query: which meristematic tissue is found in root and shoot apex

pos: Meristem cells and together produces most of the cells in an adult root. At its apex, the root meristem is covered by the root cap, which protects and guides its growth trajectory. Cells are continuously sloughed off the outer surface of the root cap. The QC cells are characterized by their low mitotic activity. Evidence suggests that the QC maintains the surrounding stem cells by preventing their differentiation, via signal(s) that are yet to be discovered. This allows a constant supply of new cells in the meristem required for continuous root growth. Recent findings indicate that QC can also act as

pos: Plant tissue culture are the meristematic ends of the plants like the stem tip, axillary bud tip and root tip. These tissues have high rates of cell division and either concentrate or produce required growth regulating substances including auxins and cytokinins. Shoot regeneration efficiency in tissue culture is usually a quantitative trait that often varies between plant species and within a plant species among subspecies, varieties, cultivars, or ecotypes. Therefore, tissue culture regeneration can become complicated especially when many regeneration procedures have to be developed for different genotypes within the same species. The three common pathways of plant tissue culture regeneration are propagation

pos: Epigenetics of plant growth and development for FWA. Loss of methylation in direct repeats in the 5' region of the gene results in expression of FWA and subsequent prevention of proper flowering. The gene is normally silenced by methylation of DNA in tissues not related to flowering (Soppe et al. 2000). Meristematic tissues contain cells that continue to grow and differentiate throughout the plant's lifetime. Shoot apical meristem gives rise to flowers and leaves while root apical meristem grows into roots. These components are crucial to general plant growth and are the harbingers of development. Meristematic tissue apparently contains characteristic epigenetic modifications. For example, the boundary

pos: Meristem undifferentiated (indeterminate) meristems in a plant. These differentiate into three kinds of primary meristems. The primary meristems in turn produce the two secondary meristem types. These secondary meristems are also known as lateral meristems because they are involved in lateral growth. There are two types of apical meristem tissue: shoot apical meristem (SAM), which gives rise to organs like the leaves and flowers, and root apical meristem (RAM), which provides the meristematic cells for future root growth. SAM and RAM cells divide rapidly and are considered indeterminate, in that they do not possess any defined end status. In that sense,

pos: Plant embryogenesis naturally as a result of single, or double fertilzation, of the ovule, giving rise to two distinct structures: the plant embryo and the endosperm which go on to develop into a seed. The zygote goes through various cellular differentiations and divisions in order to produce a mature embryo. These morphogenic events form the basic cellular pattern for the development of the shoot-root body and the primary tissue layers; it also programs the regions of meristematic tissue formation. The following morphogenic events are only particular to eudicots, and not monocots. Following fertilization, the zygote and endosperm are present within the ovule,

pos: CLE peptide This suggests that these two types of peptides work together to regulate the growth of the plant. The specicific peptides are: A-type peptides B-type peptides Meristematic cells give rise to various organs of the plant and keep the plant growing.There are two types of meristematic tissues 1) Apical Meristem 2) Lateral Meristem. The Apical Meristem is of two types; the shoot apical meristem (SAM) gives rise to organs like the leaves and flowers, while the root apical meristem (RAM) provides the meristematic cells for the future root growth. SAM and RAM cells divide rapidly and are considered indeterminate, in that

pos: Vegetative reproduction are easier to propagate vegetatively. Although most plants normally reproduce sexually, many can reproduce vegetatively, or can be induced to do so via hormonal treatments. This is because meristematic cells capable of cellular differentiation are present in many plant tissues. Vegetative propagation is usually considered a cloning method. However, root cuttings of thornless blackberries will revert to thorny type because the adventitious shoot develops from a cell that is genetically thorny. Thornless blackberry is a chimera, with the epidermal layers genetically thornless but the tissue beneath it genetically thorny. Similarly, leaf cutting propagation of certain chimeral variegated plants like the

pos: Meristem apical meristems are not readily cloned, however. This cloning is called asexual reproduction or vegetative reproduction and is widely practiced in horticulture to mass-produce plants of a desirable genotype. This process is also known as mericloning. Propagating through cuttings is another form of vegetative propagation that initiates root or shoot production from secondary meristematic cambial cells. This explains why basal 'wounding' of shoot-borne cuttings often aids root formation. Meristems may also be induced in the roots of legumes such as soybean, "Lotus japonicus", pea, and "Medicago truncatula" after infection with soil bacteria commonly called Rhizobium. Cells of the inner or

pos: Quiescent centre Clowes regarded the cytogenerative centre as a universal feature of roots because he used the term also with respect to the structure and function of the root meristem of conifers. Quiescent centre The Quiescent Centre is a group of cells, up to 1,000 in number, in the form of a hemisphere, with the flat face toward the root tip. It is a region in the apical meristem of a root where cell division proceeds very slowly or not at all, but the cells are capable of resuming meristematic activity should tissue surrounding them be damaged. Cells of root apical meristems

pos: Human tooth can attach to the tooth for stability. At the cement to enamel junction, the cementum is acellular due to its lack of cellular components, and this acellular type covers at least ⅔ of the root. The more permeable form of cementum, cellular cementum, covers about ⅓ of the root apex. The dental pulp is the central part of the tooth filled with soft connective tissue. This tissue contains blood vessels and nerves that enter the tooth from a hole at the apex of the root. Along the border between the dentin and the pulp are odontoblasts, which initiate the formation

pos: Quiescent centre Quiescent centre The Quiescent Centre is a group of cells, up to 1,000 in number, in the form of a hemisphere, with the flat face toward the root tip. It is a region in the apical meristem of a root where cell division proceeds very slowly or not at all, but the cells are capable of resuming meristematic activity should tissue surrounding them be damaged. Cells of root apical meristems do not all divide at the same rate. Determinations of relative rates of DNA synthesis show that primary roots of Zea, Vicia and Allium have quiescent centres to the meristems,

pos: Epigenetics of plant growth and development between the proximal meristem and elongation zone showed elevated H4K5ac along with a high level of 5mC in barley. Root meristematic tissues have been found to contain patterns for histone H4 lysine 5 acetylation, histone H3 lysine 4 and 9 di methylation and DNA methylation as 5-methyl cytosine. So far, only a casual correlation between epigenetic marks and tissue types has been established and further study is required to understand the exact involvement of the marks (Braszewska et al. 2013). Heterosis is defined as any advantages seen in hybrids. The effects of heterosis seem to follow a rather simple epigenetic

pos: Developmental biology roots grow from root meristems located at the tip of the root, and new stems and leaves grow from shoot meristems located at the tip of the shoot. Branching occurs when small clumps of cells left behind by the meristem, and which have not yet undergone cellular differentiation to form a specialized tissue, begin to grow as the tip of a new root or shoot. Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root

