In these cells, the limited proliferation capacity reflects a progressive shortening of the cell's telomeres, the repetitive DNA sequences and associated proteins that cap the ends of each chomosome discussed in Chapter 5. Human somatic cells have turned off the enzyme , called telomerase , that normally maintains the telomeres, which is why their telomeres shorten with each cell division.
Some human cells, however, are not immortalized by this trick. Although their telomeres remain long, they still stop dividing after a limited number of divisions because the culture conditions activate cell-cycle checkpoint mechanisms discussed in Chapter 17 that arrest the cell cycle. In order to immortalize these cells, one has to do more than introduce telomerase. One must also inactivate the checkpoint mechanisms, which can be done by introducing certain cancer-promoting oncogenes derived from tumor viruses discussed in Chapter Unlike human cells, most rodent cells do not turn off telomerase and therefore their telomeres do not shorten with each cell division.
In addition, rodent cells can undergo genetic changes in culture that inactivate their checkpoint mechanisms, thereby spontaneously producing immortalized cell lines. Cell lines can often be most easily generated from cancer cells, but these cells differ from those prepared from normal cells in several ways. Cancer cell lines often grow without attaching to a surface, for example, and they can proliferate to a very much higher density in a culture dish.
Similar properties can be induced experimentally in normal cells by transforming them with a tumor-inducing virus or chemical. The resulting transformed cell lines, in reciprocal fashion, can often cause tumors if injected into a susceptible animal. It is important to keep in mind, however, that the cells in both types of cell lines nearly always differ in important ways from their normal progenitors in the tissues from which they were derived.
Some widely used cell lines are listed in Table Among the most promising cell cultures to be developed—from a medical point of view—are the human embryonic stem ES cell lines. These cells, harvested from the inner cell mass of the early embryo, can proliferate indefinitely while retaining the ability to give rise to any part of the body discussed in Chapter ES cells could potentially revolutionize medicine by providing a source of cells capable of replacing or repairing tissues that have been damaged by injury or disease.
Although all the cells in a cell line are very similar, they are often not identical. The genetic uniformity of a cell line can be improved by cell cloning, in which a single cell is isolated and allowed to proliferate to form a large colony. In such a colony, or clone , all the cells are descendants of a single ancestor cell.
One of the most important uses of cell cloning has been the isolation of mutant cell lines with defects in specific genes. Studying cells that are defective in a specific protein often reveals valuable information about the function of that protein in normal cells. Some important steps in the development of cell culture are listed in Table It is possible to fuse one cell with another to form a heterocaryon , a combined cell with two separate nuclei. Typically, a suspension of cells is treated with certain inactivated viruses or with polyethylene glycol, each of which alters the plasma membranes of cells in a way that induces them to fuse.
Heterocaryons provide a way of mixing the components of two separate cells in order to study their interactions. The inert nucleus of a chicken red blood cell , for example, is reactivated to make RNA and eventually to replicate its DNA when it is exposed to the cytoplasm of a growing tissue-culture cell by fusion. The first direct evidence that membrane proteins are able to move in the plane of the plasma membrane discussed in Chapter 10 came from an experiment in which mouse cells and human cells were fused: although the mouse and human cell-surface proteins were initially confined to their own halves of the heterocaryon plasma membrane, they quickly diffused and mixed over the entire surface of the cell.
Eventually, a heterocaryon proceeds to mitosis and produces a hybrid cell in which the two separate nuclear envelopes have been disassembled, allowing all the chromosomes to be brought together in a single large nucleus Figure Although such hybrid cells can be cloned to produce hybrid cell lines, the cells tend to lose chromosomes and are therefore genetically unstable.
For unknown reasons, mouse-human hybrid cells predominantly lose human chromosomes. These chromosomes are lost at random, giving rise to a variety of mouse-human hybrid cell lines, each of which contains only one or a few human chromosomes. This phenomenon has been put to good use in mapping the locations of genes in the human genome : only hybrid cells containing human chromosome 11, for example, synthesize human insulin , indicating that the gene encoding insulin is located on chromosome The production of hybrid cells.
Human cells and mouse cells are fused to produce heterocaryons each with two or more nuclei , which eventually form hybrid cells each with one fused nucleus. These particular hybrid cells are useful for mapping human more In the development of a special type of hybrid cell line revolutionized the production of antibodies for use as tools in cell biology.
