Tag: plants: structure and function

 It inhibits root elongation, stem elongation and seed germination. It brings out the stomatal closure when soil water is insufficient to keep up with transpiration. It binds to receptor present on the guard cells and hence closes stomata.

Abscisic acid is a plant hormone. It is involved in various physiological processes of the plant. It acts as a plant growth inhibitor. It is also called as stress hormone as its concentration increases during stress condition. Under the unfavourable condition, it induces seed dormancy. When favourable condition returns, seed dormancy is broken. 

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. It increases the tolerance of plants toward various stresses. It is found in high concentration in roots during drought and later translocated to leaves. It causes stomatal closure during water stress. It also promotes seed dormancy under adverse condition.

Auxin is a plant hormone that is involved in growth and development of plant. Kinetin, a type of cytokinin was isolated from autoclaved herring sperm DNA by Miller and Skoog. Gibberellin hormone was first isolated from fungus Gibberella fujikuroi. Ethylene is a gaseous hormone which helps in ripening process and hence also called as ripening hormone. ABA is responsible for abscission of leaves, fruits and flowers. Florigen is a flowering hormone that is responsible for flowering in certain plants.

Leaf abscission is a detachment or fall of older leaves.It occurs at the base of the petiole. During abscission, high synthesize of abscisic acid is observed along with decrease in the concentration of auxin. ABA loosens the cell wall and cells separate which ultimately leads to leaf abscission. 

Abscisic acid is a plant hormone. It causes abscission of leaves. It induces dormancy of seed under unfavorable condition. Gibberellin is a plant hormone that is an antagonist to the abscisic acid hormone. It regulates plant growth. It stimulates stem elongation, germination, flowering. it breaks the seed dormancy and initiates germination process. 

ABA helps seeds to withstand desiccation and other factors unfavorable for growth.

Abscisic acid inhibits seed germination and stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses. Therefore, it is also called the stress hormone.