gibberellinit

Gibberellinit, or gibberellins, are a large family of diterpenoid plant hormones that regulate various aspects of growth and development in plants. They are produced in many tissues, including seeds, young leaves, and developing shoots, and they influence processes such as germination, stem elongation, flowering, and fruit development. Different gibberellins vary in activity depending on species and context.

The gibberellin group was named after the fungal species Gibberella fujikuroi, whose infection causes the bakanae or foolish seedling disease in rice. In 1926, Japanese researchers Sumiki and Kurosawa isolated active principles from the fungus and demonstrated their strong growth-promoting effects in plants. Over time, many gibberellins have been identified, with GA1, GA3, GA4, and GA7 among the most studied active forms. GA3 is the most widely used form in agriculture.

Biosynthesis and signaling involve a terpene-based pathway that builds the ent-kaurane skeleton, followed by oxidation steps catalyzed by GA20-oxidase and GA3-oxidase to produce bioactive gibberellins. Perception occurs via the GID1 receptor, and GA binding promotes the ubiquitin-mediated degradation of DELLA proteins, which are growth repressors. This relief of repression triggers transcriptional networks that drive growth and developmental transitions. Gibberellin activity is modulated by interactions with other hormones, notably abscisic acid and auxins.

Applications and regulation: Gibberellins are used in agriculture and horticulture to stimulate seed germination, seedling vigor, stem elongation, and fruit enlargement, and to break dormancy in some seeds. Usage is subject to regulatory oversight, with specific formulations and crop-to-crop guidelines in many regions.