The technique involves propagating a clone of cells from a single antibody-secreting B lymphocyte so that a homogeneous preparation of antibodies can be obtained in large quantities. The practical problem, however, is that B lymphocytes normally have a limited life-span in culture. From the resulting heterogeneous mixture of hybrid cells, those hybrids that have both the ability to make a particular antibody and the ability to multiply indefinitely in culture are selected.
These hybridomas are propagated as individual clones, each of which provides a permanent and stable source of a single type of monoclonal antibody Figure This antibody recognizes a single type of antigenic site—for example, a particular cluster of five or six amino acid side chains on the surface of a protein. Their uniform specificity makes monoclonal antibodies much more useful for most purposes than conventional antisera, which generally contain a mixture of antibodies that recognize a variety of different antigenic sites on a macromolecule.
Preparation of hybridomas that secrete monoclonal antibodies against a particular antigen. The most important advantage of the hybridoma technique is that monoclonal antibodies can be made against molecules that constitute only a minor component of a complex mixture. In an ordinary antiserum made against such a mixture, the proportion of antibody molecules that recognize the minor component would be too small to be useful.
But if the B lymphocytes that produce the various components of this antiserum are made into hybridomas, it becomes possible to screen individual hybridoma clones from the large mixture to select one that produces the desired type of monoclonal antibody and to propagate the selected hybridoma indefinitely so as to produce that antibody in unlimited quantities.
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In principle, therefore, a monoclonal antibody can be made against any protein in a biological sample. Once an antibody has been made, it can be used as a specific probe —both to track down and localize its protein antigen and to purify that protein in order to study its structure and function. Because only a small fraction of the estimated 10, —20, proteins in a typical mammalian cell have thus far been isolated, many monoclonal antibodies made against impure protein mixtures in fractionated cell extracts identify new proteins.
With the use of monoclonal antibodies and the rapid protein identification methods we shall describe shortly, it is no longer difficult to identify and characterize novel proteins and genes. The major problem is instead to determine their function, using a set of powerful tools that we discuss in the last sections of this chapter. Conspicuous cell wall protuberances and an accumulation of mitochondria nearby occurred in the horizontally oriented cell walls.
The cytological differences between stalk cells and secretory cells indicate a different function. The dominance of sER suggests its involvement in STL biosynthesis and cell wall protuberances enlarge the surface of the plasmamembrane of secretory cells and may be involved in the secretion processes of STL into the subcuticular space.
Localization of sesquiterpene lactone biosynthesis in cells of capitate glandular trichomes of Helianthus annuus Asteraceae. Capitate glandular trichomes CGT of sunflower, Helianthus annuus, synthesize bioactive sesquiterpene lactones STLs within a short period of only a few days during trichome development. In the current project, the subcellular localization of H. A polyclonal antibody raised against this enzyme was used for immunolabelling. This correlated with the appearance of smooth endoplasmic reticulum in both cell types.
Stalk cells and secretory cells differed in form, size and types of plastids, but both had structures necessary for secretion. Our results indicated that not only secretory cells but also nearly all cells of the CGT were involved in the biosynthesis of STL and that this process was not linked to the presence or absence of a specific type of plastid. Plant sesterterpenoids, an important class of terpenoids, are widely distributed in various plants , including food crops.
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However, little is known about their biosynthesis. Here, we cloned and functionally characterized a plant geranylfarnesyl diphosphate synthase Lc-GFDPS , the enzyme producing the C25 prenyl diphosphate precursor to all sesterterpenoids, from the glandular trichomes of the woody plant Leucosceptrum canum. GFDPS was strongly expressed in glandular trichomes , and its transcript profile was completely in accordance with the sesterterpenoid accumulation pattern. GFDPS is localized to the plastids, and inhibitor studies indicated its use of isoprenyl diphosphate substrates supplied by the 2-C-methyl-d-erythritol 4-phosphate pathway.
Application of a jasmonate defense hormone induced GFDPS transcript and sesterterpenoid accumulation, while reducing feeding and growth of the generalist insect Spodoptera exigua, suggesting that these C25 terpenoids play a defensive role. Phylogenetic analysis suggested that GFDPS probably evolved from plant geranylgeranyl diphosphate synthase under the influence of positive selection. The isolation of GFDPS provides a model for investigating sesterterpenoid formation in other species and a tool for manipulating the formation of this group in plants and other organisms.
