Botanical Institute III, University of Cologne, Köln, Germany.
Curr Top Dev Biol. 2010;91:299-321. doi: 10.1016/S0070-2153(10)91010-7.
The aerial organs of plants typically produce trichomes that may adopt various functions, including light, wind, frost, and herbivore protection. Trichomes are of epidermal origin regularly distributed on the surface. The mechanism by which trichome differentiation is triggered in individual cells in a field of protodermal cells is best studied in Arabidopsis thaliana. The genetic analysis has revealed a number of key genes controlling this patterning process, and further molecular analysis has enabled the in-depth cell-biological and biochemical analysis. The established models explain trichome patterning by the mutual interaction between positive and negative factors. Three activators, a bHLH (helix-loop-helix), a R2R3 MYB-related transcription factor, and a WD40 domain protein, form an active complex. The activity of this complex is counteracted by R3 MYB factors that compete with the R2R3 MYB for binding to the bHLH factor. The R3 MYBs can move between cells and thereby mediate cellular interactions. This general model cannot explain all genetic observations and recent data suggest the existence of several parallel patterning mechanisms. In this chapter we aim to summarize the current data and sketch possible alternative, not mutually exclusive theoretical models.
植物的气生器官通常产生表皮毛，这些表皮毛可能具有多种功能，包括避光、防风、抗霜冻和抵御食草动物。表皮毛起源于表皮，在原表皮细胞的表面规则地分布。在拟南芥中，对单个细胞中表皮毛分化是如何在一团原表皮细胞中被触发的这一机制进行了深入研究。遗传分析揭示了控制这一模式形成过程的一些关键基因，进一步的分子分析使深入的细胞生物学和生物化学分析成为可能。已建立的模型通过正、负因素的相互作用来解释表皮毛的模式形成。三个激活子，一个 bHLH（螺旋-环-螺旋），一个 R2R3 MYB 相关转录因子和一个 WD40 结构域蛋白，形成一个活性复合物。该复合物的活性受到 R3 MYB 因子的拮抗，R3 MYB 因子与 R2R3 MYB 竞争与 bHLH 因子结合。R3 MYB 因子可以在细胞间移动，从而介导细胞间的相互作用。这个通用模型不能解释所有的遗传观察结果，最近的数据表明存在几种并行的模式形成机制。在本章中，我们旨在总结当前的数据，并勾勒出可能的替代的、非相互排斥的理论模型。
