双子叶植物幼苗顶端弯钩发育的分子机制

Molecular Mechanism of the Development of Dicotyledonous Seedling Apical Hook

幼苗顶端弯钩的形成是双子叶植物暗形态建成过程中的一个重要事件。它保护双子叶植物幼嫩的子叶和脆弱的顶端分生组织在幼苗出土时免受机械损伤,进而保证幼苗的出苗率和成活率。幼苗顶端弯钩的形成是由于下胚轴顶端的两个对立面之间细胞分裂和延伸的不对称所引起的。目前,关于双子叶植物幼苗顶端弯钩发育分子机制的研究已有较大进展:发现生长素在顶端弯钩内外侧组织的梯度分布是顶端弯钩两侧细胞差异生长的重要驱动力;乙烯、赤霉素和油菜素内酯促进顶端弯钩的形成和维持;茉莉酸抑制顶端弯钩的形成;而光照则促进弯钩的打开;无弯钩1(hookless1,HLS1)、乙烯不敏感3以及EIN3相似蛋白1 (ethylene insensitive 3/EIN3 like 1,EIN3/EIL1)、DELLA、组成型光形态发生1(constitutive photomorphogenic 1,COP1)和光敏色素相互作用因子(phytochrome interacting factors,PIFs)等多种因子已被发现参与顶端弯钩的发育过程,并介导了多种激素之间的互作。本文综述了双子叶植物幼苗顶端弯钩发育过程中的重要作用因子及调控网络,并对该领域的研究前景进行了展望。

The formation of seedling apical hook is an important event in the dark morphogenesis of dicotyls. It protects young cotyledons and fragile apical meristem from mechanical damage when the seedlings are unearthed and ensures the emergence rate and the survival rate. The curvature of the apical hook is formed through differential cell division and extension between opposite sides of the upper part of the apical hypocotyl. Nowadays,big process has been made in the understanding of the molecular mechanism underlining the development of the dicotyledonous apical hook. Evidences have shown that the auxin gradient formed between the inner and outer side of the apical hook drives the differential cell growth at different sides in the dark; ethylene, gibberellin and brassinosteroid promote, whereas jasmonate inhibits the formation and maintenance of the apical hook. Outside of the soil,lights trigger the opening of the apical hook. In addition,multiple enzymes,transcription factors and regulators were also found to be involved in the development of the apical hook through integrating different hormones and the environment factors,such as hookless1（ HLS1）,ethylene insensitive 3/EIN3 like 1（ EIN3/EIL1）,DELLA,constitutive photomorphogenic 1（ COP1） and phytochrome interacting factors（ PIFs）. This paper summarized the progress made in recent years about the molecular mechanism controlling thedevelopment of the apical hook. The current limitation and prospect of this research field were also discussed.