Trichomes are widely distributed on surfaces of different organs in the grape genus Vitis and are of taxonomic utility. To explore the morphology, structure and ontogeny of Vitis trichomes , we investigated the diversity and distribution of trichomes in 34 species of Vitis. Two main types of trichomes in Vitis are documented: non- glandular and glandular. Within non- glandular trichomes , ribbon and simple trichomes are found on different vegetative plant organs.
The morphology and ontogeny of these types of trichomes are further examined with light microscopy and scanning electron microscopy. The ultrastructure of the glandular trichomes is explored with transmission electron microscopy. The ribbon trichomes are twisted, greatly elongated and unicellular, and this trichome type may be a morphological synapomorphy of Vitis and its closest tropical relative Ampelocissus and Pterisanthes in Vitaceae.
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The simple trichomes are documented in most species sampled in the genus. The glandular trichomes are multicellular, non-vascularized and composed of both epidermis and subjacent layers. We show that prickles occurring along the stems and petioles of Vitis davidii are modified glandular trichomes. We observed that glandular trichomes of V.
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Transmission electron microscopy indicates that metabolic products accumulate in vacuoles, the cytoplasm and intercellular spaces. We infer that glandular trichomes and young prickles are involved in the secretion of these metabolic products and the intercellular spaces may be the places of temporary storage of these secretions. Monoterpenes in the glandular trichomes of tomato are synthesized from a neryl diphosphate precursor rather than geranyl diphosphate. We identified a cis-prenyltransferase gene, neryl diphosphate synthase 1 NDPS1 , that is expressed in cultivated tomato Solanum lycopersicum cultivar M82 type VI glandular trichomes and encodes an enzyme that catalyzes the formation of neryl diphosphate from isopentenyl diphosphate and dimethylallyl diphosphate.
It encodes an enzyme that uses neryl diphosphate to produce beta-phellandrene as the major product as well as a variety of other monoterpenes. The profile of monoterpenes produced by PHS1 is identical with the monoterpenes found in type VI glands. The data indicate that, contrary to the textbook view of geranyl diphosphate as the "universal" substrate of monoterpene synthases, in tomato glands neryl diphosphate serves as a precursor for the synthesis of monoterpenes. Schilmiller, Anthony L. Comparative glandular trichome transcriptome-based gene characterization reveals reasons for differential - -menthol biosynthesis in Mentha species.
But the information on these genes is not available in Mentha arvensis. To bridge the gap in knowledge on differential biosynthesis of monoterpenes leading to compositional variation in the essential oil of these species, a comparative transcriptome analysis of the glandular trichome GT was carried out.
In addition to the mevalonic acid MVA and methylerythritol phosphate MEP pathway genes, about and different terpene synthases TPSs transcripts were identified from annotation in M. Six isoforms of - -menthol dehydrogenases MD , the last enzyme of the menthol biosynthetic pathway, were identified, cloned and characterized from the transcriptome data three from each species.
Several genes for high value minor monoterpenes could also be identified from the transcriptome data. Nagel, Jana; Culley, Lana K. The glandular trichomes lupulin glands of hop Humulus lupulus synthesize essential oils and terpenophenolic resins, including the bioactive prenylflavonoid xanthohumol.
To dissect the biosynthetic processes occurring in lupulin glands, we sequenced 10, ESTs from four trichome -derived cDNA libraries. ESTs representing enzymes of terpenoid biosynthesis, including all of the steps of the methyl 4-erythritol phosphate pathway, were abundant in the EST data set, as were ESTs for the known type III polyketide synthases of bitter acid and xanthohumol biosynthesis. The xanthohumol biosynthetic pathway involves a key O-methylation step. Four S-adenosyl-l-methionine—dependent O-methyltransferases OMTs with similarity to known flavonoid-methylating enzymes were present in the EST data set.
OMT2 accepted a broad range of substrates, including desmethylxanthohumol, but did not form xanthohumol. Mass spectrometry and proton nuclear magnetic resonance analysis showed it methylated xanthohumol to 4-O-methylxanthohumol, which is not known from hop.
