Molecular Genetic Characterization of Pathways Involved in Establishing Abaxial Cell Fate in Arabidopsis Carpels

Bowman 9986054虽然在了解发育中花的器官特性的分子机制方面取得了重大进展，但对单个器官内细胞命运特化的机制知之甚少。选择分子遗传学方法来阐明细胞命运是如何在心皮中指定的，最初集中在蟹爪的作用。最近的研究表明，蟹爪是心皮远轴细胞命运的特化所必需的。这一结论是基于对蟹爪的功能丧失和获得等位基因的遗传分析以及与近缘基因家族成员的比较得出的。心皮远轴位置的近轴组织的发育需要两个条件：第一，远轴细胞命运的丧失，第二，促进分生组织生长的基因的抑制作用的丧失。第二个条件必须满足，以便允许胎盘分生组织在心皮的远轴面上发育。这个建议是集中在两个基因，蟹爪和KANADI，似乎独立地采取行动，在一个部分冗余的方式，以促进规范的远轴细胞的命运在内侧区域的心皮。虽然在任一基因的单突变体不显示在心皮极性分化的损失，在蟹爪kanadi双突变体镜像复制的近轴组织发展在心皮的远轴位置。这个建议的总体目标是鉴定和表征在远轴细胞命运的指定或分生潜能的抑制和/或激活中起作用的基因和植物激素

Bowman9986054While significant progress has been made in the understanding of the molecular mechanisms by which organ identity is specified in developing flowers, much less is known about the mechanisms of cell fate specification within individual organs. A molecular genetic approach was chosen to elucidate how cell fate is specified in the carpel, initially focusing on the role of CRABS CLAW. It has recently been shown that CRABS CLAW is required for the specification of abaxial cell fate in the carpels. This conclusion was based on genetic analyses of both loss- and gain-of-function alleles of CRABS CLAW as well as comparisons with closely related gene family members.The development of adaxial tissues in abaxial positions in the carpel requires twoconditions: first, the loss of abaxial cell fate, and second, the loss of suppression of genes promoting meristematic growth. The second condition must be met in order to allow the development of placental meristems on the abaxial surfaces of the carpel. This proposal is focused on two genes, CRABS CLAW and KANADI, that appear to act independently in a partially redundant manner to promote the specification of abaxial cell fate in the medial regions of the carpel. While single mutants in either gene do not display a loss of polar differentiation in the carpel, in crabs claw kanadi double mutants mirror image duplications of adaxial tissues develop in abaxial positions of the carpel. The overall aims of this proposal are to identify and characterize genes andphytohormones that play a role in either specification of abaxial cell fate or suppression and/or activation of meristematic potential