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Uncovering the mystery of gibrelin: How does it affect plant development?
Gibberellins (GA) is a type of plant hormone that plays a vital role by regulating various developmental processes of plants. These processes include stem elongation, seed germination, dormancy, flowering, flower development, and senescence of leaves and fruits. Since the "Green Revolution" of the 1960s, Gibrelin has been widely studied, as its use is considered one of the key factors in saving more than a billion people around the world.
The mechanism by which Gibrelin affects plant development allows us to understand how to improve crop yields through biotechnology.
Chemical Properties
All known gibrelins are diterpenoid acids, compounds synthesized from the terpene metabolic pathways of plants and modified in the endoplasmic reticulum and cytoplasm until they form biologically active forms. Gibberellane is named in the order from GA1 to GAn, and its basic skeleton is ent-gibberellane. As of 2020, 136 gibrelin species from plants, fungi, and bacteria have been identified.
Biological functions
Gibrelin plays an important role in breaking seed dormancy and promoting the natural process of germination. During the early stages of germination, the starch reserves of the seeds provide nutrients to the seedlings. Shortly after the seeds come into contact with water, starch is converted into glucose. Gibrelin is thought to signal starch hydrolysis by inducing the synthesis of alpha-amylase. This process demonstrates how gibrelin promotes starch conversion by stimulating the secretion of lysine adenosylase, thereby providing energy to the seed embryo.
The effects of Gibrelin are not limited to stimulating germination, but can also promote cell elongation, bud growth and the formation of seedless fruits.
Metabolism and synthesis
In higher plants, the synthesis of gibrelin usually comes from the methylred phosphate pathway. The product of this pathway is based on trans-biological cinnamic acid diphosphate (GGDP), which undergoes a multi-step reaction to produce bioactive gibberellin. Its synthesis involves three types of enzymes: terpene synthase, P450 monooxygenase and 2-oxoglutarate-dependent dioxygenase.
Most of the biologically active geberelin is located in the growth organs of plants, which indicates that the synthesis of active geberelin is closely related to its functional region.
Signaling mechanism
How gibrelin works at the molecular level involves multiple molecular interactions. Although the presence of a specific gibrelin receptor on the surface membrane has not yet been confirmed, scientists have identified the soluble receptor GID1. When gibberellin binds to GID1, it changes the structure of the receptor, thereby promoting the degradation of DELLA proteins. The DELLA protein itself is an inhibitor of plant development. When it is degraded, the inhibitory effect on plant growth and development disappears.
Environmental impact on gibrelin
Environmental factors such as light, temperature and pressure can affect gibrelin levels. Studies have shown that cold treatment will promote the synthesis of gibrelin, while excessive environmental stress will reduce the growth rate of plants, which is closely related to the concentration of gibrelin.
Agricultural producers can use the knowledge of gibrelin to adjust the growth time of crops and even change the maturity period of crops.
Applications and future research directions of Gibrelin
With the deepening of the understanding of gibrelin, its applications in agriculture and horticulture have begun to increase, such as accelerating crop adaptability and increasing crop yields. For future research, scientists will focus on uncovering the complex interactions between gibrelin and other plant hormones, and how they work together under different environmental conditions to affect plant growth and development.
How does gibrelin affect the development and growth of plants? What profound impact and implications will this discovery have on our agricultural production methods?
