i have never used Cytokinin, like other orchid growers i am looking at any way to improve my plants

http://www.super-grow.biz/Products.jsp

I've never heard of it. Did you mean cytokinin?

Auxin,Cytokinin,Abscic Acids,Gibberellin,&Ethylene

The ratio of auxin to cytokinin is crucial in callus culture because it directly influences cell division and differentiation. A higher ratio of cytokinin promotes shoot formation, while a higher ratio of auxin favors root formation. Balancing these hormones is essential for generating healthy and productive callus cultures.

Cytokinin

It is plant growth regulator. it is a cytokinin. Cytokinin is involved in both local and long distance signalling; as a long distance signal CK shares the same transport systems used by the plant for moving purines and nucleosides. Cytokinins are involved in many plant processes, including cell division, shoot and root morphogenesis, chloroplast maturation, cell enlargement, auxiliary bud release and senescence. The ratio of auxin to cytokinin is crucial during cell division and the differentiation of plant tissues and auxin is known to regulate the biosynthesis of cytokinin

Cytokinin is a plant hormone that plays a vital role in cell division. It is primarily found in roots and fruits, where it regulates cellular processes such as growth and development.

For the tissue culture/callus culture of Alstonia scholaris MS media supplemented with a balanced concentrations of 2,4-D(auxin) and FAP(cytokinin) can be used.The concentrations of auxin/cytokinin are*****mg/l [(kumarsumit90@gmail.com :) ;)]

cytokinin

Cytokinin is the plant hormone that stimulates cell division. It plays a role in promoting cell growth and differentiation.

yes,indeed yes.hormones such as anxins,gibberrellins,cytokinin helps plants to grow.

Yes many plant hormones are secreted by plants internally. Such as auxin, gibbrailin, cytokinin etc.

Norman Leonard Biddington has written:

'Cytokinin involvement in seed germination and some other plant processes'

Cytokinin are made in greatest amounts in the roots. Simply put, they may be an indication that things are going well for the root and shoot growth may therefore commence. The principle roles of the root are to take in water and minerals from the soil, to anchor the plant and to store nutrients like starch that has been made by the leaves (the last in some but not all plants).

Since it's possible that salicylic acid acting as a hormone may be an indicator of an abundance of water, cytokinin may indicate that the plant is taking in more than enough minerals from the soil to just survive, so that it is OK to start growing more stems and leaves. In fact cytokinin inhibits senescence of leaves, and promotes new stem growth. Whether it needs a high level of salicylic acid also as indicator to give the green light to stem growth, is a good question...

It's also quit probable that even if the plant is taking in good amounts of water and minerals from the roots they would not make salicylic acid and cytokinin if the root were under duress for other reasons, say by infestation, flooding or dislodging. In other words any condition that plant is in where it might be good to wait to start growth until a better situation is achieved. It's possible cytokinin is still made under these circumstances but the minerals are instead store for a better day.

One last possibility is cytokinin alone indicates root prospering just as perhaps auxin alone indicates stem prospering. The reason for saying this is that cloning a single isolated plant cell into a full new plant, seems to require only cytokinin and auxin, not the additional salicylic and jasmonic acid (jasmonate is proposed in this present author's scheme as a sugar indicator with Auxin relegated to a role as a carbon dioxide and oxygen uptake indicator).

Mind you most scientist woulds consider this entire answer highly speculative.

Ethylene and cytokinin are both plant hormones that can interact with each other to regulate various plant processes, but they do not directly depend on each other for their functions. Ethylene is involved in fruit ripening, senescence, and stress responses, while cytokinins are involved in cell division, shoot growth, and root development. Their relationship can be synergistic or antagonistic depending on the specific pathway or process being regulated.

Cytokinins are plant hormones that promote cell division and growth. They also influence apical dominance, root growth, and leaf senescence. Additionally, cytokinins play a role in regulating plant responses to environmental stresses.

