An Update on the Role of NCED and CYP707A ABA Metabolism Genes in Seed Dormancy Induction and the Response to After-Ripening and Nitrate

AbstractPhysiological dormancy has been described as a physiological inhibiting mechanism that prevents radicle emergence. It can be caused by the embryo (embryo dormancy) as well as by the structures that cover the embryo. One of its functions is to time plant growth and reproduction to the most optimal season and therefore, in nature, dormancy is an important adaptive trait that is under selective pressure. Dormancy is a complex trait that is affected by many loci, as well as by an intricate web of plant hormone interactions. Moreover, it is strongly affected by a multitude of environmental factors. Its induction, maintenance, cycling and loss come down to the central paradigm, which is the balance between two key hormonal regulators, i.e. the plant hormone abscisic acid (ABA), which is required for dormancy induction, and gibberellins (GA), which are required for germination. In this review we will summarize recent developments in dormancy research (mainly) in the model plant Arabidopsis thaliana, focusing on two key players for dormancy induction, i.e. the plant hormone ABA and the DELAY OF GERMINATION 1 (DOG1) gene. We will address the role of ABA and DOG1 in relation to various aspects of seed dormancy, i.e. induction during seed maturation, loss during dry seed afterripening, the rehydrated state (including dormancy cycling) and the switch to germination.

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Seed dormancy and ABA metabolism in Arabidopsis and barley: the role of ABA 8′-hydroxylase

The Plant Journal ◽

10.1111/j.1365-313x.2006.02659.x ◽

2006 ◽

Vol 45 (6) ◽

pp. 942-954 ◽

Cited By ~ 218

Author(s):

Anthony A. Millar ◽

John V. Jacobsen ◽

John J. Ross ◽

Chris A. Helliwell ◽

Andrew T. Poole ◽

...

Keyword(s):

Seed Dormancy ◽

Aba Metabolism

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Abscisic acid and the control of seed dormancy and germination

Seed Science Research ◽

10.1017/s0960258510000012 ◽

2010 ◽

Vol 20 (2) ◽

pp. 55-67 ◽

Cited By ~ 220

Author(s):

Eiji Nambara ◽

Masanori Okamoto ◽

Kiyoshi Tatematsu ◽

Ryoichi Yano ◽

Mitsunori Seo ◽

...

Keyword(s):

Abscisic Acid ◽

High Temperature ◽

Seed Dormancy ◽

Plant Hormone ◽

The Core ◽

Aba Metabolism ◽

External Cues ◽

Aba Content ◽

Seed Dormancy And Germination

AbstractAbscisic acid (ABA) is a plant hormone that regulates seed dormancy and germination. Seeds undergo changes in both ABA content and sensitivity during seed development and germination in response to internal and external cues. Recent advances in functional genomics have revealed the integral components involved in ABA metabolism (biosynthesis and catabolism) and perception, the core signalling pathway, as well as the factors that trigger ABA-mediated transcription. These allow for comparative studies to be conducted on seeds under different environmental conditions and from different genetic backgrounds. This review summarizes our understanding of the control of ABA content and the responsiveness of seeds to afterripening, light, high temperature and nitrate, with a focus on which tissues are involved in its metabolism and signalling. Also described are the regulators of ABA metabolism and signalling, which potentially act as the node for hormone crosstalk. Integration of such knowledge into the complex and diverse events occurring during seed germination will be the next challenge, which will allow for a clearer understanding of the role of ABA.

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ABA Metabolism and Homeostasis in Seed Dormancy and Germination

International Journal of Molecular Sciences ◽

10.3390/ijms22105069 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5069

Author(s):

Naoto Sano ◽

Annie Marion-Poll

Keyword(s):

Seed Dormancy ◽

Current Knowledge ◽

Fine Tuning ◽

Environmental Signals ◽

Hormone Synthesis ◽

Control Seed ◽

Functional Relationships ◽

Aba Metabolism ◽

Natural Variations ◽

Germinating Seeds

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.

