种子萌发的抑制调控机制

Repression regulations of seed germination

种子萌发是植物生命周期中一个重要的生理过程,激素作用、miRNA抑制、mRNA区域化、表观遗传调控等多个层次的分子抑制参与该过程的调控。赤霉素(解除抑制的激素)合成和失活的调控主要发生在转录水平,而脱落酸(引起抑制的激素)信号转导途径的调控则通过蛋白质抑制物的降解来实现。miRNA在转录后水平使其靶基因的mRNA降解,抑制种子的萌发;通过mRNA的区域化抑制与萌发相关基因的翻译属于另一层次的转录后抑制;小RNA介导的表观遗传机制也可能在种子萌发过程基因表达的协同调控中发挥重要作用。与分子水平的抑制类似,胚乳和种皮产生的机械抑制也很重要。

Seed germination is an important physiological process in plant life cycle.Multiple levels of repressions,which include hormone effect,miRNA repression,mRNA compartmentaion,epigenetic regulation,are involved in the control of this process.Regulation of gibberellin（a repression removing hormone） synthesis and deactivation is mainly at transcriptional level;while degradation of repressor proteins is a central mechanism of abscisic acid（a repression inducing hormone） signal transduction in seed dormancy and germination.miRNAs are involved in the repression of their target genes at the mRNA level during seed germination.Compartmentation of mRNAs,which represses the translation of germination-related genes under unfavorable conditions,is another level of post-transcriptional repression.Epigenetic mechanism mediated by small RNA may also play important roles in the regulation of coordinate gene expression during seed germination.Mechanic repression imposed by surrounding tissues such as the endosperm and testa is as important as repression at molecular level for seed germination.