Gibberelliine

Gibberellins are a class of plant hormones that play a crucial role in various aspects of plant growth and development. They are diterpenoid compounds, meaning they are synthesized from isoprenoid precursors. The gibberellin family comprises over 100 structurally related compounds, with gibberellin A3 (GA3), commonly known as gibberellic acid, being one of the most widely studied and commercially used.

These hormones are synthesized primarily in young leaves, developing seeds, and root tips. They are then transported throughout the plant via the xylem and phloem. Gibberellins function by promoting cell elongation and division, which is essential for stem elongation, leaf expansion, and seed germination. They also influence flowering time, fruit development, and the breaking of dormancy in seeds and buds.

The mechanism of action of gibberellins involves their binding to specific receptor proteins within plant cells. This binding triggers a cascade of molecular events, including the activation of genes responsible for cell wall loosening enzymes and the synthesis of growth-promoting proteins. In agriculture and horticulture, gibberellins are applied exogenously to enhance crop yields, increase fruit size, promote flowering, and improve seed germination rates. Their application needs to be carefully controlled, as excessive levels can lead to undesirable effects like spindly growth.