Cytokinins have been found to accelerate cell division rates by encoding a D-type cyclin that is believed to be vital to cell cycle transition. More research is still being conducted in this area, however.

Promoting undifferentiated cell proliferation in the central zone of shoot apical meristem. The continuous cell multiplication will become the input for differentiated tissues (stem, leaf, branch and inflorescence) development

The Richmond Lang effect is produced by the increased firing rate of muscle spindles that occurs when a muscle is subjected to a sudden stretch. This reflex response helps to protect the muscle from potential injury by quickly contracting in response to stretching.

Morphogenesis in plants results from the coordination of cell division, elongation, and differentiation. Hormones such as auxin and cytokinin play a key role in regulating these processes, along with environmental factors like light and temperature. The unique cell walls of plant cells also contribute to the overall shape and structure of the plant.

Plant hormones can stimulate the development of fruit without seeds through a process called parthenocarpy. By manipulating the balance of hormones such as auxin, cytokinin, and gibberellins, seedless fruits can be produced. This can be achieved naturally or through genetic modification techniques.

Due to leaf senescence. In autumn the leaves stop being the sink for phloem transport so the nutrient supply dwindles so the leaves age and turn brown (since there are no nutrients to carry on producing more chlorophyll etc.).

Senescence occurs due to reduced levels of cytokinin (plant "hormone") production.

Coconut milk contains a growth factor known as cytokinins, which are plant hormones that have been associated with promoting cell division and overall plant growth. They have also been studied for potential health benefits in humans, such as anti-aging properties and antioxidant effects.

Inteferons are proteins produced and released by lymphocytes .The presence of pathogens like virus,bacteria,parasites or tumor cells near any infected cell warns the neighboring cell to release inteferons that inhibit the protein synthesis of both the host cell and pathogen cell .The cytokinin inteferon prevents the reduplication of any pathogen cell.

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern ---OKI-I-. That is, nine letter words with 4th letter O and 5th letter K and 6th letter I and 8th letter I. In alphabetical order, they are:

cytokinin

monokinis

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern --TOKI---. That is, nine letter words with 3rd letter T and 4th letter O and 5th letter K and 6th letter I. In alphabetical order, they are:

cytokines

cytokinin

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 11 words with the pattern C---K-N--. That is, nine letter words with 1st letter C and 5th letter K and 7th letter N. In alphabetical order, they are:

caulkings

chickened

chunkings

clankings

cleckings

clickings

clockings

crackings

croakings

cytokines

cytokinin

The 4 hormones commonly used in horticulture are auxins, cytokinins, gibberellins, and abscisic acid. These hormones play key roles in plant growth and development, including cell division, shoot elongation, fruit development, and stress responses. By manipulating the levels of these hormones, horticulturists can control various aspects of plant growth and physiology.

Natural plant regulators/ stimulant are made from plant extracts, such as those produced from seaweed (kelp) and Cassava (amongst others).

These formulations contain natural growth regulators such as auxins and cytokinin, they also contain fairly high concentrations of micro-elements.

These elements stimulate growth in the plant, the increased growth then enables the plant to process and absorb more Nitrogen (as well as other elements), resulting in higher yields and fruit production.

The regulator normally provides the stimulus for growth, yield is ultimately dependant on what fertilisers are then applied to support the stimulated growth, or what nutrients the soil contains.

Cytokinins promote cell division and regulate gene expression in leaves, which delays the aging process of the tissue. They also inhibit the breakdown of chlorophyll, prolonging the green color of leaves and maintaining photosynthetic activity. Additionally, cytokinins help to maintain the balance of hormones in the plant that regulate senescence.

You can isolate a plant cell by carefully removing a small section of plant tissue, such as a leaf or stem, and then breaking down the cell wall using enzymes. This process releases the individual plant cells which can then be collected and studied under a microscope.

Some of the main hormones naturally present in plants include auxins, cytokinins, gibberellins, abscisic acid, and ethylene. These hormones play key roles in regulating various physiological processes in plants such as growth, development, and responses to environmental stimuli.