OMT3 was inactive with all substrates tested. The lupulin gland-specific EST data set expands the genomic resources for H. Identification and characterization of two bisabolene synthases from linear glandular trichomes of sunflower Helianthus annuus L. Sunflower is known to produce a variety of bisabolene-type sesquiterpenes and accumulates these substances in trichomes of leaves, stems and flowering parts.
A bioinformatics approach was used to identify the enzyme responsible for the initial step in the biosynthesis of these compounds from its precursor farnesyl pyrophosphate. Based on sequence similarity with a known bisabolene synthases from Arabidopsis thaliana AtTPS12, candidate genes of Helianthus were searched in EST-database and used to design specific primers. PCR experiments identified two candidates in the RNA pool of linear glandular trichomes of sunflower. Their sequences contained the typical motifs of sesquiterpene synthases and their expression in yeast functionally characterized them as bisabolene synthases.
The origin of the two sunflower bisabolene synthase genes from the transcripts of linear trichomes indicates that they may be involved in the synthesis of sesquiterpenes produced in these trichomes. Brassica villosa, a system for studying non- glandular trichomes and genes in the Brassicas. Brassica villosa is a wild Brassica C genome species with very dense trichome coverage and strong resistance to many insect pests of Brassica oilseeds and vegetables.
Transcriptome analysis of hairy B. However, transcripts of the TRY inhibitory gene in hairy B. Several antioxidant, calcium, non-calcium metal and secondary metabolite genes also showed differential expression between these two species. These coincided with accumulation of two alkaloid-like compounds, high levels of calcium, and other metals in B. This first time report on the isolation of large amounts of pure B. Rostkowska, Cristina; Mota, Caroline M.
Artemisia annua is used as a source of artemisinin, a potent therapeutic agent used for the treatment of infectious diseases, chiefly malaria. However, the low concentration from 0. Considering that artemisinin and silicon Si are both stored in A. The experimental design consisted of A. Analysis of foliar macronutrients showed significant increases of nitrogen content only at the highest dose of silicate.
Foliar micronutrients, Si concentrations, and plant height were not affected by any of the silicate doses. However, the dose of kg ha-1 of silicate increased the trichome size, which in turn raised artemisinin concentration in leaves and the infusion. In contrast, the and kg ha-1 doses dramatically decreased artemisinin concentration. HeLa cell treatment with the infusion of A. However, this effect was similar to A. Thus, it can be concluded that, even though Si applied to the soil at kg ha-1 has a positive effect on the A.
Are plant trichomes harmful to predatory insects and mites? Plants may use epidermal hairs trichomes to defend themselves from attack by herbivores. Predatory arthropods may serve as biocontrol agents against herbivores. Whether or not plant trichomes work in concert with predators is undocumented in many cases. We reviewed the peer-reviewed literature Plant trichomes have mixed impacts on predatory insects.
He also suggested t Sideritis montana subsp. The secondary metabolism of this plant has not been fully explored so far. The aim of the present study was to understand the complex mixture of secondary metabolites and the type of secretory structures. The polar constituents were isolated by column chromatography from the ethanolic extract, and their structure was elucidated by NMR and MS.
The plant indumentum was studied by light and scanning electron microscopy. Four different classes of secondary metabolites were isolated, namely flavonoids, caffeoylquinic derivatives, glycosidic hydroquinones and iridoids. The essential oil was mainly characterized by sesquiterpenene hydrocarbons. Peltate and long-capitate hairs were the main sites where terpenes and polar constituents are produced.
The secondary metabolites found in S. The trichomes types observed partially differ from those described in other members of the genus Sideritis. The essential oil showed noteworthy inhibition on tumor cells. Effect of heat shock on ultrastructure and calcium distribution in Lavandula pinnata L. The effects of heat shock HS on the ultrastructure and calcium distribution of Lavandula pinnata secretory trichomes are examined using transmission electron microscopy and potassium antimonate precipitation.
Heat shock is associated with a decrease in calcium precipitates in the trichomes , while the number of precipitates increases in the mesophyll cells. Prolonged exposure to elevated calcium levels may be toxic to the mesophyll cells, while the lack of calcium in the glands cell may deprive them of the normal protective advantages of elevated calcium levels. The inequality in calcium distribution may result not only from uptake from the transpiration stream, but also from redistribution of calcium from the trichomes to the mesophyll cells.
