Gibberellins and Seed Development in Maize. I. Evidence That Gibberellin/Abscisic Acid Balance Governs Germination versus Maturation Pathways

• Published in: Plant physiology (Bethesda) Vol. 122; no. 4; pp. 1081 - 1088
• Main Authors: Constance N. White, Proebsting, William M., Hedden, Peter, Rivin, Carol J.
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.04.2000; American Society of Plant Biologists
• Subjects: Abscisic Acid - metabolism; Agronomy. Soil science and plant productions; Animal vivipary; Biological and medical sciences; Biosynthesis; Corn; Desiccation; Developmental biology; Economic plant physiology; Embryos; Fructification and ripening; Fructification, ripening. Postharvest physiology; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Germination; Gibberellins; Gibberellins - metabolism; Growth and Development; Hormones; Plant physiology and development; Seed development; Seeds; Seeds - growth & development; Vegetative and sexual reproduction, floral biology, fructification; Vivipary; Zea mays - embryology; Zea mays - metabolism; Monocotyledones; Seeds; Zea mays; Germination; Genetic variant; Gibberellin; Cereal crop; Biological activity; Ripening; Regulation(control); Gramineae; Sesquiterpenes; Angiospermae; Abscisic acid; Development; Plant growth substance; Spermatophyta; Gibberellic acid; Fructification
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.122.4.1081

Abscisic acid (ABA) is required for the regulation of seed maturation in maize (Zea mays L.). Mutants blocked in ABA synthesis (such as viviparous-5) do not mature to quiescent, desiccation-tolerant seeds, but germinate on the ear midway through kernel development. Because gibberellins (GA) and ABA act antagonistically in many aspects of plant development, we hypothesized that ABA antagonizes a positive GA signal for precocious germination in maize. In these experiments, we show that a GA deficiency early in seed development, induced genetically or via biosynthesis inhibitors, suppresses vivipary in ABA-deficient developing kernels. The resulting seeds have both desiccation tolerance and storage longevity. Temporal analysis of GA accumulation in wild-type kernels revealed the accumulation of bioactive $\text{GA}_{1}$ and GA3 prior to the peak in ABA content. We speculate that these GAs stimulate a developmental program leading to vivipary in the absence of normal amounts of ABA, and that a reduction of GA content reestablishes an ABA/GA ratio appropriate for suppression of germination and induction of maturation. In contrast, the induction of a GA deficiency did not suppress vivipary in viviparous-1 mutant kernels, suggesting that VP1 acts downstream of both GA and ABA in programming seed development.