Fambrini Marco, Pugliesi Claudio
Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124 Pisa, Italy.
Plants (Basel). 2019 Jul 28;8(8):253. doi: 10.3390/plants8080253.
Plant trichomes are outgrowths developed from an epidermal pavement cells of leaves and other organs. Trichomes (also called 'hairs') play well-recognized roles in defense against insect herbivores, forming a physical barrier that obstructs insect movement and mediating chemical defenses. In addition, trichomes can act as a mechanosensory switch, transducing mechanical stimuli (e.g., insect movement) into physiological signals, helping the plant to respond to insect attacks. Hairs can also modulate plant responses to abiotic stresses, such as water loss, an excess of light and temperature, and reflect light to protect plants against UV radiation. The structure of trichomes is species-specific and this trait is generally related to their function. These outgrowths are easily analyzed and their origin represents an outstanding subject to study epidermal cell fate and patterning in plant organs. In leaves, the developmental control of the trichomatous complement has highlighted a regulatory network based on four fundamental elements: (i) genes that activate and/or modify the normal cell cycle of epidermal pavement cells (i.e., endoreduplication cycles); (ii) transcription factors that create an activator/repressor complex with a central role in determining cell fate, initiation, and differentiation of an epidermal cell in trichomes; (iii) evidence that underlines the interplay of the aforesaid complex with different classes of phytohormones; (iv) epigenetic mechanisms involved in trichome development. Here, we reviewed the role of genes in the development of trichomes, as well as the interaction between genes and hormones. Furthermore, we reported basic studies about the regulation of the cell cycle and the complexity of trichomes. Finally, this review focused on the epigenetic factors involved in the initiation and development of hairs, mainly on leaves.
植物毛状体是从叶片和其他器官的表皮铺板细胞发育而来的突出物。毛状体（也称为“毛”）在抵御昆虫食草动物方面发挥着公认的作用，形成阻碍昆虫移动的物理屏障并介导化学防御。此外，毛状体可以作为机械传感开关，将机械刺激（例如昆虫移动）转化为生理信号，帮助植物对昆虫攻击做出反应。毛还可以调节植物对非生物胁迫的反应，如水分流失、光照和温度过高，并反射光线以保护植物免受紫外线辐射。毛状体的结构具有物种特异性，这一特征通常与其功能相关。这些突出物易于分析，其起源是研究植物器官中表皮细胞命运和模式的一个杰出课题。在叶片中，毛状体数量的发育控制突出了一个基于四个基本要素的调控网络：（i）激活和/或改变表皮铺板细胞正常细胞周期（即核内复制周期）的基因；（ii）转录因子，其形成激活剂/抑制剂复合物，在决定毛状体中表皮细胞的命运、起始和分化方面起核心作用；（iii）强调上述复合物与不同类别的植物激素相互作用的证据；（iv）参与毛状体发育的表观遗传机制。在这里，我们综述了基因在毛状体发育中的作用，以及基因与激素之间的相互作用。此外，我们报道了关于细胞周期调控和毛状体复杂性的基础研究。最后，本综述重点关注参与毛发生成和发育的表观遗传因素，主要是在叶片上。