pos: Plant morphology shoot meristems located at the tip of the shoot. Branching occurs when small clumps of cells left behind by the meristem, and which have not yet undergone cellular differentiation to form a specialized tissue, begin to grow as the tip of a new root or shoot. Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. In addition to growth by cell division, a plant may

pos: Plant development clumps of cells left behind by the meristem, and which have not yet undergone cellular differentiation to form a specialized tissue, begin to grow as the tip of a new root or shoot. Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells

pos: Hydnora triceps of the body mirrors that of a dicotyledonous plant. There is a root-cap-like structure on the primary growth tip. Covering the entire body is a thick corky periderm, which seems to act as protection as it grows through the soil. Along the ridges of the either pentamerous or hexamerous body, are bumps of meristematic tissue. These bundles can become corky, or differentiate into flower buds, haustoria or lateral branches. The flower buds are fleshy, triangular in shape and appear white-yellowish. The flower itself is tubular with three perianth lobes that are fused together to form a cap-like structure. There are

pos: Phytomer Phytomer Phytomers are functional units of a plant, continually produced by root and shoot meristems throughout a plant's vegetative life-cycle. The phytomer unit originates at the shoot (or root) apex, and a typical phytomer consists of a node to which a leaf is attached, a subtending internode, and an axillary bud at the base of the leaf. Each component of a phytomer can continue to differentiate and grow. Increases in a phytomer can be measured using the rate of phyllochron (rate of appearance of leaves on a shoot). Related to the phyllochron is the plastochron, which is the rate of

pos: Electronic apex locator Electronic apex locator An electronic apex locator is an electronic device used in endodontics determine the position of the apical constriction and thus determine the length of the root canal space. The apex of the root has a specific resistance to electrical current, and this is measured using a pair of electrodes typically hooked into the lip and attached to an endodontic file. The electronic principle is relatively simple and is based on electrical resistance; when a circuit is complete (tissue is contacted by the tip of the file), resistance decreases markedly and current suddenly begins to flow. Various devices

pos: Plant stem cell on earth, including Bristlecone Pines in California, U.S. (4,842 years old), and the Giant Sequoia in mountainous regions of California, U.S. (87 meters in height and 2,000 tons in weight). This is possible because they have a modular body plan that enables them to survive substantial damage by initiating continuous and repetitive formation of new structures and organs such as leaves and flowers. Plant stem cells are also characterized by their location in specialized structures called meristematic tissues, which are located in root apical meristem (RAM), shoot apical meristem (SAM), and vascular system ((pro)cambium or vascular meristem.) Traditionally, plant stem

pos: Apical foramen In immature teeth the root is not fully formed leading to an open apex. This is also seen in some pathological teeth. Apical foramen In anatomy the apical foramen is the opening at the apex of the root of a tooth, through which the nerve and blood vessels that supply the dental pulp pass. Thus it represents the junction of the pulp and the periodontal tissue. The average size of the orifice is 0.3 to 0.4 mm in diameter. There can be two or more foramina separated by a portion of dentin and cementum or by cementum only. If more

pos: Regenerative endodontics inserted in the pulp chamber. These include stem cell therapy, growth factors, morphogens, tissue scaffolds and biologically active delivery systems. Closely related to the field of regenerative endodontics, are the clinical procedures apexification and apexogenesis. When the dental pulp of a developing adult tooth dies, root formation is halted leaving an open tooth apex. Attempting to complete root canal on a tooth with an open apex is technically difficult and the long-term prognosis for the tooth is poor. Apexogenesis, (which can be used when the pulp is injured but not necrotic) leaves the apical one-third of the dental pulp in

pos: Bryophyllum Bryophyllum Bryophyllum (from the Greek "bryon/bryein" = sprout, "phyllon" = leaf) is a plant genus of the Crassulaceae family that has sometimes been included within the genus "Kalanchoe". There are about forty species in the group, native originally of South Africa, Madagascar, and Asia. The group is notable for vegetatively growing small plantlets on the fringes of the leaves; these eventually drop off and root. These plantlets arise from mitosis of meristematic-type tissue in notches in the leaves. Nowadays, bryophyllums are naturalised in many parts of the tropics, and deliberately cultivated for their attractiveness or for their interesting reproduction. Several

pos: Stele (biology) Stele (biology) In a vascular plant, the stele is the central part of the root or stem containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue (pith) and a pericycle, which, if present, defines the outermost boundary of the stele. Outside the stele lies the endodermis, which is the innermost cell layer of the cortex. The concept of the stele was developed in the late 19th century by French botanists P. E. L. van Tieghem and H. Doultion as a model for understanding the relationship between the shoot and root, and for discussing

pos: Drought rhizogenesis Drought rhizogenesis Drought rhizogenesis is an adaptive root response to drought stress. New emerging roots are short, swollen, and hairless, capable of retaining turgor pressure and resistant to prolonged desiccation. Upon rewatering, they are capable of quickly forming an absorbing root surface and hair growth. This rhizogenesis has been called a drought tolerance strategy for after-stress recovery. These drought induced short roots can be found on either both the tap root and lateral roots or on lateral roots only. These patterns are mostly likely a reflection of the plants' individual ability to maintain meristematic activity under low water potential. This

pos: Cementum It is formed continuously throughout life because a new layer of cementum is deposited to keep the attachment intact as the superficial layer of cementum ages. Cementum on the root ends surrounds the apical foramen and may extend slightly onto the inner wall of the pulp canal. Cementum is secreted by cells called cementoblasts within the root of the tooth and is thickest at the root apex. These cementoblasts develop from undifferentiated mesenchymal cells in the connective tissue of the dental follicle or sac. Unlike ameloblasts and odontoblasts, which leave no cellular bodies in their secreted products, during the later

pos: Plant cell that covers the plant shoot apex, whereas the cortex and vascular tissues arise from innermost layer of the shoot apex known as the "corpus" (L3 layer). The epidermis of roots originates from the layer of cells immediately beneath the root cap. The epidermis of all aerial organs, but not roots, is covered with a cuticle made of polyester cutin or polymer cutan (or both), with a superficial layer of epicuticular waxes. The epidermal cells of the primary shoot are thought to be the only plant cells with the biochemical capacity to synthesize cutin. Plant cell Plant cells are eukaryotic cells

pos: Apical foramen accessory foramina. It is a point of interest in endodontics, as it is considered necessary to thoroughly chemomechanically debride the pulp space to remove all necrotic tissue and minimise bacterial load in the pulp space. Ideally this debridement would terminate exactly at the apical foramen. In reality determining the exact position of the apical foramen is problematic, requiring radiography and/or use of an electronic apex locator to produce a refined estimate. A tooth may have multiple small accessory canals in the root apex area forming an apical delta which can complicate the endodontic problem. An apical constriction is often present.

