Molecular networks regulating Arabidopsis seed maturation, after-ripening, dormancy and germination

Authors


Author for correspondence: Michael J. Holdsworth Tel: +44 1159 516046 Fax: +44 1159 516233 Email: michael.holdsworth@nottingham.ac.uk

Abstract

Contents

 Summary1
I.Introduction2
II.Molecular regulation of seed maturation3
III.After-ripening, transcription and translation during dry seed storage5
IV.Regulation of germination potential following seed imbibition6
V.Other factors influencing dormancy and germination12
VI.Regulation of genome expression in relation to dormancy and germination13
VII.Conclusions15
 Acknowledgements16
 References16

Summary

The transition between dormancy and germination represents a critical stage in the life cycle of higher plants and is an important ecological and commercial trait. In this review we present current knowledge of the molecular control of this trait in Arabidopsis thaliana, focussing on important components functioning during the developmental phases of seed maturation, after-ripening and imbibition. Establishment of dormancy during seed maturation is regulated by networks of transcription factors with overlapping and discrete functions. Following desiccation, after-ripening determines germination potential and, surprisingly, recent observations suggest that transcriptional and post-transcriptional processes occur in the dry seed. The single-cell endosperm layer that surrounds the embryo plays a crucial role in the maintenance of dormancy, and transcriptomics approaches are beginning to uncover endosperm-specific genes and processes. Molecular genetic approaches have provided many new components of hormone signalling pathways, but also indicate the importance of hormone-independent pathways and of natural variation in key regulatory loci. The influence of environmental signals (particularly light) following after-ripening, and the effect of moist chilling (stratification) are increasingly being understood at the molecular level. Combined postgenomics, physiology and molecular genetics approaches are beginning to provide an unparalleled understanding of the molecular processes underlying dormancy and germination.

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