Plant hormones

Plant Hormones

Plant hormones, also known as phytohormones, are chemical substances that regulate the growth, development, and differentiation of cells and tissues in plants. They are a fundamental part of plant physiology and play a crucial role in the plant's ability to respond to its environment.

Types of Plant Hormones

There are five major types of plant hormones: auxins, gibberellins, cytokinins, abscisic acid (ABA), and ethylene. Each of these hormones has a unique role in plant growth and development.

Auxins

Auxins are the first type of plant hormone to be discovered. They are primarily involved in cell elongation, apical dominance, and root formation. Auxins also play a role in the plant's response to light and gravity, a phenomenon known as phototropism and gravitropism respectively.

Gibberellins

Gibberellins are a large family of plant hormones that stimulate stem elongation, germination, and flowering. They also play a role in breaking dormancy, a state of arrested plant growth.

Cytokinins

Cytokinins promote cell division and shoot formation. They also help delay senescence, the aging process in plants. Cytokinins are often used in tissue culture to induce the formation of callus, an undifferentiated mass of cells.

Abscisic Acid

Abscisic acid (ABA) is a plant hormone that regulates plant response to stress and acts primarily in plant growth, dormancy, and stomatal closure.

Ethylene

Ethylene is a gaseous plant hormone that promotes fruit ripening and opposes some of the actions of auxins and gibberellins. It also plays a role in senescence, leaf abscission, and defense against pathogens.

Function of Plant Hormones

Plant hormones function as chemical messengers, controlling the growth and development of cells and tissues. They are produced in one part of the plant and transported to other parts, where they trigger specific responses. These responses include cell division, elongation, differentiation, and death. They also mediate the plant's response to environmental stimuli, such as light, gravity, and stress.

See Also

• Plant Physiology
• Plant Growth
• Plant Development
• Plant Tissue Culture

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