pos: Hypercementosis Hypercementosis Hypercementosis is an idiopathic, non-neoplastic condition characterized by the excessive buildup of normal cementum (calcified tissue) on the roots of one or more teeth. A thicker layer of cementum can give the tooth an enlarged appearance, which mainly occurs at the apex or apices of the tooth. It is experienced as an uncomfortable sensation in the tooth, followed by an aching pain. It may be noted on radiographs as a radiopaque (or lighter) mass at each root apex. Can be caused by many things. A way to remember the causes is "PIG ON TAP" Local factors- Systemic factors- It

pos: Apical foramen Apical foramen In anatomy the apical foramen is the opening at the apex of the root of a tooth, through which the nerve and blood vessels that supply the dental pulp pass. Thus it represents the junction of the pulp and the periodontal tissue. The average size of the orifice is 0.3 to 0.4 mm in diameter. There can be two or more foramina separated by a portion of dentin and cementum or by cementum only. If more than one foramen is present on each root, the largest one is designated as the apical foramen and the rest are considered

pos: Auxin of plants. However, high concentrations of auxin inhibit root elongation and instead enhance adventitious root formation. Removal of the root tip can lead to inhibition of secondary root formation. Auxin induces shoot apical dominance; the axillary buds are inhibited by auxin, as a high concentration of auxin directly stimulates ethylene synthesis in axillary buds, causing inhibition of their growth and potentiation of apical dominance. When the apex of the plant is removed, the inhibitory effect is removed and the growth of lateral buds is enhanced. Auxin is sent to the part of the plant facing away from the light, where

pos: Plant development roots and buds are very important when people propagate plants via cuttings, layering, tissue culture. Plant hormones, termed auxins, are often applied to stem, shoot or leaf cuttings to promote adventitious root formation, e.g. African violet and sedum leaves and shoots of poinsettia and coleus. Propagation via root cuttings requires adventitious bud formation, e.g. in horseradish and apple. In layering, adventitious roots are formed on aerial stems before the stem section is removed to make a new plant. Large houseplants are often propagated by air layering. Adventitious roots and buds must develop in tissue culture propagation of plants. The genetics

pos: Root red to far red light to lower. The phytochrome PhyA that senses this Red to Far Red light ratio is localized in both the root system as well as the shoot system of plants, but through knockout mutant experimentation, it was found that root localized PhyA does not sense the light ratio, whether directly or axially, that leads to changes in the lateral root architecture. Research instead found that shoot localized PhyA is the phytochrome responsible for causing these architectural changes of the lateral root. Research has also found that phytochrome completes these architectural changes through the manipulation of auxin

pos: Phytomer leaf primordia initiation. Since many more leaf primordia are initiated than leaves develop, the plastochron develops at a much faster rate (sometimes as much as twice as quickly) as the phyllochron. Initially, a young plant will only produce phytomers at its apical meristems but later in development, secondary meristems will begin to form and phytomers will be formed on this lateral plant growth. Phytomer Phytomers are functional units of a plant, continually produced by root and shoot meristems throughout a plant's vegetative life-cycle. The phytomer unit originates at the shoot (or root) apex, and a typical phytomer consists of a

pos: Organogenesis neural tube, and surface ectoderm is sometimes referred to as neurulation and the embryo in this phase is the neurula. The coelom of the body forms from a split of the mesoderm along the somite axis In plants, organogenesis, which is simply the process of forming new organs, occurs continuously and only stops when the plant dies. In the shoot, the shoot apical meristems regularly produce new lateral organs (leaves or flowers) and lateral branches. In the root, new lateral roots form from weakly differentiated internal tissue (e.g. the xylem-pole pericycle in the model plant "Arabidopsis thaliana"). "In vitro" and

pos: Cotyledon termed dicotyledonous ("dicots"). In the case of dicot seedlings whose cotyledons are photosynthetic, the cotyledons are functionally similar to leaves. However, true leaves and cotyledons are developmentally distinct. Cotyledons are formed during embryogenesis, along with the root and shoot meristems, and are therefore present in the seed prior to germination. True leaves, however, are formed post-embryonically (i.e. after germination) from the shoot apical meristem, which is responsible for generating subsequent aerial portions of the plant. The cotyledon of grasses and many other monocotyledons is a highly modified leaf composed of a "scutellum" and a "coleoptile". The scutellum is a tissue

pos: Ectomycorrhiza shown to have beneficial effects upon the establishment of ectomycorrhizal symbioses. Some of these bacteria, known as Mycorrhiza helper bacteria (MHBs), have been shown to stimulate EcM formation, root and shoot biomass. The presence of higher levels of ergosterol in the soil indicate that MHBs may be promoting fungal growth, as well, thereby generating an increase in mycelial tissue and hyphae capable of exploring greater soil volumes. The mechanisms by which these bacteria stimulate mycorrhizal formation are unclear. However, some mechanistic hypotheses include the softening of cell walls to make root cells more receptive, stimulation of short root formation in

pos: Canine space maxilla above the level of attachment of the levator anguli oris muscle. This is more likely if the tooth root is long (the maxillary canine has the longest root of all the teeth), and its apex lies at a level above the muscle attachment. Canine space The canine space (also termed the infra-orbital space), is a fascial space of the head and neck (sometimes also termed fascial spaces or tissue spaces). It is a thin potential space on the face, and is paired on either side. It is located between the levator anguli oris muscle inferiorly and the levator labii

pos: Somatic embryogenesis transferred to a medium with low or no auxin, these cells can then develop into mature embryos. Germination of the somatic embryo can only occur when it is mature enough to have functional root and shoot apices Factors and mechanisms controlling cell differentiation in somatic embryos are relatively ambiguous. Certain compounds excreted by plant tissue cultures and found in culture media have been shown necessary to coordinate cell division and morphological changes. These compounds have been identified by Chung et al. as various polysaccharides, amino acids, growth regulators, vitamins, low molecular weight compounds and polypeptides. Several signaling molecules known to

pos: Phloem the mid-vein extending into the cotyledonary node, which constitutes the first appearance of a leaf in angiosperms, where it forms continuous strands. The hormone auxin, transported by the protein PIN1 is responsible for the growth of those protophloem strands, signaling the final identity of those tissues. SHORTROOT(SHR), and microRNA165/166 also participate in that process, while Callose Synthase 3(CALS3), inhibits the locations where SHORTROOT(SHR), and microRNA165 can go. In the embryo, root phloem develops independently in the upper hypocotyl, which lies between the embryonic root, and the cotyledon. In an adult, the phloem originates, and grows outwards from, meristematic cells in

pos: Meloidogyne arenaria but to lower pH resulting from carbonic acid formed from the CO in solution. The second juvenile (J2) penetrates zone of elongation by mechanical (stylet thrusts) and probably chemical (cellulase and pectinase) means. It moves between, rather than through, cortical cells towards root apex, turns at the meristem, and migrates back to the vascular cylinder in the zone of cell differentiation. Once the J2 is in the root, they migrate intracellularly to the provascular cells and begin to parasitize cells within 24 hours. The nematode initiates formation of the giant cell (also called a nurse cell) from potential vascular tissue.

