gibberellic

Gibberellic is an adjective relating to gibberellins, a family of diterpenoid plant hormones that regulate growth and development in plants. The term originates from Gibberella fujikuroi, a fungus from which the early gibberellins were first identified, and from which gibberellic acid (GA) derives its name.

Gibberellins include several active compounds, among them gibberellic acid (GA3) and others such as GA1, GA4, and GA7. These hormones are produced in seeds, young leaves, and developing shoots of many plants, as well as by certain fungi.

Biological role of gibberellins is diverse. They promote seed germination by triggering the production of hydrolytic enzymes that mobilize food reserves. They also stimulate stem elongation, leaf expansion, flowering, and fruit development, and can help break seed and bud dormancy in some species. The effects are highly context dependent, varying with species, tissue, and environmental conditions.

Mechanism of action involves gibberellins entering plant cells and binding to the GID1 receptor. This interaction promotes the degradation of DELLA proteins, which are growth-repressors, thereby activating growth-related genes and processes.

Biosynthesis begins with terpenoid precursors and proceeds through several steps, including conversion to ent-kaurene and subsequent oxidation to active gibberellins. GA signaling is regulated by environmental cues such as light and temperature, and by developmental stage.

Applications of gibberellins, especially GA3, are widespread in agriculture and horticulture. They are used to enhance seed germination, improve uniformity of growth, induce flowering or fruit set, and enlarge certain fruits in some crops. Regulation and residue limits vary by country, reflecting considerations of safety and agricultural practices.