Medium-length methylketones C7-C15 are highly effective in protecting plants from numerous pests. We used a biochemical genomics approach to elucidate the pathway leading to synthesis of methylketones in the glandular trichomes of the wild tomato Lycopersicon hirsutum f glabratum accession PI Although MKS1 does not contain a classical transit peptide, in vitro import assays showed that it was targeted to the stroma of plastids, where fatty acid biosynthesis occurs. Levels of MKS1 transcript, protein, and enzymatic activity were correlated with levels of methylketones and gland density in a variety of tomato accessions and in different plant organs.
Flavonoids are ubiquitous plant aromatic specialized metabolites found in a variety of cell types and organs. Methylated flavonoids are detected in secreting glandular trichomes of various Solanum species, including the cultivated tomato Solanum lycopersicum. Inspection of the sequenced S. A combination of mining genome and cDNA sequences from wild tomato species and S. In parallel, three independent ethyl methanesulfonate mutants in the S. The foliar trichomes of Hypoestes aristata Vahl Sol.
The micromorphology of foliar trichomes of Hypoestes aristata var. This genus belongs to the advanced angiosperm family Acanthaceae, for which few micromorphological leaf studies exist. Results revealed both glandular and non- glandular trichomes , the latter being more abundant on leaf veins, particularly on the abaxial surface of very young leaves. With leaf maturity, the density of non- glandular trichomes decreased.
Glandular trichomes were rare and of two types: long-stalked capitate and globose-like peltate trichomes. Capitate trichomes were observed only on the abaxial leaf surface, while peltate trichomes were distributed on both adaxial and abaxial leaf surfaces. Are leaf glandular trichomes of oregano hospitable habitats for bacterial growth? Phyllospheric bacteria were isolated from microsites around essential-oil-containing glands of two oregano Origanum vulgare subsp. These bacteria, 20 isolates in total, were subjected to bioassays to examine their growth potential in the presence of essential oils at different concentrations.
Although there were qualitative and quantitative differences in the essential oil composition between the two oregano lines, no differences were recorded in their antibacterial activity. In disk diffusion bioassays, four of the isolated strains could grow almost unrestrained in the presence of oregano oil, another five proved very sensitive, and the remaining 11 showed intermediate sensitivity. The strain least inhibited by oregano essential oil was further identified by complete16s rRNA gene sequencing as Pseudomonas putida.
It was capable of forming biofilms even in the presence of oregano oil at high concentrations. Resistance of P. When inoculated on intact oregano plants , P. This is the first time that such prolific bacterial growth inside the glands has been visually observed. Results of this study further revealed that several bacteria can be established on oregano leaves, suggesting that these bacteria have attributes that allow them to tolerate or benefit from oregano secondary metabolites. Micromorphology of trichomes of Thymus malyi Lamiaceae. Micromorphological, ultrastructural and morphometric investigations of the trichomes of Thymus malyi were carried out using a light microscope, a scanning electron microscope and a transmission electron microscope.
Unbranched non- glandular trichomes , peltate and capitate glandular trichomes were described. The leaves of Thymus malyi bear non- glandular and glandular trichomes on both sides. Estimates of the volume density i. Estimates of the number of these trichomes per area on sections showed that the capitate trichomes were the most abundant. Ultrastructural analyses of cell inner structure have shown numerous mitochondria, big nuclei and plastids with lipid globules and starch grains. Cotton Gossypium spp plants produce seed trichomes cotton fibers that are an important commodity worldwide; however, genes controlling cotton fiber development have not been characterized.
Here, we show that promoter of a cotton fiber gene, RDlike1 RDL1 , contains a homeodomain binding L1 box and a MYB binding motif that confer trichome -specific expression in Arabidopsis. We further demonstrate that the first intron of both GL1 and GaMYB2 plays a role in patterning trichomes : it acts as an enhancer in trichome and a repressor in nontrichome cells, generating a trichome -specific pattern of MYB gene expression. These results suggest that cotton and Arabidopsis use similar transcription factors for regulating trichomes and that GaMYB2 may be a key regulator of cotton fiber development.
Control of plant trichome development by a cotton fiber MYB gene. Trichoderma species form endophytic associations within Theobroma cacao trichomes. Trichoderma species are usually considered soil organisms that colonize plant roots, sometimes forming a symbiotic relationship. Recent studies demonstrate that Trichoderma species are also capable of colonizing the above ground tissues of Theobroma cacao cacao in what has been characterized as an endophytic relationship.