pos: Polar auxin transport PIN proteins is coordinated between neighbouring cells. As a result, the PIN proteins generate a directional flow of auxin at the tissue and organ scale. This PIN-generated flow is called auxin polar transport. For example, the cells located in the vasculature (at the center) of the root all show PIN1 proteins on their basal membrane only (i.e. on their lower side). As a result, in the root vasculature, auxin is transported directionally from the shoot to the root tip (i.e. downwards). Auxin it-self plays a central role in PIN protein polarity establishment. The regulation of PIN localisation by auxin creates

pos: Dental anatomy the root are referred to as apical. The tissue surrounding apex is called periapical. The words mesial and distal are also used as descriptions. "Mesial" signifies a surface closer to the median line of the face, which is located on a vertical axis between the eyes, down the nose, and between the contact of the central incisors. Surfaces further away from the median line are described as distal. A cusp is an elevation on an occlusal surface of posterior teeth and canines. It contributes to a significant portion of the tooth's surface. Canines have one cusp. Maxillary premolars and the

pos: Spent potlining of spent pot liner (SPL) and its main components on human leukocytes and meristematic cells of Allium cepa. Water, Air, and Soil Pollution, 227(5), 1–10. Palmieri,M. J., Andrade-Vieira, L. F., Campos, J. M. S., Gedraite, L. S.,&Davide, L. C. (2016). Cytotoxicity of spent pot liner on Allium cepa root tip cells: a comparative analysis in meristematic cell type on toxicity bioassays, Ecotoxicology and Environmental Safety, 133, 442–447. Palmieri, M. J., Luber, J., Andrade-Vieira, L. F., & Davide, L. C. (2014). Cytotoxic and phytotoxic effects of the main chemical components of spent pot-liner: a comparative approach, Mutation Research, 763, 30–35. Pawlek,

pos: Human tooth development they produce. The origin of the formative cementoblasts is believed to be different for cellular cementum and acellular cementum. One of the major current hypotheses is that cells producing cellular cementum migrate from the adjacent area of bone, while cells producing acellular cementum arise from the dental follicle. Nonetheless, it is known that cellular cementum is usually not found in teeth with one root. In premolars and molars, cellular cementum is found only in the part of the root closest to the apex and in interradicular areas between multiple roots. The periodontium, which is the supporting structure of a tooth,

pos: Digitalis thapsi than those found in "D. purpurea". According to Dutch botanist Herman Boerhaave, "Digitalis" species are highly poisonous if directly ingested. All parts are poisonous. Besides normal cultivation, "D. thapsi" has been propagated using explant culture, a technique employed for the isolation of cells from piece(s) of tissue for harvesting. Auxins NAA, 2,4-D and IAA alone or combined with BA produced a callus. NAA caused root formation and BA shoot formation. NAA and BA combined induced organ generation much effectively. Plantlets obtained this way had a survival rate of 70%. Joseph Gottlieb Kölreuter, a German botanist, observed that "D. thapsi" had

pos: Root cap Root cap The root cap is a type of tissue at the tip of a plant root. It is also called calyptra. Root caps contain statocytes which are involved in gravity perception in plants. If the cap is carefully removed the root will grow randomly. The root cap protects the growing tip in plants. It secretes mucilage to ease the movement of the root through soil, and may also be involved in communication with the soil microbiota. The purpose of the root cap is to enable downward growth of the root, with the root cap covering the sensitive tissue in

pos: Aerenchyma Aerenchyma Aerenchyma is a spongy tissue that forms spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. The channels of air-filled cavities (see image to right) provide a low-resistance internal pathway for the exchange of gases such as oxygen and ethylene between the plant above the water and the submerged tissues. Aerenchyma is also widespread in aquatic and wetland plants which must grow in hypoxic soils. When soil is flooded, hypoxia develops, as soil microorganisms consume oxygen faster than diffusion occurs. The presence of hypoxic

pos: Propagule infectious propagules are carried in droplets of host saliva or mucus that are expelled during coughing or sneezing. In horticulture, a propagule is any plant material used for the purpose of plant propagation. In asexual reproduction, a propagule is often a stem cutting. In some plants, a leaf section or a portion of root can be used. In sexual reproduction, a propagule is a seed or spore. In micropropagation, a type of asexual reproduction, any part of the plant may be used, though it is usually a highly meristematic part such as root and stem ends or buds. Propagule In

pos: Rice millimho/cm or dS/m. The critical ECe value of 5.5 dS/m in the figure, obtained from measurements in farmers' fields, indicates that the rice crop is slightly salt sensitive. Producing rice in paddies is harmful for the environment due to the release of methane by methanogenic bacteria. These bacteria live in the anaerobic waterlogged soil, and live off nutrients released by rice roots. Researchers have recently reported in "Nature" that putting the barley gene SUSIBA2 into rice creates a shift in biomass production from root to shoot (above ground tissue becomes larger, while below ground tissue is reduced), decreasing the methanogen

pos: Scaling and root planing and root planing, periodontal cleaning, or deep cleaning. These names all refer to the same procedure. The term "deep cleaning" originates from the fact that pockets in patients with periodontal disease are literally deeper than those found in individuals with healthy periodontia. Such scaling and root planing may be performed using a number of dental tools, including ultrasonic instruments and hand instruments, such as periodontal scalers and curettes. The objective for periodontal scaling and root planing is to remove dental plaque and calculus (tartar), which house bacteria that release toxins which cause inflammation to the gum tissue and surrounding bone.

