Molecular mechanisms and hormonal regulation underpinning morphological dormancy: a case study using Apium graveolens (Apiaceae).
Molecular mechanisms and hormonal regulation underpinning morphological dormancy: a case study using Apium graveolens (Apiaceae).
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DOI：
10.1111/tpj.15489
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发表时间：
2021-09
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通讯作者：
M. Walker;Marta Pérez;Tina Steinbrecher;F. Gawthrop;I. Pavlović;O. Novák;D. Tarkowská;M. Strnad;F. Marone;K. Nakabayashi;G. Leubner‐Metzger
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作者：
M. Walker;Marta Pérez;Tina Steinbrecher;F. Gawthrop;I. Pavlović;O. Novák;D. Tarkowská;M. Strnad;F. Marone;K. Nakabayashi;G. Leubner‐Metzger
未发育（小）的胚胎嵌入丰富的胚乳组织中，从而具有形态（MD）或形态生理（MPD）休眠，被认为是种子休眠进化中的祖先状态。这一特性在Apiaceae家族中保留下来，为研究其基础机制提供了良好的模型系统。采用创新成像、胚胎生长、激素代谢定量、激素和细胞壁相关基因表达分析相结合的方法对Apium graveolens（芹菜）MD进行了研究。综合试验结果表明，芹菜果实胚的发育与胚乳降解有关，胚根萌发需要一个临界胚大小。这些过程的调控依赖于胚胎产生赤霉素和吲哚-3-乙酸（IAA）的基因表达和果室间的串扰。脱落酸（ABA）的降解与ABA敏感性的不同时空模式有关，控制着胚的生长、胚乳的破裂和胚根的萌发。赤霉素、IAA和ABA代谢之间的复杂相互作用，以及对这些激素的组织特异性敏感性的变化，与非md种子不同。我们得出结论，MD果实中胚达到临界大小和相关胚乳破裂构成了一个独特的萌发程序。
Underdeveloped (small) embryos embedded in abundant endosperm tissue, and thus having morphological (MD) or morphophysiological (MPD) dormancy, are considered to be the ancestral state in seed dormancy evolution. This trait is retained in the Apiaceae family which provides excellent model systems to study the underpinning mechanisms. We investigated Apium graveolens (celery) MD by combined innovative imaging and embryo growth assays with the quantification of hormone metabolism, as well as the analysis of hormone and cell-wall related gene expression. The integrated experimental results demonstrated that embryo growth occurred inside imbibed celery fruits in association with endosperm degradation, and that a critical embryo size was required for radicle emergence. The regulation of these processes depends on gene expression leading to gibberellin and indole-3-acetic acid (IAA) production by the embryo and on crosstalk between the fruit compartments. Abscisic acid (ABA) degradation associated with distinct spatiotemporal patterns in ABA sensitivity control embryo growth, endosperm breakdown and radicle emergence. This complex interaction between gibberellins, IAA and ABA metabolism, and changes in the tissue-specific sensitivities to these hormones is distinct from non-MD seeds. We conclude that the embryo growth to reach the critical size and the associated endosperm breakdown inside MD fruits constitute a unique germination programme.