IJPB Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France.
Int J Mol Sci. 2021 May 11;22(10):5069. doi: 10.3390/ijms22105069.
Abscisic acid (ABA) is a key hormone that promotes dormancy during seed development on the mother plant and after seed dispersal participates in the control of dormancy release and germination in response to environmental signals. The modulation of ABA endogenous levels is largely achieved by fine-tuning, in the different seed tissues, hormone synthesis by cleavage of carotenoid precursors and inactivation by 8'-hydroxylation. In this review, we provide an overview of the current knowledge on ABA metabolism in developing and germinating seeds; notably, how environmental signals such as light, temperature and nitrate control seed dormancy through the adjustment of hormone levels. A number of regulatory factors have been recently identified which functional relationships with major transcription factors, such as ABA INSENSITIVE3 (ABI3), ABI4 and ABI5, have an essential role in the control of seed ABA levels. The increasing importance of epigenetic mechanisms in the regulation of ABA metabolism gene expression is also described. In the last section, we give an overview of natural variations of ABA metabolism genes and their effects on seed germination, which could be useful both in future studies to better understand the regulation of ABA metabolism and to identify candidates as breeding materials for improving germination properties.
脱落酸（ABA）是一种关键的激素，它在母株上促进种子发育过程中的休眠，在种子散布后，通过对环境信号的反应，参与休眠解除和萌发的控制。ABA 内源性水平的调节主要通过在不同种子组织中精细调控，通过类胡萝卜素前体的切割来合成激素，并通过 8'-羟化作用失活来实现。在这篇综述中，我们提供了关于发育中和萌发中的种子中 ABA 代谢的最新知识概述；特别是，环境信号（如光、温度和硝酸盐）如何通过调节激素水平来控制种子休眠。最近已经确定了一些调节因子，它们与主要转录因子（如 ABA 不敏感 3 型（ABI3）、ABI4 和 ABI5）的功能关系，在控制种子 ABA 水平方面起着至关重要的作用。在调节 ABA 代谢基因表达方面，表观遗传机制的重要性也在不断增加。在最后一节中，我们概述了 ABA 代谢基因的自然变异及其对种子萌发的影响，这对未来的研究既有用，既可以更好地理解 ABA 代谢的调节，也可以鉴定作为改良萌发特性的育种材料的候选基因。
