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Abscisic acid in the thermoinhibition of lettuce seed germination and enhancement of its catabolism by gibberellin

TLDR
It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.
Abstract
Germination of lettuce (Lactuca sativa L. cv. 'Grand Rapids') seeds was inhibited at high temperatures (thermoinhibition). Thermoinhibition at 28 degrees C was prevented by the application of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis. At 33 degrees C, the sensitivity of the seeds to ABA increased, and fluridone on its own was no longer effective. However, a combined application of fluridone and gibberellic acid (GA3) was able to restore the germination. Exogenous GA3 lowered endogenous ABA content in the seeds, enhancing catabolism of ABA and export of the catabolites from the intact seeds. The fluridone application also decreased the ABA content. Consequently, the combined application of fluridone and GA3 decreased the ABA content to a sufficiently low level to allow germination at 33 degrees C. There was no significant temperature-dependent change in endogenous GA1 contents. It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.

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Journal ArticleDOI

Abscisic acid biosynthesis and catabolism

TL;DR: Identification of ABA metabolic genes has revealed that multiple metabolic steps are differentially regulated to fine-tune the ABA level at both transcriptional and post-transcriptional levels.
Journal ArticleDOI

Plant hormone interactions during seed dormancy release and germination

TL;DR: This review focuses mainly on eudicot seeds, and on the interactions between abscisic acid (ABA), gibberellins (GA), ethylene, brassinosteroids, auxin and cytokinins in regulating the interconnected molecular processes that control dormancy release and germination.
Journal ArticleDOI

CYP707A1 and CYP707A2, Which Encode Abscisic Acid 8′-Hydroxylases, Are Indispensable for Proper Control of Seed Dormancy and Germination in Arabidopsis

TL;DR: It is shown that the cyp707a1 mutant accumulated ABA to higher levels in dry seeds than the cyP707a2 mutant, and each CYP707A gene plays a distinct role during seed development and postgermination growth.
References
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Book

Seeds: Ecology, Biogeography, and, Evolution of Dormancy and Germination

TL;DR: A Geographical Perspective on Germination Ecology: Tropical and Sub-tropical Zones as discussed by the authors, Temperate and Arctic Zones, and Semi-Arctic Zones: Temperate, Subtropical, and Arctic zones.
Journal ArticleDOI

Seed Germination and Dormancy.

TL;DR: This review provides both an overview of the essential processes that are associated with germination and a description of the possible impediments thereto that may result in dormancy.
Journal ArticleDOI

GROWTH RETARDANTS: Effects on Gibberellin Biosynthesis and Other Metabolic Pathways

TL;DR: Plant growth retardants are applied in agronomic and horticultural crops to reduce unwanted longitudinal shoot growth without lowering plant productivity by inhibiting gibberellin (GA) biosynthesis.
Book

Biochemistry and Molecular Biology of Plant Hormones

TL;DR: This book provides up-to-date coverage at an advanced level of a range of topics in the biochemistry and molecular biology of plant hormones, with particular emphasis on biosynthesis, metabolism and mechanisms of action.
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