Molecular Genetics of the Yabby Gene Family

[77984] bowman维管植物的大多数侧边器官本质上是极性的，它们的近端-远端和背轴-近轴（背-腹或叶顶对叶底）都表现出不对称。例如，在被子植物叶片中，这种不对称通常表现为近-远轴叶片远端较宽而叶柄近端较窄，以及近-近轴细胞类型的形态和分布差异。这一建议的重点是在侧面器官中建立轴向-轴向极性。具体来说，一种分子遗传学方法来阐明细胞命运是如何在侧面器官的背面区域被指定的，将集中在YABBY基因家族成员的作用上。研究表明，该家族的创始成员CRC对心皮中细胞的背面命运的规范是必需的，而YABBY基因家族的其他成员在顶端分生组织产生的所有侧壁器官中都促进了细胞的背面命运。这一结论是基于对结直肠癌功能等位基因的缺失和获得以及YABBY基因家族其他成员功能等位基因的获得的遗传分析得出的。本建议的目的有三个方面。首先，YABBY基因家族的四个成员，其功能似乎有助于侧面器官中下轴细胞命运的规范，将被描述为具体评估基因家族成员的共同和独特功能。其次，将进行旨在阐明YABBY基因家族成员与促进近轴细胞命运的基因和其他促进下轴细胞命运的基因之间的遗传关系的实验。第三，在侧面器官中操纵极性的能力应该允许评估侧面器官与其衍生的分生组织之间的相互作用。特别地，我们将讨论完全由下胚芽组成的侧枝器官对顶端分生组织的影响。这些实验将有助于更好地理解极性是如何在发育中的侧壁器官中建立和维持的。

0077984BowmanMost lateral organs of vascular plants are polar in nature, exhibiting asymmetries in both their proximo-distal and abaxial-adaxial (dorso-ventral or top of the leaf versus the bottom of the leaf) axes. For example, in angiosperm leaves these asymmetries are often manifested as a broad distal blade and a narrower proximal petiole in the proximo-distal axis and differences in the morphology and distribution of cell types in the abaxial-adaxial axis. This proposal is focused on the establishment of abaxial-adaxial polarity in lateral organs. Specifically, a molecular genetic approach to elucidate how cell fate is specified in the abaxial regions of lateral organs will be focused on the roles of members of the YABBY gene family. It has been shown that CRC, the founding member of the family, is required for the specification of abaxial cell fate in the carpels, and that other members of the YABBY gene family promote abaxial cell fate in all lateral organs produced from the apical meristem. This conclusion was based on genetic analyses of both loss and gain of function alleles of CRC and gain of function alleles of other members of the YABBY gene family.The aims of the present proposal are three fold. First, four members of the YABBY gene family whose functions appear to contribute to the specification of abaxial cell fate in lateral organs, will be characterized specifically assessing the shared and unique functions of members of the gene family. Second, experiments aimed at elucidating the genetic relationships between members of the YABBY gene family and genes that promote adaxial cell fates and other genes that promote abaxial cell fate will be undertaken. Third, the ability to manipulate polarity in lateral organs should allow an assessment of interactions between lateral organs and the meristems from which they are derived. In particular, the effect of lateral organs consisting entirely of abaxial fates on the fate of the apical meristem will be followed. These experiments should lead to a better understanding of how polarity is established and maintained in developing lateral organs.