pos: Root canal the center of the roots, similar to the way pencil lead runs through a pencil. The pulp receives nutrition through the blood vessels, and sensory nerves carry signals back to the brain. A tooth can be relieved from pain if there is irreversible damage to the pulp, via root canal treatment. Root canal anatomy consists of the pulp chamber and root canals. Both contain the dental pulp. The smaller branches, referred to as accessory canals, are most frequently found near the root end (apex), but may be encountered anywhere along the root length. The total number of root canals per

pos: Pterolonche inspersa the root tissue. As they reach the root cortex, they spin a silken tube and feed from within the tube. Mature larvae overwinter in the roots. In spring, a silken tube is made above the soil surface in which pupation takes place. Pterolonche inspersa Pterolonche inspersa (brown-winged knapweed root moth) is a moth of the family Pterolonchidae. It is found in Portugal, Spain, France, Italy, Sardinia, the Czech Republic, Slovakia, Hungary, Bulgaria, Greece and Crete. It was released as a biological control agent for knapweed in Colorado, Montana, and Oregon and 1986, but there is no known establishment in the

pos: Root microbiome that live within plant tissue. They may colonize inter-cellular spaces, the root cells themselves, or both. Rhizobia and dark septate endophytes (which produce melanin, an antioxidant that may provide resilience against a variety of environmental stresses) are famous examples. Archaea are traditionally thought of as microbes belonging to extreme environments. Though they are found in plant roots, little is known about their effect on plant health or their role in the root microbiome. There is an ongoing debate regarding what mechanisms are responsible for assembling individual microbes into communities. There are two primary competing hypotheses. One is that "everything is

pos: Cold hardening cell membrane detect the temperature drop, and promotes expression of low temperature responsible genes in "alfalfa" and "arabidopsis". The response to the change in calcium elevation depends on the cell type and stress history. Shoot tissue will respond more than a root cells, and a cell that already is adapted to cold stress will respond more than one that has not been through cold hardening before. Light doesn't control the onset of cold hardening directly, but shortening of daylight is associated with fall, and starts production of reactive oxygen species and excitation of photosystem 2, which influences low-temp signal transduction

pos: Kudzu successful long-term control of kudzu, destroying the underground system, which can be extremely large and deep, is not necessary. Only killing or removing the kudzu root crown and all rooting runners is needed. The root crown is a fibrous knob of tissue that sits on top of the roots. Crowns form from multiple vine nodes that root to the ground, and range from pea- to basketball-sized. The older the crowns, the deeper they tend to be found in the ground. Nodes and crowns are the source of all kudzu vines, and roots cannot produce vines. If any portion of a

pos: Texas root rot as sclerotia or as mycelium on dead plant tissue. Once spring to early summer arrives, germination phase with hyphae growth continues. Following this, root colonization occurs. In Mid and late summer you begin to see the disease at its infectious stage, which is when you start to observe associated symptoms. The pathogen will penetrate the host, and colonize plant root tissue causing root rot. This initially causes the first symptoms of chlorotic leaves and eventually wilting. The pathogen will then eventually disseminate infecting neighboring plants, with infected plant tissue serving as a secondary inoculum fueling the disease. In situation of

pos: Dens evaginatus pulp and periapex assessment should be done every 3–4 months until the apex matures. When there is signs of adequate pulp recession, tubercle can be removed and tooth can be restored. For teeth with inflamed pulp and mature apex, conventional root canal treatment could be carried out and restored accordingly. For teeth with inflamed pulp and immature apex, shallow MTA pulpotomy could be performed and then restore with glass ionomer and composite. For teeth with necrotic pulp and mature apex, conventional root canal therapy could be done and restored. For teeth with necrotic pulp and immature apex, MTA root-end barrier

pos: Periapical periodontitis Periapical periodontitis Periapical periodontitis (also termed apical periodontitis, AP, or periradicular periodontitis) is an acute or chronic inflammatory lesion around the apex of a tooth root which is usually caused by bacterial invasion of the pulp of the tooth. The term is derived from "peri-" meaning "around", "apical" referring to the apex of the root (the tip of the root), and "-itis" meaning a disease characterized by inflammation. Periapical periodontitis can be considered a sequela in the natural history of dental caries (tooth decay), irreversible pulpitis and pulpal necrosis, since it is the likely outcome of untreated dental caries, although

pos: Boletus abruptibulbus bulbous base. It has pseudorrhiza (cord-like structures resembling a plant root) that are long. The stem surface is dry and smooth except for a powdery region near the apex. The top of the stem is yellow, but it gradually becomes reddish approaching the bulbous base. The stem tissue is pale yellow, although tunnels dug by insect larvae are reddish brown. A drop of dilute ammonia (as a 12% NHOH solution) placed on the cap surface immediately turns dark red. If placed on the bulbous part of the stem base of a dried specimen, it will turn dark for roughly 15

pos: Interleukin 31 skin diseases, have been found to have elevated levels of IL-31 mRNA in patient biopsies. Analysis of the tissue distribution of the IL-31 receptor complex found that IL-31RA is abundant in dorsal root ganglia of different human tissues. Dorsal root ganglia is where the cell bodies of primary sensory neurons reside. Dorsal root ganglia are also believed to be where the "itch" sensation originates. These findings support the elevated levels of IL-31 in skin biopsies of pruritic skin diseases. A monoclonal antibody against IL-31 named Lokivetmab is available for the treatment of canine atopic dermatitis. Interleukin 31 Interleukin-31 (IL-31) is

pos: Ectomycorrhiza outward from the mantle into the soil, fulfilling the role of the suppressed root hairs by increasing the surface area of the colonized root. These hyphae can spread out singly, or in an aggregate arrangement known collectively as a rhizomorph. Much as the Hartig net and mantle, composite hyphal organs can display a wide range of structural difference. Some rhizomorphs are simply parallel, linear collections of hyphae. Others yield more complex organization such as aggregates where the central hyphae possess enlarged diameters, or exhibiting apically extending hyphae that superficially resemble meristematic activity. The extramatrical mycelia of ectomycorrhizas function largely as

pos: Root canal in these areas. Thus, the image of root canals having a smooth, conical shape is generally too idealistic and underestimates the reach of root canal instrumentation. The space inside the root canals is filled with a highly vascularized, loose connective tissue, called dental pulp. The dental pulp is the tissue of which the dentin portion of the tooth is composed. The dental pulp helps complete formation of the secondary teeth (adult teeth) one to two years after eruption into the mouth. The dental pulp also nourishes and hydrates the tooth structure, making the tooth more resilient, less brittle and less

pos: Stele (biology) Most seed plant stems possess a vascular arrangement which has been interpreted as a derived siphonostele, and is called a There is also a variant of the eustele found in monocots like maize and rye. The variation has numerous scattered bundles in the stem and is called an atactostele (characterestic of monocot stem). However, it is really just a variant of the eustele. Stele (biology) In a vascular plant, the stele is the central part of the root or stem containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue (pith) and a pericycle,