Direct morphogenesis in plant tissue culture involves the formation of shoots or roots directly from explants without the need for an intervening callus phase, while indirect morphogenesis involves the formation of callus tissue first, followed by the differentiation of shoots or roots from this callus. Direct morphogenesis is usually faster and more efficient than indirect morphogenesis, but the choice between these methods depends on the plant species and tissue type being cultured.

cytochalasin

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Plant hormones are chemical messengers that regulate growth, development, and responses to the environment in plants. They control processes such as seed germination, root and shoot growth, flowering, and fruit ripening. Some common plant hormones include auxins, cytokinins, gibberellins, abscisic acid, and ethylene.

In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also beaerial (growing above the ground) or aerating (growing up above the ground or especially above water). Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is better to define root as a part of a plant body that bears no leaves, and therefore also lacks nodes. There are also important internal structural differences between stems and roots.

The first root that comes from a plant is called theradicle. The three major functions of roots are 1) absorption of water and inorganic nutrients, 2) anchoring of the plant body to the ground and 3) storage of food and nutrients. In response to the concentration of nutrients, roots also synthesise cytokinin, which acts as a signal as to how fast the shoots can grow. Roots often function in storage of food and nutrients. The roots of most vascular plant species enter into symbiosis with certain fungi to formmycorrhizas, and a large range of other organisms including bacteria also closely associate with roots. The parts of a root are the xylem, the epidermis, the cortex, the root cap, the root hairs, the phloem, and the cambium.

Coconut water can serve as a source of nutrients and growth factors in tissue culture medium, supporting the growth and development of plant cells and tissues. Its natural composition of sugars, vitamins, and minerals can help enhance cell proliferation and organogenesis in vitro. Additionally, the cytokinins present in coconut water can stimulate shoot formation and overall growth in plant tissue cultures.

Cell division is facilitated by a series of processes, including duplication of genetic material, separation of duplicated chromosomes, and division of cytoplasm to create two daughter cells. Key players in these processes are proteins such as cyclins and cyclin-dependent kinases that regulate the cell cycle progression and formation of the mitotic spindle that helps to segregate chromosomes during cell division. Additionally, molecular signaling pathways and checkpoints ensure proper timing and accuracy of cell division.

The function of root hairs is to increase surface area for nutrient absorption which is vital for plant survival.

1) absorption of water and inorganic nutrients

2) anchoring of the plant body to the ground

3) function in storage of food and nutrients

4) in response to the concentration of nutrients, roots also synthesise cytokinin, which acts as a signal as to how fast the shoots can grow.

Definition: Shrinkage or contraction of the protoplasm away from the wall of a living plant or bacterial cell, caused by loss of water through osmosis. Example: If a plant cell is placed in a more concentrated salt (http://www.answers.com/topic/hypertonic) solution, it loses water and hence http://www.answers.com/topic/turgor-pressure-1 pressure, making it http://www.answers.com/topic/flaccid-2. Plants with cells in this condition wilt. Further water loss causes plasmolysis.

The root system of a flowering plant begins its development from the hypocotyl of the embryo of the seed which gives rise to the primary root. Roots generally grow downwards into the soil (positively geotropic) and upwards (negatively geotropic). Roots do not bear leaves and therefore no nodes are present.Two kinds of root systems can be distinguished in flowering plants: tap root systems and adventitious root systems. Usually dicotyledons posses tap root systems and monocotyledons adventitious root systems.

Tap Root System: The primary root grows vertically down into the soil in the tap root system. Later lateral or secondary roots grow from this at an acute angle outwards and downwards, and from these other branches may arise. The main or primary root is known as the tap root; together with its many branch roots it forms a tap root system e.g. the bean.

Adventitious Root System: The primary root usually dies at an early stage and is replaced by numerous roots that develop from the stem. These roots, which develop from the stem, are equal in size. They are known as a adventitious roots, which give rise to branch or lateral roots and form an adventitious root system, e.g. the mealie.