Trichoderma species can be re-isolated from surface sterilized cacao stem tissue, including the bark and xylem, the apical meristem, and to a lesser degree from leaves. The Trichoderma strains colonized the glandular trichome tips and formed swellings resembling appresoria. Hyphae were observed emerging from the glandular trichomes on surface sterilized stems from cacao seedlings that had been inoculated with each of the four Trichoderma strains.
Fungal hyphae were observed under the microscope emerging from the trichomes as soon as 6h after their isolation from surface sterilized cacao seedling stems. Hyphae were also observed, in some cases, emerging from stalk cells opposite the trichome head. Strains of four Trichoderma species were able to enter glandular trichomes during the colonization of cacao stems where they survived surface sterilization and could be re-isolated. The penetration of cacao trichomes may provide the entry point for Trichoderma species into the cacao stem allowing systemic colonization of this tissue.
Trichomes related to an unusual method of water retention and protection of the stem apex in an arid zone perennial species. It is well known that trichomes protect plant organs, and several studies have investigated their role in the adaptation of plants to harsh environments. Recent studies have shown that the production of hydrophilic substances by glandular trichomes and the deposition of this secretion on young organs may facilitate water retention, thus preventing desiccation and favouring organ growth until the plant develops other protective mechanisms.
This study sought to investigate trichomes and the origin of the substances observed on the stem apices of L. Samples of stem apices, young and expanded leaves were studied using standard techniques, including light microscopy and scanning and transmission electron microscopy. Histochemical tests were used to identify the major groups of metabolites present in the trichomes and the hyaline material deposited on the apices. Non- glandular trichomes and glandular trichomes were observed. The material deposited on the stem apices was hyaline, highly hydrophilic and viscous.
This hyaline material primarily consists of carbohydrates that result from the partial degradation of the cell wall of uniseriate trichomes. This degradation occurs at the same time that glandular trichomes secrete terpenoids, phenolic compounds and proteins. These results suggest that the non- glandular trichomes on the leaves of L. Furthermore, the secretion of glandular trichomes probably repels herbivore and pathogen attacks.
Artemisinin is highly effective against multidrug-resistant strains of Plasmodium falciparum, the aetiological agent of the most severe form of malaria. However, a low level of accumulation of artemisinin in Artemisia annua is a major limitation for its production and delivery to malaria endemic areas of the world. While several strategies to enhance artemisinin have been extensively explored, enhancing storage capacity in trichome has not yet been considered.
Transgene bgl1 integration and transcript were confirmed by molecular analysis. High-performance liquid chromatography, time of flight mass spectrometer data showed that artemisinin content increased up to 1. Artemisinin was enhanced up to five-fold in BGL1 transgenic flowers. This study opens the possibility of increasing artemisinin content by manipulating trichomes ' density, which is a major reservoir of artemisinin.
Combining biosynthetic pathway engineering with enhancing trichome density may further increase artemisinin yield in A. Because oral feeding of Artemisia plant cells reduced parasitemia more efficiently than the purified drug, reduced drug resistance and cost of prohibitively expensive purification process, enhanced expression should play a key role in making this valuable drug affordable to treat malaria in a large global population that disproportionally impacts low-socioeconomic areas and underprivileged children. Expression of Beta-glucosidase increases trichome density and artemisinin content in transgenic Artemisia annua plants.
Artemisinin is highly effective against multidrug-resistant strains of Plasmodium falciparum, the etiological agent of the most severe form of malaria. Transgene bgl1 integration and transcript was confirmed by molecular analysis. Artemisinin was enhanced up to 5-fold in BGL1 transgenic flowers. The present study opens the possibility of increasing artemisinin content by manipulating trichomes density, which is a major reservoir of artemisinin.
Flavonoids are a class of metabolites found in many plant species. They have been reported to serve several physiological roles, such as in defense against herbivores and pathogens and in protection against harmful ultraviolet radiation. They also serve as precursors of pigment compounds found in flowers, leaves, and seeds. Highly methylated, nonglycosylated derivatives of the flavonoid myricetin flavonoid, have been previously reported from a variety of plants , but O-methyltransferases responsible for their synthesis have not yet been identified.