pos: Root under dense vegetation, the presence of other vegetation nearby will cause the plant to avoid lateral growth and experience an increase in upward shoot, as well as downward root growth. In order to escape shade, plants adjust their root architecture, most notably by decreasing the length and amount of lateral roots emerging from the primary root. Experimentation of mutant variants of Arabidospis thaliana found that plants sense the Red to Far Red light ratio that enters the plant through photoreceptors known as phytochromes. Nearby plant leaves will absorb red light and reflect far- red light which will cause the ratio

pos: Regenerative endodontics the tooth which allows the root to complete formation. Apexification, stimulates cells in the periapical area of the tooth to form a dentin-like substance over the apex. Both improve the long-term prognosis for a forming tooth over root canal alone. Necrotic pulp and open apex can be revitalized with platelet rich fibrin. King's College London published in January 2017 on the regeneration of dentine with collagen sponge filled with glycogen synthase kinase (GSK-3) Regenerative endodontics Regenerative endodontics is the use of biologically based procedures designed to replace damaged tooth structures such as dentin, root structures and cells of the pulp-dentin

pos: Vanilla too much shade favor disease development. Vanilla is susceptible to many fungal and viral diseases. "Fusarium", "Sclerotium", "Phytophthora", and "Colletrotrichum" species cause rots of root, stem, leaf, bean, and shoot apex. These diseases can be controlled by spraying Bordeaux mixture (1%), carbendazim (0.2%) and copper oxychloride (0.2%). Biological control of the spread of such diseases can be managed by applying to the soil "Trichoderma" ( per plant in the rhizosphere) and foliar application of pseudomonads (0.2%). Mosaic virus, leaf curl, and cymbidium mosaic potex virus are the common viral diseases. These diseases are transmitted through the sap, so affected plants

pos: Root cap the root. Also, the root cap enables geoperception or gravitropism. This allows the plant to grow downwards (with gravity) or upwards (against gravity). The root cap is absent in some parasitic plants and some aquatic plants, in which a sac-like structure called the "root pocket" may form instead. Root cap The root cap is a type of tissue at the tip of a plant root. It is also called calyptra. Root caps contain statocytes which are involved in gravity perception in plants. If the cap is carefully removed the root will grow randomly. The root cap protects the growing tip

pos: Electronic apex locator defines humidity of the canal and immediately adapts for dry or wet canal. On this way is possible to be measured as in dry and in additional wetted canals as well, canals with blood or exudates, canals with still not-extirpated pulp. Electronic apex locator An electronic apex locator is an electronic device used in endodontics determine the position of the apical constriction and thus determine the length of the root canal space. The apex of the root has a specific resistance to electrical current, and this is measured using a pair of electrodes typically hooked into the lip and attached

pos: Lujan–Fryns syndrome subunits are only required for regulation of transcription in particular tissues or cells. Currently, the exact mechanism by which dysfunction of "MED12" results in LFS and its associated neuropsychopathic and physical characteristics is unclear. Marfanoid habitus, a highly arched palate and several other features of LFS can be found with Marfan syndrome, a connective tissue disorder. The finding of aortic root dilation in both disorders suggests that a mutation in an unspecified connective tissue regulating gene may contribute to the etiology of LFS. A number of interesting experimental results have been obtained by studying "MED12" mutations in the zebrafish, an

neg: Tissue (biology) Each cell contains a dense cytoplasm and a prominent nucleus. Dense protoplasm of meristematic cells contains very few vacuoles. Normally the meristematic cells are oval, polygonal or rectangular in shape. Meristematic tissue cells have a large nucleus with small or no vacuoles, they have no intercellular spaces. Permanent tissues may be defined as a group of living or dead cells formed by meristematic tissue and have lost their ability to divide and have permanently placed at fixed positions in the plant body. Meristematic tissues that take up a specific role lose the ability to divide. This process of taking up

neg: Meristem exhibits a nodule regulation phenotype though it is not yet known how this relates to the other AON receptor kinases. Meristem A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of a plant and are responsible for growth. Differentiated plant cells generally cannot divide or produce cells of a different type. Meristematic cells are incompletely or not at all differentiated, and are capable of continued cellular division. Therefore, cell division in the meristem is required to provide new

neg: Meristem Meristem A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of a plant and are responsible for growth. Differentiated plant cells generally cannot divide or produce cells of a different type. Meristematic cells are incompletely or not at all differentiated, and are capable of continued cellular division. Therefore, cell division in the meristem is required to provide new cells for expansion and differentiation of tissues and initiation of new organs, providing the basic structure of the plant body.

neg: Tissue (biology) a permanent shape, size and a function is called cellular differentiation. Cells of meristematic tissue differentiate to form different types of permanent tissues. There are 3 types of permanent tissues: A group of cells which are similar in origin; similar in structure and similar in function are called simple permanent tissue. They are of four types: Parenchyma ("para" - 'beside'; "enchyma" - 'tissue') is the bulk of a substance. In plants, it consists of relatively unspecialized living cells with thin cell walls that are usually loosely packed so that intercellular spaces are found between cells of this tissue. These are

neg: Tissue (biology) roots. It is in these regions that meristematic tissue is present. Cells in these tissues are roughly spherical or polyhedral, to rectangular in shape, and have thin cell walls. New cells produced by meristem are initially those of meristem itself, but as the new cells grow and mature, their characteristics slowly change and they become differentiated as components of the region of occurrence of meristematic tissues, they are classified as: The cells of meristematic tissues are similar in structure and have thin and elastic primary cell wall made up of cellulose. They are compactly arranged without inter-cellular spaces between them.

neg: Sugarcane smut create four haploid sporidia. Sugarcane smut is bipolar and therefore produces two different mating types of sporida. For infection to occur, two sporida from different mating types must come together and form a dikaryon. This dikaryon then produces hyphae that penetrate the bud scales of the sugarcane plant and infect the meristematic tissue. The fungus grows within the meristematic tissue and induces formation of flowering structures which it colonises to produce its teliopores. The flowering structures, usually typical grass arrows, are transformed into a whip like sorus that grows out between the leaf sheaths. At first it is covered by

neg: Root nodule full function in some of them: Two main types of nodule have been described: determinate and indeterminate. Determinate nodules are found on certain tribes of tropical legume such as those of the genera "Glycine" (soybean), "Phaseolus" (common bean), and "Vigna". and on some temperate legumes such as Lotus. These determinate nodules lose meristematic activity shortly after initiation, thus growth is due to cell expansion resulting in mature nodules which are spherical in shape. Another types of determinate nodule is found in a wide range of herbs, shrubs and trees, such as Arachis (peanut). These are always associated with the axils