Functions of the Root

Roots anchor the plant in the soil.

Roots absorb water and mineral salts from the soil.

Roots may store food.

Roots form a passage way for water and dissolved substances from the root into the stem and also for foods from the stem down into the root.

Root of a Dicotyledonous Plant: External Features

If we study the root tip of a flower plant under a dissecting microscope or with a hand lens, the following regions can be distinguished:

The Root Cap

The tip of the root is covered by a cap that is shaped like a thimble. The outer cells of the root cap are continuously being worn away and new cells are added to the inner portion. As these cells disintegrate they form a strong protective cover.

Function

The root cap covers and protects the delicate growing tip from injury and damage as the root pushes its way through the soil.

The Meristematic Region or Growing Point

This region occurs immediately behind the root cap. The Meristematic region consists of meristematic tissue and is protected by the root cap. The cells are very active and divide rapidly to form new cells which differentiate later to form more specialized root tissues. The cells of this region also replace the cells rubbed-off from the root cap and provide additional cells for the next region.

Function

This is the region where the cells divide and where additional cells are provided for the zone of elongation.

The Region of Elongation

The cells formed in the meristematic region undergo rapid growth in length. This causes the root to elongate and penetrate deeper into the soil in search for water and mineral salts. The meristematic and elongation zones are also referred to as the region of growth.

Function

In this region the cells undergo rapid enlargement,i.e. the cells undergo rapid growth in length.

The Root-hair Region

The root hair region occurs a short distance above the region of elongation. Here a large number of fine, hair-like outgrowths are formed. The root hairs arise from the epidermal tissue of the root and are called root hairs. The root hairs are short and short-lived and develop on the primary and secondary roots. A root-hair consists of the following parts: a thin cell wall, a thin lining of cytoplasm which contains the nucleus and a comparatively large vacuole containing cell sap.

Function

The main function of the root hairs is to increase the area of absorption of the root.

The Mature Region

The mature region is situated above the root hair region. Here the root becomes thicker and secondary or lateral roots are developed. The secondary roots in turn rebranch to form tertiary roots. Each lateral branch has its own cap, root hairs, meristematic, elongation and mature regions. The roots in this region are covered by a protective cork layer .

Functions

In this region the cells undergo differentiation into specialized cells,(e.g. xylem and phloem).

It also serves to anchor the plant.

~

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. But, this is not always the case, since a root can also be aerial (that is, growing above the ground) or aerating (that is, growing up above the ground or especially above water). On the other hand, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is better to define root as a part of a plant body that bears no leaves, and therefore also lacks nodes. There are also important internal structural differences between stems and roots. The two major functions of roots are 1.) absorption of water and inorganic nutrients and 2.) anchoring the plant body to the ground. Roots also function in cytokinin synthesis, which supplies some of the shoot's needs. They often function in storage of food. The roots of most vascular plant species enter into symbiosis with certain fungi to form mycorrhizas, and a large range of other organisms including bacteria also closely associate with roots.

At the tip of every growing root is a conical covering of tissue called the root cap. It usually is not visible to the naked eye. It consists of undifferentiated soft tissue (parenchyma) with unthickened walls covering the apical meristem. The root cap provides mechanical protection to the meristem cells as the root advances through the soil. Its cells are worn away, however, they are quickly replaced by new cells generated by cell division within the meristem. The root cap is also involved in the production of mucigel, a sticky mucilage that coats the new formed cells. These cells contain statoliths, starch grains that move in response to gravity and thus control root orientation.

Stem

******

A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence (flowers), cones or other stems etc. The internodes act as spaces that distance one node from another. The term shoots is often confused with stems; shoots generally refer to new fresh plant growth and does include stems but also to other structures like leaves or flowers. The other main structural axis of plants is the root. In most plants stems are located above the soil surface but some plants have underground stems.