Both genes are preferentially expressed in secreting glandular trichome types 1 and 4 and to a lesser degree in storage trichome type 6, and the levels of the proteins they encode are correspondingly higher in types 1 and 4 glands compared with type 6 glands. Helianthus annuus sunflower displays non- glandular trichomes NGT , capitate glandular trichomes CGT , and linear glandular trichomes LGT , which reveal different chemical compositions and locations in different plant tissues.
The results observed for sesquiterpenes and polymethoxylated flavones from LGT were similar. However, upon desiccation, LGT changed their shape in the ionization source, complicating analyses by MSI mainly after matrix application. The polymethoxylated flavones were easily ionized by LDI, producing images with higher resolution, but the sesquiterpenes were not observed in spectra.
Thus, the application and viability of MALDI imaging for the analyses of protein and secondary metabolites inside trichomes were confirmed, highlighting the importance of optimization parameters.
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The European wool-carder bee Anthidium manicatum eavesdrops on plant volatile organic compounds VOCs during trichome collection. The plant -pollinator relationship is generally considered mutualistic. This relationship is less clear, however, when pollinators also cause tissue damage. Some Megachilidae bees collect plant material for nests from the plants they pollinate.
In this study, we examined the relationship between Anthidium manicatum, the European wool-carder bee, and the source of its preferred nesting material - Stachys byzantina, lamb's ear. Female A. Using volatile organic compound VOC headspace analysis and behavioural observations, we explored a how carding effects S.
We found that removal of trichomes leads to a dissimilar VOC bouquet compared to intact leaves, with a significant increase in VOC detection following damage. Our data suggest that A. Accordingly, visitation by A. Trichomes , especially the capitate-stalked glandular hairs, are well known as the main sites of cannabinoid and essential oil production of Cannabis sativa. In this study the distribution and density of various types of Cannabis sativa L.
Furthermore, glandular trichomes were isolated over the flowering period 8 weeks by laser microdissection LMD and the cannabinoid profile analyzed by LCMS. Cannabinoids were detected in extracts of collected cells of capitate-sessile and capitate stalked trichomes and separately in the gland head and the stem of the latter.
Cannabichromene [CBC 8 ] along with cannabinol CBN 9 were identified as minor compounds only in the samples of intact capitate-stalked trichomes and their heads harvested from 8-week old plants. The hereby documented detection of metabolites in the stems of capitate-stalked trichomes indicates a complex biosynthesis and localization over the trichome cells forming the glandular secretion unit. Petunia hybrida PDR2 is involved in herbivore defense by controlling steroidal contents in trichomes.
As a first line of defense against insect herbivores many plants store high concentrations of toxic and deterrent secondary metabolites in glandular trichomes. Plant Pleiotropic Drug Resistance PDR -type ABC transporters are known secondary metabolite transporters, and several have been implicated in pathogen or herbivore defense.
Here, we report on Petunia hybrida PhPDR2 as a major contributor to trichome -related chemical defense. PhPDR2 was found to localize to the plasma membrane and be predominantly expressed in multicellular glandular trichomes of leaves and stems. Down-regulation of PhPDR2 via RNA interference pdr2 resulted in a markedly higher susceptibility of the transgenic plants to the generalist foliage feeder Spodoptera littoralis. Untargeted screening of pdr2 trichome metabolite contents showed a significant decrease in petuniasterone and petuniolide content, compounds, which had previously been shown to act as potent toxins against various insects.
Our findings suggest that PhPDR2 plays a leading role in controlling petuniasterone levels in leaves and trichomes of petunia, thus contributing to herbivory resistance. African violet genus "Saintpaulia" was identified as a particularly suitable genus for the study of specialised plant cells in the classroom using microscopes.
The techniques described here involve simple preparation without staining. The cells and structures that can be investigated include: trichomes hairs ; stomata; guard cells and…. Epifluorescence and stereomicroscopy of trichomes associated with resistant and susceptible host plant genotypes of the Asian citrus psyllid Hemiptera: Liviidae. Epifluorescence, light and stereo-microscopy were used to characterize foliar trichomes associated with young flush leaves and stems of six plant genotypes that are hosts of the Asian citrus psyllid, Diaphorina citri, vector of the economically important citrus greening disease.
