Name the plant hormone responsible for promotion of cell division

In plants, growth, development, and response to the environment are controlled and coordinated by a special class of chemical substances known as phytohormones. They are naturally occurring organic substances which are synthesized in minute quantities. These hormones are produced in one part of the plant body and are translocated to other parts. For example, a hormone produced in the roots is translocated to other parts where they are required. (i) Gibberellins (ii) Cytokinins (iii) Abscisic acid (iv) Auxins

Cytokinin is the plant hormone responsible for the promotion of cell division and gibberellins is the hormone responsible for cell elongation. Explanation: HORMONES are chemical compounds which help to coordinate growth, development and responses to the environment. Cytokinins (CK) are a class of plant growth substances (phyto-hormones) that promote cell division. They are the positive regulators of cell division in shoot apical meristem. Gibberellins (GAs) are plant hormones that regulate growth and influence various developmental processes, including stem elongation.

\( \newcommand\) • • • • • • • • • • Learning objectives Learning Objectives By the end of this lesson, you will be able to: • Understand the role of the five major hormone groups in plant growth and development. • Recognize that cells, tissues, and organs have unique competency to respond to specific hormones. • Connect specific hormones to plant responses and how they are used in plant propagation. How plants respond to hormones The five major groups of plant hormones — auxins, cytokinins, gibberellins, ethylene, and abscisic — acid are distinguished by their chemical structures and the response they evoke within the plant (see Table 4.1). For any cell to respond to a hormone it must be competent to perceive the chemical. Some cells simply lack the ability to “see” the hormone and do not respond to its presence. Competency to perceive a hormone depends on a cell’s physiology when the hormone is present. If the hormone is perceived, its unique chemical structure causes a chain reaction or signal transduction that involves changes in gene expression and cell morphology. These cellular responses to hormones can lead to changes we see in the plant, such as movement towards light, a transition from vegetative growth to flowering, or the closing of leaf stomata due to drought stress. The perception of the hormone occurs in cells and throughout a tissue or organ, depending on where the hormone is located, the concentration of the hormone, and the developmental state and physiol...

\( \newcommand\) • • • • • • • Growth Responses A plant’s sensory response to external stimuli relies on hormones, which are simply chemical messengers. Plant hormones affect all aspects of plant life, from flowering to fruit setting and maturation, and from phototropism to leaf fall. Potentially, every cell in a plant can produce plant hormones. The hormones can act in their cell of origin or be transported to other portions of the plant body, with many plant responses involving the synergistic or antagonistic interaction of two or more hormones. In contrast, animal hormones are produced in specific glands and transported to a distant site for action, acting alone. Plant hormones are a group of unrelated chemical substances that affect plant morphogenesis. Five major plant hormones are traditionally described: auxins, cytokinins, gibberellins, ethylene, and abscisic acid. In addition, other nutrients and environmental conditions can be characterized as growth factors. The first three plant hormones largely affect plant growth, as described below. Auxins The term auxin is derived from the Greek word auxein, which means “to grow. ” Auxins are the main hormones responsible for cell elongation in phototropism and gravitropism. They also control the differentiation of meristem into vascular tissue and promote leaf development and arrangement. While many synthetic auxins are used as herbicides, indole acetic acid (IAA) is the only naturally-occurring auxin that shows physiolog...

Auxin: • Auxin is the plant hormone responsible for the elongation of cells • The word auxin, which means "to grow," is frequently used in the fields of horticulture and agriculture. • They are typically produced in the roots and stems of plants. • The primary purpose of the cells is to elongate, although they also aid in cell division and xylem differentiation. • They also aid in preventing the early fall of flowers, fruits, and leaves.

Learning Objectives • Identify the hormones that regulate specific plant behaviors and describe their role in that behavior, including auxin, cytokinins, gibberellins, abscisic acid, ethylene, systemin, and methyl salicylate • Recognize the stimulus that provokes a specific plant behavior, including phototropism, gravitropism, germination, thigmotropism, water/water stress and pathogen/herbivory defense • Describe the pathways that regulates plant behaviors, including phototropism, gravitropism, germination, thigmotropism, water/water stress, and pathogen/herbivory defense • Interpret and predict outcomes of experiments manipulating plant signaling pathways Hormones in plants The information below was adapted from A plant’s sensory response to external stimuli relies on chemical messengers (hormones). Plant hormones affect all aspects of plant life, from flowering to fruit setting and maturation, and from phototropism to leaf fall. Just as in animals, hormones are signaling molecules which are present in very small amounts, transported throughout the plant body, and only elicit in responses in cells which have the appropriate hormone receptors. In plants, hormones travel large throughout the body via the vascular tissue (xylem and phloem) and cell-to-cell via plasmodesmata. Potentially every cell in a plant can produce plant hormones. In contrast, many animal hormones are produced only in specific glands. Plants do not have specialized hormone-producing glands. Hormones re...