Stems have four main functions which are:[1]

Support for and the elevation of leaves, flowers and fruits. The stems keep the leaves in the light and provide a place for the plant to keep its flowers and fruits.

Transport of fluids between the roots and the shoots in the xylem and phloem.

Storage of nutrients.

The production of new living tissue. The normal life span of plant cells is one to three years. Stems have cells called meristems that annually generate new living tissue.

Structure

Stem usually consist of three tissues, dermal tissue, ground tissue and vascular tissue. The dermal tissue covers the outer surface of the stem and usually functions to waterproof, protect and control gas exchange. The ground tissue usually consists mainly of parenchyma cells and fills in around the vascular tissue. It sometimes functions in photosynthesis. Vascular tissue provides long distance transport and structural support. Most or all ground tissue may be lost in woody stems. The dermal tissue of aquatic plants stems may lack the waterproofing found in aerial stems. The arrangement of the vascular tissues varies widely among plant species.

Leaves

********

A structurally complete leaf of an angiosperm consists of a petiole (leaf stem), a lamina (leaf blade), and stipules (small processes located to either side of the base of the petiole). The petiole attaches to the stem at a point called the "leaf axil". Not every species produces leaves with all of the aforementioned structural components. In some species, paired stipules are not obvious or are absent altogether. A petiole may be absent, or the blade may not be laminar (flattened). The tremendous variety shown in leaf structure (anatomy) from species to species is presented in detail below under Leaf morphology. After a period of time (i.e. seasonally, during the autumn), deciduous trees shed their leaves. These leaves then decompose into the soil.

A leaf is considered a plant organ and typically consists of the following tissues:

An epidermis that covers the upper and lower surfaces

An interior chlorenchyma called the mesophyll

An arrangement of veins (the vascular tissue).

In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat (laminar) and thin, to expose the cells containing chloroplast (chlorenchyma tissue, a type of parenchyma) to light over a broad area, and to allow light to penetrate fully into the tissues. Leaves are also the sites in most plants where transpiration and guttation take place. Leaves can store food and water, and are modified in some plants for other purposes. The comparable structures of ferns are correctly referred to as fronds. Furthermore, leaves are prominent in the human diet as leaf vegetables.

