研究应提供一个知识基础，以促进植物结构的修改。 由于叶片提供了大部分光合产物的来源，因此改变其结构以使这一过程最大化具有提高许多作物物种农业生产力的潜力。

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.