Latest revision as of 14:19, 21 February 2025

Plant Hormone[edit]

Auxin, a key plant hormone.

Plant hormones, also known as phytohormones, are naturally occurring organic compounds that play crucial roles in regulating the growth, development, and responses of plants. These hormones are produced in small quantities and can have significant effects on plant physiology.

Types of Plant Hormones[edit]

Plant hormones are classified into several major groups, each with distinct functions and effects on plant growth and development.

Auxins[edit]

File:Indol-3-ylacetic acid.svg

Chemical structure of Indole-3-acetic acid, a common auxin.

Auxins are a class of plant hormones that primarily regulate cell elongation, apical dominance, and root initiation. The most common naturally occurring auxin is Indole-3-acetic acid (IAA). Auxins are involved in various plant processes, including phototropism and gravitropism.

Cytokinins[edit]

File:Zeatin.png

Chemical structure of Zeatin, a type of cytokinin.

Cytokinins are a group of hormones that promote cell division and differentiation. They are involved in processes such as shoot initiation and growth, leaf expansion, and delay of senescence. Zeatin is a well-known cytokinin found in many plants.

Gibberellins[edit]

File:Gibberellin A1.svg

Chemical structure of Gibberellin A1.

Gibberellins are a group of hormones that stimulate stem elongation, seed germination, and flowering. They are essential for breaking seed dormancy and promoting growth in various plant parts. Gibberellin A1 is one of the many gibberellins identified in plants.

Abscisic Acid[edit]

File:Abscisic acid.svg

Chemical structure of Abscisic acid.

Abscisic acid (ABA) is a plant hormone that plays a crucial role in stress responses, such as drought tolerance, and in the regulation of stomatal closure. It is also involved in seed dormancy and abscission processes.

Ethylene[edit]

File:Ethene-2D-flat.png

Chemical structure of Ethylene.

Ethylene is a gaseous plant hormone that influences fruit ripening, flower wilting, and leaf abscission. It is unique among plant hormones due to its gaseous state and is involved in the response to mechanical stress and pathogen attack.

Brassinosteroids[edit]

File:Brassinolide.png

Chemical structure of Brassinolide, a type of brassinosteroid.

Brassinosteroids are a class of polyhydroxysteroids that promote cell expansion and elongation, vascular differentiation, and stress tolerance. Brassinolide is one of the most studied brassinosteroids.

Functions of Plant Hormones[edit]

Plant hormones regulate a wide range of physiological processes, including:

Growth and Development: Hormones like auxins, cytokinins, and gibberellins are crucial for cell division, elongation, and differentiation.
Stress Responses: Abscisic acid and ethylene play significant roles in plant responses to environmental stresses such as drought, salinity, and pathogen attack.
Reproductive Development: Hormones regulate flowering, fruit development, and seed germination.
Senescence and Abscission: Ethylene and abscisic acid are involved in leaf senescence and the abscission of leaves and fruits.

Related Pages[edit]