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Role of ethylene and proteolytic N‐degron pathway in the regulation of Arabidopsis seed dormancy

Journal of Integrative Plant Biology ◽

10.1111/jipb.13173 ◽

2021 ◽

Author(s):

Xu Wang ◽

Malaika Maraya Gomes ◽

Christophe Bailly ◽

Eiji Nambara ◽

Françoise Corbineau

Keyword(s):

Seed Dormancy ◽

Arabidopsis Seed

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Distribution of seed dormancy classes across a fire-prone continent: effects of rainfall seasonality and temperature

Annals of Botany ◽

10.1093/aob/mcaa203 ◽

2020 ◽

Author(s):

Justin C Collette ◽

Mark K J Ooi

Keyword(s):

Seed Dormancy ◽

Critical Role ◽

Fire Regimes ◽

Common Species ◽

Functional Responses ◽

Stochastic Disturbance ◽

Climate Gradients ◽

Selective Pressures ◽

Rainfall Seasonality

Abstract Background and Aims Different seed dormancy classes control the timing of germination via different cues. The ecological dissimilarities between classes therefore suggest that they are likely to be subject to different selective pressures, and that species within each class will have diverse functional responses. We aimed to investigate this by assessing how variation in the distribution of dormancy classes is correlated with regional environmental factors, in particular rainfall seasonality and temperature. Additionally, we compare the relative proportions of species with physiological (PD) or physical (PY) dormancy to assess whether dormancy class influences their ability to persist under different rainfall seasonality regimes. Methods Dormancy class was assigned for 3990 species from 281 genera occurring across two climate regions, with either winter or aseasonal rainfall, across temperate fire-prone Australia. All regions have similar vegetation and fire regimes. Using a Bayesian framework, we compared the distribution of dormancy classes across temperature and rainfall climate gradients, for threatened and common species. Key Results A high dormant:non-dormant species ratio highlighted the critical role of dormancy across our study regions. Critically, species showing PD were more likely to be threatened in aseasonal rainfall climate regions. Conclusions Our results support the assumption that dormancy is favoured in environments with stochastic disturbance

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Ethylene regulates post-germination seedling growth in wheat through spatial and temporal modulation of ABA/GA balance

Journal of Experimental Botany ◽

10.1093/jxb/erz566 ◽

2019 ◽

Vol 71 (6) ◽

pp. 1985-2004 ◽

Cited By ~ 2

Author(s):

Menghan Sun ◽

Pham Anh Tuan ◽

Marta S Izydorczyk ◽

Belay T Ayele

Keyword(s):

Transcriptional Regulation ◽

Seedling Growth ◽

Molecular Mechanisms ◽

Starch Degradation ◽

Aba Signaling ◽

Temporal Modulation ◽

Aba Metabolism ◽

Radicle Protrusion ◽

Storage Starch

Abstract This study aimed to gain insights into the molecular mechanisms underlying the role of ethylene in regulating germination and seedling growth in wheat by combining pharmacological, molecular, and metabolomics approaches. Our study showed that ethylene does not affect radicle protrusion but controls post-germination endospermic starch degradation through transcriptional regulation of specific α-amylase and α-glucosidase genes, and this effect is mediated by alteration of endospermic bioactive gibberellin (GA) levels, and GA sensitivity via expression of the GA signaling gene, TaGAMYB. Our data implicated ethylene as a positive regulator of embryo axis and coleoptile growth through transcriptional regulation of specific TaEXPA genes. These effects were associated with modulation of GA levels and sensitivity, through expression of GA metabolism (TaGA20ox1, TaGA3ox2, and TaGA2ox6) and signaling (TaGAMYB) genes, respectively, and/or the abscisic acid (ABA) level and sensitivity, via expression of specific ABA metabolism (TaNCED2 or TaCYP707A1) and signaling (TaABI3) genes, respectively. Ethylene appeared to regulate the expression of TaEXPA3 and thereby root growth through its control of coleoptile ABA metabolism, and root ABA signaling via expression of TaABI3 and TaABI5. These results show that spatiotemporal modulation of ABA/GA balance mediates the role of ethylene in regulating post-germination storage starch degradation and seedling growth in wheat.

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