Plant hormones: • Plant growth substances, phytohormones, and plant growth regulators describe plant hormones. • They are small, simple compounds with a wide range of chemical properties. • Examples - Auxins, Gibberellins, Cytokinins, Ethylene, and Abscisic acid. (i) Growth of stem - Gibberellins • Gibberellins promote stem elongation. • They are utilized to increase the length of grape stems because of their capacity to promote an increase in axis length. • Bolting (internode elongation just prior to blooming) is similarly promoted by gibberellins in beets, cabbages, and many other rosette-forming plants. (ii) Promotion of cell division - Cytokinin • Cytokinins promote cell division. • Natural cytokinins are produced in areas with rapid cell division, such as root apices, growing shoot buds, and immature fruits. (iii) Inhibition of growth - Abscisic acid (ABA) • ABA is a plant growth inhibitor. • ABA promotes the closing of stomata and increases plant tolerance to various stressors. • As a result, it's also known as the stress hormone.

Learning Objectives • Identify the hormones that regulate specific plant behaviors and describe their role in that behavior, including auxin, cytokinins, gibberellins, abscisic acid, ethylene, systemin, and methyl salicylate • Recognize the stimulus that provokes a specific plant behavior, including phototropism, gravitropism, germination, thigmotropism, water/water stress and pathogen/herbivory defense • Describe the pathways that regulates plant behaviors, including phototropism, gravitropism, germination, thigmotropism, water/water stress, and pathogen/herbivory defense • Interpret and predict outcomes of experiments manipulating plant signaling pathways Hormones in plants The information below was adapted from A plant’s sensory response to external stimuli relies on chemical messengers (hormones). Plant hormones affect all aspects of plant life, from flowering to fruit setting and maturation, and from phototropism to leaf fall. Just as in animals, hormones are signaling molecules which are present in very small amounts, transported throughout the plant body, and only elicit in responses in cells which have the appropriate hormone receptors. In plants, hormones travel large throughout the body via the vascular tissue (xylem and phloem) and cell-to-cell via plasmodesmata. Potentially every cell in a plant can produce plant hormones. In contrast, many animal hormones are produced only in specific glands. Plants do not have specialized hormone-producing glands. Hormones re...

Auxin: • Auxin is the plant hormone responsible for the elongation of cells • The word auxin, which means "to grow," is frequently used in the fields of horticulture and agriculture. • They are typically produced in the roots and stems of plants. • The primary purpose of the cells is to elongate, although they also aid in cell division and xylem differentiation. • They also aid in preventing the early fall of flowers, fruits, and leaves.

Hormones – Mighty Messengers! Hormones get things done. Think of them as chemical messengers that are made in one place in the body and deliver their message in a totally different place in the body. And just like hot sauce, a little goes a long way. Hormones are usually found in very small concentrations, but boy to they pack a punch! We know hormones cause a lot of changes in humans (ah, puberty), but did you know that plants have hormones, too? Plants miss out on all the fun of body hair, acne, and voice changes, but read on to learn about the amazing effects that hormones have on plant growth and development! The Big Five We’ll cover five major types of plant hormones: auxin, gibberellin, cytokinin, ethylene, and abscisic acid. These hormones can work together or independently to influence plant growth. AUXIN You’ve seen auxin in action. Well you haven’t seen the actual auxin molecule itself with the naked eye, but you’ve seen what it can do to a plant grown near a window. Have you ever wondered how a plant bends towards sunlight? Well, it has to do with auxin in the stem. Darwin and his son were curious about it, too. (Published in: The Power and Movement in Plants) However, they didn’t know at the time what exactly was causing plants to bend toward the light. Auxin itself wasn’t discovered until the late 1920s, and it was the first of the 5 major types of plant hormones to be studied. Auxin has lots of jobs but most importantly it stimulates growth, and if a plant do...