The Role of YABBY Gene Family Members in Promoting Lamina Expansion

种子植物的侧器官，如叶和花器官，是由顶端分生组织的侧翼形成的。因此，它们之间存在着内在的位置关系：叶原基的正面靠近分生组织，而背轴远离分生组织。外科和遗传学研究表明，以分生组织为来源的信号是诱导近轴同一性所必需的，在没有信号的情况下，背轴命运是默认获得的。随后，不对称的近轴-远轴轴为叶片的正常生长提供了线索。最近发现了参与这一过程的几个关键角色，并提出这些植物特有基因家族(III类HD-zips、YABBY和KANADI)不同成员之间及其内部的复杂关系可能是种子植物侧器官形态变异的重要原因。III类HD-ZIP基因促进正面命运，在分生组织中表达，在侧生器官中正面表达。相反，Kanadi和Yabby基因促进远轴命运，它们的表达仅限于发育中的侧器官的远轴区域。因此，近轴和远轴因子在相互排斥的结构域中表达，这些结构域之间的相互作用是叶片正常发育所必需的。一些证据表明，Yabby基因的活性可能与叶片的发育密切相关。本研究的总体目的是为了更好地了解Yabby的功能，解决Yabby基因家族成员在促进远轴细胞命运和促进叶片发育方面的作用。建议的实验将澄清我们对Yabby在促进远轴细胞命运和叶片发育中的作用的理解。从长远来看，控制叶片等侧器官的大小和形状的能力可能会提高许多作物的生产力。

Lateral organs of seed plants, such as leaves and floral organs, are formed from the flanks of apical meristems. Therefore, an inherent positional relationship exists between them: leaf primordia have an adaxial side adjacent to the meristem, and an abaxial one away from the meristem. Surgical and genetic studies suggest that a signal, whose source is the meristem, is required to induce adaxial identity, and in its absence, abaxial fates are acquired by default. Subsequently, the asymmetric adaxial-abaxial axis provides cues for proper lamina growth. Several key players involved in this process were identified recently, and it has been suggested that complex relationships between and within various members of these plant-specific gene families (class III HD-ZIPs, YABBYs and KANADIs) may account for a significant portion of the morphological variation in lateral organs of seed plants. The class III HD-ZIP genes promote adaxial fates and are expressed in the meristem and adaxially in lateral organs. In contrast, the KANADI and YABBY genes promote abaxial fates, and their expression is confined to the abaxial domains of developing lateral organs. Thus, the adaxial and abaxial factors are expressed in mutually exclusive domains, and interaction between these domains is required for proper leaf lamina development. Several lines of evidence suggest that YABBY gene activity may be intimately involved with the development of the lamina.The overall aim of this proposal is to better understand YABBY function addressing the role of YABBY gene family members in promoting abaxial cell fates and in promoting lamina development. The proposed experiments should clarify our understanding of YABBY function in the promotion of abaxial cell fates and the development of leaf lamina. In the long term, the ability to manipulate the size and shape of lateral organ, such as leaves, could lead to increased productivity of many crop species.