These genotypes incl Phylogenic analyses revealed a close relationship between the tomato and Arabidopsis genes. On the other hand, GLSlGL3 transformation did not show any obvious effect on trichome or non-hair cell differentiation. These results suggest that tomato and Arabidopsis partially use similar transcription factors for epidermal cell differentiation, and that a CPC-like R3 MYB may be a key common regulator of plant trichome and root-hair development.
This enzyme is assembled from eight large subunits RbcL encoded by a single chloroplast gene and eight small subunits RbcS encoded by a nuclear gene family. Rubisco is primarily found in the chloroplasts of mesophyll C3 plants , bundle-sheath C4 plants , and guard cells. In certain species, photosynthesis also takes place in the secretory cells of glandular trichomes , which are epidermal outgrowths hairs involved in the secretion of specialized metabolites.
However, photosynthesis and, in particular, Rubisco have not been characterized in trichomes. Here, we show that tobacco Nicotiana tabacum trichomes contain a specific Rubisco small subunit, NtRbcS-T, which belongs to an uncharacterized phylogenetic cluster T.
This cluster contains RbcS from at least 33 species, including monocots, many of which are known to possess glandular trichomes. Cluster T is distinct from the cluster M, which includes the abundant, functionally characterized RbcS isoforms expressed in mesophyll or bundle-sheath cells. Expression of NtRbcS-T in Chlamydomonas reinhardtii and purification of the full Rubisco complex showed that this isoform conferred higher V max and K m values as well as higher acidic pH-dependent activity than NtRbcS-M, an isoform expressed in the mesophyll.
This observation was confirmed with trichome extracts. These data show that an ancient divergence allowed for the emergence of a so-far-uncharacterized RbcS cluster. We propose that secretory trichomes have a particular Rubisco uniquely adapted to secretory cells where CO 2 is released by the active specialized metabolism. All Rights Reserved. Trichome differentiation on leaf primordia of Helianthus annuus Asteraceae : morphology, gene expression and metabolite profile.
Sunflower trichomes fully develop on embryonic plumula within 3 days after start of germination. Toxic sesquiterpene lactones are produced immediately thereafter thus protecting the apical bud of the seedling against herbivory. Helianthus annuus harbors non- glandular and two different types of multicellular glandular trichomes , namely the biseriate capitate glandular trichomes and the uniseriate linear glandular trichomes. The development of capitate glandular trichomes is well known from anther tips on sunflower disk florets, but not from leaves and no information is yet available on the development of the linear glandular trichomes.
Scanning electron microscopy of sunflower seedlings unravelled that within the first 40 h of seed germination all three types of trichomes started to emerge on primordia of the first true leaves. Within the following h trichomes developed from trichoblasts to fully differentiated hairs. Gene expression studies showed that genes involved in the trichome -based sesquiterpene lactone formation were up-regulated between 72 and 96 h after start of germination. Metabolite profiling with HPLC confirmed the synthesis of sesquiterpene lactones which may contribute to protect the germinating seedlings from herbivory.
The study has shown that sunflower leaf primordia can serve as a fast and easy to handle model system for the investigation of trichome development in Asteraceae. A cold-tolerant evergreen interspecific hybrid of Ocimum kilimandscharicum and Ocimum basilicum: analyzing trichomes and molecular variations. Ocimum Lamiaceae is an important source of essential oils and aroma chemicals especially eugenol, methyl eugenol, linalool, methyl chavicol etc.
An elite evergreen hybrid has been developed from Ocimum kilimandscharicum and Ocimum basilicum, which demonstrated adaptive behavior towards cold stress. Ocimum genotypes were analyzed and compared for their trichome density. There were distinct differences on morphology, distribution, and structure between the two kinds of trichomes , i.
Testing of the remains proved inconclusive. This is consistent with allegations made in a report published on 30 June by Allan Nairn and Jean-Marie Simon that detainees "were being held at the headquarters of a security force called the Ambulant Military Police PMA outside the capital. The prisoners were held in cells hidden behind a concealed door in a building next to the soccer field.
Training courses included classes taught by civilians, including doctors, attorneys, and personal defense experts. From Wikipedia, the free encyclopedia. The captain cut the young man's throat and he made a terrifying noise, fell to the ground and blood poured out As cited in Jonathan L. Fried, Marvin E. Gettleman, Deborah T.
Levenson and Nancy Peckenham, eds.