Role of Abscisic Acid in Seed Dormancy |
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Authors: | Allison R Kermode |
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Institution: | (1) Department of Biological Sciences, Simon Fraser University, 8888 University Dr, Burnaby, British Columbia , V5A 1S6, Canada |
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Abstract: | Seed dormancy is an adaptive trait that improves survival of the next generation by optimizing the distribution of germination
over time. The agricultural and forest industries rely on seeds that exhibit high rates of germination and vigorous, synchronous
growth after germination; hence dormancy is sometimes considered an undesirable trait. The forest industry encounters problems
with the pronounced dormancy of some conifer seeds, a feature that can lead to non-uniform germination and poor seedling vigor.
In cereal crops, an optimum balance is most sought after; some dormancy at harvest is favored because it prevents germination
of the physiologically mature grain in the head prior to harvest (that is, preharvest sprouting), a phenomenon that leads
to considerable damage to grain quality and is especially prominent in cool moist environments. The sesquiterpene abscisic
acid (ABA) regulates key events during seed formation, such as the deposition of storage reserves, prevention of precocious
germination, acquisition of desiccation tolerance, and induction of primary dormancy. Its regulatory role is achieved in part
by cross-talk with other hormones and their associated signaling networks, via mechanisms that are largely unknown. Quantitative
genetics and functional genomics approaches will contribute to the elucidation of genes and proteins that control seed dormancy
and germination, including components of the ABA signal transduction pathway. Dynamic changes in ABA biosynthesis and catabolism
elicit hormone-signaling changes that affect downstream gene expression and thereby regulate critical checkpoints at the transitions
from dormancy to germination and from germination to growth. Some of the recent developments in these areas are discussed. |
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Keywords: | Seed development Dormancy Germination Seedling vigor Abscisic acid ABA biosynthesis/catabolism Hormonal cross-talk Signal transduction |
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