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-'''Plant hormones''' (also known as '''phytohormones''') are chemicals that regulate plant growth. In the UK, these are termed 'plant growth substances'. Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted cells locally and, when moved to other locations, in other locations of the plant. Hormones also determine the formation of flowers, stems, leaves, the shedding of leaves, and the development and ripening of fruit. Plants, unlike animals, lack glands that produce and secrete hormones. Instead, each cell is capable of producing hormones. Plant hormones shape the plant, affecting seed growth, time of flowering, the sex of flowers, senescence of leaves, and fruits. They affect which tissues grow upward and which grow downward, leaf formation and stem growth, fruit development and ripening, plant longevity, and even plant death. Hormones are vital to plant growth, and, lacking them, plants would be mostly a mass of undifferentiated cells. So they are also known as growth factors or growth hormones.
+= Plant Hormone =
-The term '''phytohormone''' was coined by Thimann in 1948. The word 'phytohormone' is derived from Greek φυτόν ('phyton'), meaning 'plant' and hormone, meaning 'to set in motion'.
+[[File:Auxin.jpg|thumb|right|Auxin, a key plant hormone.]]
-==Types of plant hormones==
+'''Plant hormones''', also known as '''phytohormones''', are naturally occurring organic compounds that play crucial roles in regulating the growth, development, and responses of plants. These hormones are produced in small quantities and can have significant effects on plant physiology.
-Plant hormones are categorized into five main types: [[auxin]], [[cytokinin]], [[gibberellin]], [[abscisic acid]] and [[ethylene]]. Each of these hormones has a distinct role in plant growth and development.
-===Auxin===
+== Types of Plant Hormones ==
-[[Auxin]] is a plant hormone produced in the stem tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to grow larger than corresponding cells on the lighter side of the plant.
-===Cytokinin===
+Plant hormones are classified into several major groups, each with distinct functions and effects on plant growth and development.
-[[Cytokinin]]s are a class of plant growth substances that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation.
-===Gibberellin===
+=== Auxins ===
-[[Gibberellin]]s are plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence.
+[[File:Indol-3-ylacetic_acid.svg|thumb|left|Chemical structure of Indole-3-acetic acid, a common auxin.]]
+Auxins are a class of plant hormones that primarily regulate cell elongation, apical dominance, and root initiation. The most common naturally occurring auxin is [[Indole-3-acetic acid]] (IAA). Auxins are involved in various plant processes, including phototropism and gravitropism.
-===Abscisic Acid===
+=== Cytokinins ===
-[[Abscisic acid]] (ABA) is a plant hormone. ABA functions in many plant developmental processes, including seed and bud dormancy, the control of organ size, and stomatal closure.
+[[File:Zeatin.png|thumb|right|Chemical structure of Zeatin, a type of cytokinin.]]
+Cytokinins are a group of hormones that promote cell division and differentiation. They are involved in processes such as shoot initiation and growth, leaf expansion, and delay of senescence. Zeatin is a well-known cytokinin found in many plants.
-===Ethylene===
+=== Gibberellins ===
-[[Ethylene]] is a gaseous plant hormone which regulates a wide range of biological processes. It is involved in processes such as ripening of fruits, opening of flowers, shedding of leaves, and senescence of green tissues.
+[[File:Gibberellin_A1.svg|thumb|left|Chemical structure of Gibberellin A1.]]
+Gibberellins are a group of hormones that stimulate stem elongation, seed germination, and flowering. They are essential for breaking seed dormancy and promoting growth in various plant parts. Gibberellin A1 is one of the many gibberellins identified in plants.
-==See also==
+=== Abscisic Acid ===
-* [[Plant physiology]]
+[[File:Abscisic_acid.svg|thumb|right|Chemical structure of Abscisic acid.]]
-* [[Plant perception (physiology)]]
+Abscisic acid (ABA) is a plant hormone that plays a crucial role in stress responses, such as drought tolerance, and in the regulation of stomatal closure. It is also involved in seed dormancy and abscission processes.
-* [[Plant morphology]]
-==References==
+=== Ethylene ===
-<references />
+[[File:Ethene-2D-flat.png|thumb|left|Chemical structure of Ethylene.]]
+Ethylene is a gaseous plant hormone that influences fruit ripening, flower wilting, and leaf abscission. It is unique among plant hormones due to its gaseous state and is involved in the response to mechanical stress and pathogen attack.
+=== Brassinosteroids ===
+[[File:Brassinolide.png|thumb|right|Chemical structure of Brassinolide, a type of brassinosteroid.]]
+Brassinosteroids are a class of polyhydroxysteroids that promote cell expansion and elongation, vascular differentiation, and stress tolerance. Brassinolide is one of the most studied brassinosteroids.
+== Functions of Plant Hormones ==
+Plant hormones regulate a wide range of physiological processes, including:
+* '''Growth and Development''': Hormones like auxins, cytokinins, and gibberellins are crucial for cell division, elongation, and differentiation.
+* '''Stress Responses''': Abscisic acid and ethylene play significant roles in plant responses to environmental stresses such as drought, salinity, and pathogen attack.
+* '''Reproductive Development''': Hormones regulate flowering, fruit development, and seed germination.
+* '''Senescence and Abscission''': Ethylene and abscisic acid are involved in leaf senescence and the abscission of leaves and fruits.
+== Related Pages ==
+* [[Phototropism]]
+* [[Gravitropism]]
+* [[Seed dormancy]]
+* [[Apical dominance]]
+[[Category:Plant physiology]]
 [[Category:Plant hormones]]
-[[Category:Plant physiology]]
-[[Category:Botany]]
-{{stub}}

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