neg: Plant embryogenesis The important component of the globular phase is the introduction of the rest of the primary meristematic tissue. The protoderm was already introduced during the sixteen cell stage. According to Evert and Eichhorn, the ground meristem and procambium are initiated during the globular stage. The ground meristem will go on to form the ground tissue, which includes the pith and cortex. The procambium will eventually form the vascular tissue, which includes the xylem and phloem. According to Evert and Eichhorn, the heart stage is a transition period where the cotyledons finally start to form and elongate. It is given this

neg: Plant evolutionary developmental biology apical cells do contain organelles like large vacuoles and starch grains, like the angiosperm meristematic cells. Pteridophytes, like fern, on the other hand, do not possess a multicellular apical meristem. They possess a tetrahedral apical cell, which goes on to form the plant body. Any somatic mutation in this cell can lead to hereditary transmission of that mutation. The earliest meristem-like organization is seen in an algal organism from group "Charales" that has a single dividing cell at the tip, much like the pteridophytes, yet simpler. One can thus see a clear pattern in evolution of the meristematic tissue, from

neg: Laticifer Laticifer A laticifer is a type of elongated secretory cell found in the leaves and/or stems of plants that produce latex and rubber as secondary metabolites. Laticifers may be divided into: Non-articulated laticifers begin their growth from the meristematic tissue of the embryo, termed the laticifer initial, and can exhibit continual growth throughout the lifetime of the plant. Laticifer tubes have irregularly edged walls and a larger inner diameter than the surrounding parenchyma cells. In the development of the cell, elongation occurs via karyokinesis and no cell plate develops resulting in coenocytic cells which extend throughout the plant. These cells

neg: Gleichenia abscida Gleichenia abscida Gleichenia abscida, commonly known as dwarf coral fern, is an uncommon alpine fern found in southwestern Tasmania. Described by English born dentist and botanist Leonard Rodway, that which distinguishes "G. abscida" the most from all other species of "Gleichenia" is its frond. While each other species of "Gleichenia" have a repetitively branching frond, "G. abscida"'s frond consists of just two blades, with the apical axil between these two blades lacking meristematic tissue. Multiple stipes (25–40), 9–46 cm long, with fronds up to 65 cm in length, arise from long creeping rhizomes 2.5–3.5 mm in diameter. Scaly rounded pinnules

neg: Gleichenia abscida 1–2 mm across, with flat adaxial surfaces and strongly recurved into an abaxial pouch, hold sori of 2–4 sporangia. Gleichenia abscida Gleichenia abscida, commonly known as dwarf coral fern, is an uncommon alpine fern found in southwestern Tasmania. Described by English born dentist and botanist Leonard Rodway, that which distinguishes "G. abscida" the most from all other species of "Gleichenia" is its frond. While each other species of "Gleichenia" have a repetitively branching frond, "G. abscida"'s frond consists of just two blades, with the apical axil between these two blades lacking meristematic tissue. Multiple stipes (25–40), 9–46 cm long, with

neg: CLE peptide they do not possess any defined end status. In that sense, the meristematic cells are frequently compared to the stem cells in animals, which have an analogous behavior and function. Within plants SAM cells play a major role in the overall growth and development, this is due to the fact that all cells making up the major parts of the plant come from the shoot apical meristem (SAM). There are three different important area found within the SAM and they include the central zone (CZ), the peripheral zone (PZ), and the rib meristem (RM). Each of these areas play an

neg: Chloroplast etioplasts. In fact, a typical shoot meristematic plant cell contains only 7–20 proplastids. These proplastids differentiate into chloroplasts, which divide to create the 30–70 chloroplasts found in a mature photosynthetic plant cell. If the cell divides, chloroplast division provides the additional chloroplasts to partition between the two daughter cells. In single-celled algae, chloroplast division is the only way new chloroplasts are formed. There is no proplastid differentiation—when an algal cell divides, its chloroplast divides along with it, and each daughter cell receives a mature chloroplast. Almost all chloroplasts in a cell divide, rather than a small group of rapidly dividing

neg: Meristem Securities Meristem Securities Meristem Securities Limited is a Nigerian Capital Market Conglomerate regulated by the Securities and Exchange Commission (SEC) based in Lagos State, Nigeria. Formerly known as Great Africa Securities Limited founded in 2003, the company had a change of name to Meristem in 2005. The company has five subsidiaries; Meristem Stockbrokers, Meristem Wealth, Meristem Registrars and Probate Services, Meristem Capital and Meristem Trustees. The company name is familiarized with an agricultural word. Meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. The organization reflects this

neg: Laticifer desert species, "Bursera schlechtendalii", pressurizes the canals right where leaves attach to the stem so that when a grazer eats a leaf latex shoots out. This process is termed the “squirt gun” defense. Laticifer A laticifer is a type of elongated secretory cell found in the leaves and/or stems of plants that produce latex and rubber as secondary metabolites. Laticifers may be divided into: Non-articulated laticifers begin their growth from the meristematic tissue of the embryo, termed the laticifer initial, and can exhibit continual growth throughout the lifetime of the plant. Laticifer tubes have irregularly edged walls and a larger

neg: Callus (cell biology) callus is usually derived from somatic tissues. The tissues used to initiate callus formation depends on plant species and which tissues are available for explant culture. The cells that give rise to callus and somatic embryos usually undergo rapid division or are partially undifferentiated such as meristematic tissue. In alfalfa, "Medicago truncatula", however callus and somatic embryos are derived from mesophyll cells that undergo dedifferentiation. Plant hormones are used to initiate callus growth. Specific auxin to cytokinin ratios in plant tissue culture medium give rise to an unorganized growing and dividing mass of callus cells. Callus cultures are often broadly

neg: Tissue (biology) layer of cells) or stratified (multiple layers of cells). However, other cellular features, such as cilia may also be described in the classification system. Some common kinds of epithelium are listed below: In plant anatomy, tissues are categorized broadly into three tissue systems: the epidermis, the ground tissue, and the vascular tissue. Plant tissues can also be divided differently into two types: Meristematic tissue consists of actively dividing cells, and leads to increase in length and thickness of the plant. The primary growth of a plant occurs only in certain, specific regions, such as in the tips of stems or

neg: Ground tissue seeds. Parenchyma cells are living cells and may remain meristematic at maturity—meaning that they are capable of cell division if stimulated. They have thin and flexible cellulose cell walls, and are generally polyhedral when close-packed, but can be roughly spherical when isolated from their neighbours. They have large central vacuoles, which allow the cells to store and regulate ions, waste products, and water. Tissue specialised for food storage is commonly formed of parenchyma cells. Parenchyma cells have a variety of functions: The shape of parenchyma cells varies with their function. In the spongy mesophyll of a leaf, parenchyma cells range

