write the types of plant hormones with function and location and work
Answers
Answer:
Explanation:
Plant hormones (also known as phytohormones) are signal molecules produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and through to reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones.[1][2] The term 'phytohormone' was coined by Went and Thimann and used in the title of their book in 1937.[3]
Phytohormones are found across the plant kingdom, and even in algae, where they have similar functions to those seen in higher plants.[4] Some phytohormones also occur in microorganisms, such as unicellular fungi and bacteria, however in these cases they do not play a hormonal role and can better be regarded as secondary metabolites.[5]
Abscisic acid
Abscisic acid
Abscisic acid (also called ABA) is one of the most important plant growth inhibitor. It was discovered and researched under two different names before its chemical properties were fully known, it was called dormin and abscicin II. Once it was determined that the two compounds are the same, it was named abscisic acid. The name "abscisic acid" was given because it was found in high concentrations in newly abscissed or freshly fallen leaves.
Auxins
The auxin, indole-3-acetic acid
Auxins are compounds that positively influence cell enlargement, bud formation and root initiation. They also promote the production of other hormones and in conjunction with cytokinins, they control the growth of stems, roots, and fruits, and convert stems into flowers.[16] Auxins were the first class of growth regulators discovered.[17] They affect cell elongation by altering cell wall plasticity. They stimulate cambium, a subtype of meristem cells, to divide and in stems cause secondary xylem to differentiate. Auxins act to inhibit the growth of buds lower down the stems (apical dominance), and also to promote lateral and adventitious root development and growth.
Brassinosteroids
Brassinolide, a major brassinosteroid
Brassinosteroids are a class of polyhydroxysteroids, the only example of steroid based hormones in plants. Brassinosteroids control cell elongation and division, gravitropism, resistance to stress, and xylem differentiation. They inhibit root growth and leaf abscission. Brassinolide was the first identified brassinosteroid and was isolated from extracts of rapeseed (Brassica napus) pollen in 1979.[