The energy and reducing power from photosynthesis are used to support the biosynthesis of secondary metabolites, while the comparatively reduced Calvin-Benson-Bassham cycle activity may be involved in recycling metabolic CO2. Glandular trichomes cope with oxidative stress by producing high levels of polyunsaturated fatty acids, oxylipins, and glutathione.
Finally, distinct mechanisms are present in glandular trichomes to increase the supply of precursors for the isoprenoid pathways. Particularly, the citrate-malate shuttle supplies cytosolic acetyl-CoA and plastidic glycolysis and malic enzyme support the formation of plastidic pyruvate. A model is proposed on how glandular trichomes achieve high metabolic productivity.
Capitate glandular trichomes of Helianthus annuus Asteraceae : ultrastructure and cytological development. Previous studies have shown that capitate glandular trichomes CGT of the common sunflower, Helianthus annuus, produce sesquiterpene lactones STL and flavonoids, which are sequestered and accumulated between the apical cuticle and the wall of the tip cells. To explore the cellular structures required and putatively involved in the STL biosynthesis and secretion, the present study was focused on the development of CGT and the comparison of the ultrastructure of its different cell types.
Gradual maturation of flowers in the capitulum of the sunflower provided the possibility to study the simultaneous differentiation from the primordial to the secretory stage of CGT located by light microscopy bright field, differential interference contrast and fluorescence as well as transmission electron microscopy.
It was shown that the CGT of sunflower anthers had a biseriate structure with up to 14 cell pairs. In mature trichomes , the apical cells called secretory cells were covered entirely by a large cuticle globe, which enclosed the resinous terpenoids and was specialised in thickness and structure. The secretory cells lacked chloroplasts and contained mainly smooth endoplasmic reticulum sER. 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. 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. 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. Transmission electron microscopy indicates that metabolic products accumulate in vacuoles, the cytoplasm and intercellular spaces.
Estimates of the volume density i. Clients and shopkeepers mentioned a total of medicinal uses for a wide variety of ailments, of which the most frequent are visualized in Fig. The proportion of food- and non-food medicine was calculated afterwards. Identification of olivetolic acid cyclase from Cannabis sativa reveals a unique catalytic route to plant polyketides. Reiff, A. Pre-clinical nebuliser comparisons to allow more effective decision making on device selection.
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.