neg: Speckle tracking echocardiography which defines motion around a particular point in tissue as it revolves through time and space. Throughout the cardiac cycle, the end-diastolic tissue dimension represents the unstressed initial material length. Speckle tracking is one of two methods for Strain rate imaging, the other being Tissue Doppler. Twist or torsional deformation define the base-to-apex gradient and is the result of myocardial shearing in the circumferential-longitudinal planes such that, when viewed from the apex, the base rotates in a counterclockwise direction. Likewise the LV apex concomitantly rotates in a clockwise direction. During ejection, LV torsion results in the storage of potential energy

neg: Common ostrich heart. It then moves along the coronary groove and continues on into the tissue as interventricular branches toward the apex of the heart. The atria, ventricles, and septum are supplied of blood by this modality. The deep branches of the coronary arteries found within the heart tissue are small and supply the interventricular and right atrioventricular valve with blood nutrients for which to carry out their processes. The interatrial artery of the ostrich is small in size and exclusively supplies blood to only part of the left auricle and interatrial septum. These purkinje fibers (p-fibers) found in the hearts moderator

neg: Aphelenchoides besseyi sum of effective temperatures for the development of one generation is 80 degree-days. "A. besseyi" is an ectoparasitic nematode which means it feeds on the plant tissue externally. This nematode is most often associated with a disease in which the leaves of the rice plant turn white in the meristematic regions followed by necrosis. These nematodes can also cause stunting and sterility with yield losses of up to 50% reported The most common management practice for "A. besseyi" is to maintain clean seed stocks. Since the nematode survives in the seed it is fairly easy to control. Seed can be

neg: Aloe comosa single, unbranched stem which may attain heights of approximately 3 meters. As it matures and grows in height, Aloe comosa retains its dry, dead leaves and forms a tangled skirt or beard. Tree aloe bark differs from woody dicot bark in that it doesn’t have a phellogen, which is the meristematic tissue that differentiates into the bark. In essence, aloe bark is actually overlapping, irregular layers of incomplete bark tissues. A study was published in the science journal Oecologia by W. Bond (1983) on the purpose of retaining dead leaves by several species of tree aloe. Researchers before Bond have

neg: Plastid circular, like that of prokaryotic cells. Plastids that contain chlorophyll can carry out photosynthesis and are called chloroplasts. Plastids can also store products like starch and can synthesize fatty acids and terpenes, which can be used for producing energy and as raw material for the synthesis of other molecules. For example, the components of the plant cuticle and its epicuticular wax are synthesized by the epidermal cells from palmitic acid, which is synthesized in the chloroplasts of the mesophyll tissue. All plastids are derived from proplastids, which are present in the meristematic regions of the plant. Proplastids and young chloroplasts

neg: Plant embryogenesis sixteen cell stage. The four domains are still present, but they are more defined with the presence of more cells. The important aspect of this stage is the introduction of the protoderm, which is meristematic tissue that will give rise to the epidermis. The protoderm is the outermost layer of cells in the embryo proper. The name of this stage is indicative of the embryo's appearance at this point in embryogenesis; it is spherical or globular. Stage III, in the photograph above, depicts what the embryo looks like during the globular stage. 1 is indicating the location of the endosperm.

neg: Ground tissue the layers of secondary material seem like tubes, of which the outer one is always longer and older than the next. After completion of growth, the missing parts are supplemented, so that the wall is evenly thickened up to the tips of the fibers. Fibers usually originate from meristematic tissues. Cambium and procambium are their main centers of production. They are usually associated with the xylem and phloem of the vascular bundles. The fibers of the xylem are always lignified, while those of the phloem are cellulosic. Reliable evidence for the fibre cells' evolutionary origin from tracheids exists. During evolution

neg: Sugarcane smut in all countries that lie between 20 degrees north and south of the equator. The pathogen does well in hot dry weather for most of the disease cycle but requires wet conditions for teliospores to germinate. Plant disease resistance is the result of coevolution between the plant and pathogen. During Ustilago scitaminea infection, the fungus grows within the meristematic tissue and induces formation of flowering structures, which it colonises to produce its teliopores. The flowering structures, usually typical grass panicles, are transformed into a whip-like sorus that grows rapidly and protrudes out between the leaf sheaths. The development of sugarcane

neg: Geastrum when dry, it is described as hygroscopic. In some species, the inner peridium is borne on a stalk or pedicel. The columella is a column-like clump of sterile tissue to be found inside the inner peridium. The network of fertile tissue inside the inner peridium, the capillitium, arises from the columella. The mouth in most species of "earth-stars" is quite prominent, often arising as a small cone at the apex of the inner peridium. It may be even or sulcate (grooved). They are generally not toxic but considered non-edible due to their fibrous texture in the mature stage at which

neg: Evolutionary history of plants height. Greater height provided a competitive advantage in the harvesting of sunlight for photosynthesis, overshadowing of competitors and in spore distribution, as spores (and later, seeds) could be blown for greater distances if they started higher. An effective vascular system was required in order to achieve greater heights. To attain arborescence, plants had to develop woody tissue that provided both support and water transport, and thus needed to evolve the capacity for secondary growth. The stele of plants undergoing secondary growth is surrounded by a vascular cambium, a ring of meristematic cells which produces more xylem on the inside and

neg: Dorothea Pertz advocating for women to be fellows. After Darwin's retirement, Pertz was encouraged by Frederick Blackman to undertake research on meristematic tissue, but after a year observing germinating seeds her results were inconclusive. She abandoned research, possibly over disappointment, though Agnes Arber claimed "she came to recognize that the plant physiology of the twentieth century was developing on lines widely divergent from those on which she had been educated and that it demanded a grasp of mathematics, physics, and chemistry, which she did not possess." After Pertz had given up research, at Blackman's suggestion she worked on indexing German literature on

neg: Plant embryogenesis and gametophyte plant; including the growth of embryos in seedlings, and to meristematic tissues, which are in a persistently embryonic state, to the growth of new buds on stems. In both gymnosperms and angiosperms, the young plant contained in the seed, begins as a developing egg-cell formed after fertilization (sometimes without fertilization in a process called apomixis) and becomes a plant embryo. This embryonic condition also occurs in the buds that form on stems. The buds have tissue that has differentiated but not grown into complete structures. They can be in a resting state, lying dormant over winter or when

neg: Sisal position. These methods offer no potential for genetic improvement. In vitro multiplication of selected genetic material using meristematic tissue culture (MST) offers considerable potential for the development of improved genetic material. Fibre is extracted by a process known as decortication, where leaves are crushed, beaten, and brushed away by a rotating wheel set with blunt knives, so that only fibres remain. Alternatively, in East Africa, where production is typically on large estates, the leaves are transported to a central decortication plant, where water is used to wash away the waste parts of the leaf. The fibre is then dried, brushed