Agrobacterium tumefaciens, a soil rhizosphere bacterium, can attach to plant cells and infect them with a callus-inducing Ti plasmid by horizontal gene transfer, causing a callus infection called crown gall disease. Schell and Van Montagu (1977) hypothesised that the Ti plasmid could be a natural vector for introducing the Nif gene responsible for nitrogen fixation in the root nodules of legumes and other plant species. Today, genetic modification of the Ti plasmid is one of the main techniques for introduction of transgenes to plants and the creation of genetically modified crops. Epigenetics is the study of heritable changes in gene function that cannot be explained by changes in the underlying DNA sequence but cause the organism's genes to behave (or "express themselves") differently. One example of epigenetic change is the marking of the genes by DNA methylation which determines whether they will be expressed or not. Gene expression can also be controlled by repressor proteins that attach to silencer regions of the DNA and prevent that region of the DNA code from being expressed. Epigenetic marks may be added or removed from the DNA during programmed stages of development of the plant, and are responsible, for example, for the differences between anthers, petals and normal leaves, despite the fact that they all have the same underlying genetic code. Epigenetic changes may be temporary or may remain through successive cell divisions for the remainder of the cell's life. Some epigenetic changes have been shown to be heritable, while others are reset in the germ cells. Epigenetic changes in eukaryotic biology serve to regulate the process of cellular differentiation. During morphogenesis, totipotent stem cells become the various pluripotent cell lines of the embryo, which in turn become fully differentiated cells. A single fertilised egg cell, the zygote, gives rise to the many different plant cell types including parenchyma, xylem vessel elements, phloem sieve tubes, guard cells of the epidermis, etc. as it continues to divide. The process results from the epigenetic activation of some genes and inhibition of others.Unlike animals, many plant cells, particularly those of the parenchyma, do not terminally differentiate, remaining totipotent with the ability to give rise to a new individual plant. Exceptions include highly lignified cells, the sclerenchyma and xylem which are dead at maturity, and the phloem sieve tubes which lack nuclei. While plants use many of the same epigenetic mechanisms as animals, such as chromatin remodelling, an alternative hypothesis is that plants set their gene expression patterns using positional information from the environment and surrounding cells to determine their developmental fate.Epigenetic changes can lead to paramutations, which do not follow the Mendelian heritage rules. These epigenetic marks are carried from one generation to the next, with one allele inducing a change on the other. The chloroplasts of plants have a number of biochemical, structural and genetic similarities to cyanobacteria, (commonly but incorrectly known as "blue-green algae") and are thought to be derived from an ancient endosymbiotic relationship between an ancestral eukaryotic cell and a cyanobacterial resident.The algae are a polyphyletic group and are placed in various divisions, some more closely related to plants than others. There are many differences between them in features such as cell wall composition, biochemistry, pigmentation, chloroplast structure and nutrient reserves. The algal division Charophyta, sister to the green algal division Chlorophyta, is considered to contain the ancestor of true plants. The Charophyte class Charophyceae and the land plant sub-kingdom Embryophyta together form the monophyletic group or clade Streptophytina.Nonvascular land plants are embryophytes that lack the vascular tissues xylem and phloem. They include mosses, liverworts and hornworts. Pteridophytic vascular plants with true xylem and phloem that reproduced by spores germinating into free-living gametophytes evolved during the Silurian period and diversified into several lineages during the late Silurian and early Devonian. Representatives of the lycopods have survived to the present day. By the end of the Devonian period, several groups, including the lycopods, sphenophylls and progymnosperms, had independently evolved "megaspory" – their spores were of two distinct sizes, larger megaspores and smaller microspores. Their reduced gametophytes developed from megaspores retained within the spore-producing organs (megasporangia) of the sporophyte, a condition known as endospory. Seeds consist of an endosporic megasporangium surrounded by one or two sheathing layers (integuments). The young sporophyte develops within the seed, which on germination splits to release it. The earliest known seed plants date from the latest Devonian Famennian stage. Following the evolution of the seed habit, seed plants diversified, giving rise to a number of now-extinct groups, including seed ferns, as well as the modern gymnosperms and angiosperms. Gymnosperms produce "naked seeds" not fully enclosed in an ovary; modern representatives include conifers, cycads, Ginkgo, and Gnetales. Angiosperms produce seeds enclosed in a structure such as a carpel or an ovary. Ongoing research on the molecular phylogenetics of living plants appears to show that the angiosperms are a sister clade to the gymnosperms. Plant physiology encompasses all the internal chemical and physical activities of plants associated with life. Chemicals obtained from the air, soil and water form the basis of all plant metabolism. The energy of sunlight, captured by oxygenic photosynthesis and released by cellular respiration, is the basis of almost all life. Photoautotrophs, including all green plants, algae and cyanobacteria gather energy directly from sunlight by photosynthesis. Heterotrophs including all animals, all fungi, all