Molecular and cell biological analysis of trichome cell polarity in Arabidopsis

拟南芥叶片毛状体是大型多倍体细胞，具有与叶轴对齐的典型分支模式。分支模式反映了毛细胞的极性，为分离和表征干扰毛形态发生的突变体提供了极好的手段。目前的模型假设拟南芥的毛状体分支是由多细胞毛状体进化而来的，其中周周细胞分裂（平行于叶表面）产生尖刺，偶尔的反斜细胞分裂产生分支。因此，建立正确分支模式极性的机制可能与控制细胞分裂方向的机制有关。这一建议主要集中在四个方面。1)建立携带GFP/RFP等重要报告基因的标记系，监测体内细胞内结构的分布和行为。2)拟南芥多细胞毛体的遗传和细胞生物学分析。3) ANGUSTIFOLIA和STICHEL两个分支基因的分子分析。4) T-DNA标记分支突变体的筛选和分子分析，与法国国立植物研究所合作。

Leaf trichomes in Arabidopsis are large polyploid cells with a stereotype branching pattern that is aligned with respect to the leaf axis. The branching pattern reflects the polarity of the trichome cells and has provided excellent means to isolate and characterize mutants disturbing trichome morphogenesis. Current models assume that trichome branching in Arabidopsis is evolutionary derived from multicellular trichomes in which periclinal cell divisions (parallel to the leaf surface) generate spikes and occasional anticlinal cell divisions initiate branches. In this light, the mechanism establishing the polarity for the correct branching pattern could be related to mechanisms controlling the orientation of cell divisions. This proposal concentrates on 4 aspects. 1) The establishment of marker lines carrying vital reporter like GFP/RFP to monitor the distribution and behavior of intracellular structures in vivo. 2) Genetic and cell biological analysis of Arabidopsis lines displaying multicellular trichomes. 3) Molecular analysis of the two branching genes ANGUSTIFOLIA and STICHEL. 4) Screening and molecular analysis of T-DNA tagged branching mutants in collaboration with the INRA, Versailles.