completely parasitic plants, and non-photosynthetic bacteria take in organic molecules produced by photoautotrophs and respire them or use them in the construction of cells and tissues. Respiration is the oxidation of carbon compounds by breaking them down into simpler structures to release the energy they contain, essentially the opposite of photosynthesis.Molecules are moved within plants by transport processes that operate at a variety of spatial scales. Subcellular transport of ions, electrons and molecules such as water and enzymes occurs across cell membranes. Minerals and water are transported from roots to other parts of the plant in the transpiration stream. Diffusion, osmosis, and active transport and mass flow are all different ways transport can occur. Examples of elements that plants need to transport are nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. In vascular plants, these elements are extracted from the soil as soluble ions by the roots and transported throughout the plant in the xylem. Most of the elements required for plant nutrition come from the chemical breakdown of soil minerals. Sucrose produced by photosynthesis is transported from the leaves to other parts of the plant in the phloem and plant hormones are transported by a variety of processes. Plants are not passive, but respond to external signals such as light, touch, and injury by moving or growing towards or away from the stimulus, as appropriate. Tangible evidence of touch sensitivity is the almost instantaneous collapse of leaflets of Mimosa pudica, the insect traps of Venus flytrap and bladderworts, and the pollinia of orchids.The hypothesis that plant growth and development is coordinated by plant hormones or plant growth regulators first emerged in the late 19th century. Darwin experimented on the movements of plant shoots and roots towards light and gravity, and concluded "It is hardly an exaggeration to say that the tip of the radicle . . acts like the brain of one of the lower animals . . directing the several movements". About the same time, the role of auxins (from the Greek auxein, to grow) in control of plant growth was first outlined by the Dutch scientist Frits Went. The first known auxin, indole-3-acetic acid (IAA), which promotes cell growth, was only isolated from plants about 50 years later. This compound mediates the tropic responses of shoots and roots towards light and gravity. The finding in 1939 that plant callus could be maintained in culture containing IAA, followed by the observation in 1947 that it could be induced to form roots and shoots by controlling the concentration of growth hormones were key steps in the development of plant biotechnology and genetic modification. Cytokinins are a class of plant hormones named for their control of cell division (especially cytokinesis). The natural cytokinin zeatin was discovered in corn, Zea mays, and is a derivative of the purine adenine. Zeatin is produced in roots and transported to shoots in the xylem where it promotes cell division, bud development, and the greening of chloroplasts. The gibberelins, such as Gibberelic acid are diterpenes synthesised from acetyl CoA via the mevalonate pathway. They are involved in the promotion of germination and dormancy-breaking in seeds, in regulation of plant height by controlling stem elongation and the control of flowering. Abscisic acid (ABA) occurs in all land plants except liverworts, and is synthesised from carotenoids in the chloroplasts and other plastids. It inhibits cell division, promotes seed maturation, and dormancy, and promotes stomatal closure. It was so named because it was originally thought to control abscission. Ethylene is a gaseous hormone that is produced in all higher plant tissues from methionine. It is now known to be the hormone that stimulates or regulates fruit ripening and abscission, and it, or the synthetic growth regulator ethephon which is rapidly metabolised to produce ethylene, are used on industrial scale to promote ripening of cotton, pineapples and other climacteric crops. Another class of phytohormones is the jasmonates, first isolated from the oil of Jasminum grandiflorum which regulates wound responses in plants by unblocking the expression of genes required in the systemic acquired resistance response to pathogen attack.In addition to being the primary energy source for plants, light functions as a signalling device, providing information to the plant, such as how much sunlight the plant receives each day. This can result in adaptive changes in a process known as photomorphogenesis. Phytochromes are the photoreceptors in a plant that are sensitive to light. Plant anatomy is the study of the structure of plant cells and tissues, whereas plant morphology is the study of their external form. All plants are multicellular eukaryotes, their DNA stored in nuclei. The characteristic features of plant cells that distinguish them from those of animals and fungi include a primary cell wall composed of the polysaccharides cellulose, hemicellulose and pectin, larger vacuoles than in animal cells and the presence of plastids with unique photosynthetic and biosynthetic functions as in the chloroplasts. Other plastids contain storage products such as starch (amyloplasts) or lipids (elaioplasts). Uniquely, streptophyte cells and those of the green algal order Trentepohliales divide by construction of a phragmoplast as a template for building a cell plate late in cell division. The bodies of vascular plants including clubmosses, ferns and seed plants (gymnosperms and angiosperms) generally have aerial and subterranean subsystems. The shoots consist of stems bearing green photosynthesising leaves and reproductive structures

Gottlieb Haberlandt is credited as the "father of tissue culture" for his pioneering work in 1902 on the concept of plant cell culture and regeneration. His research laid the foundation for the development of modern techniques in tissue culture.