RESUMO
Trichomes are specialized epidermal outgrowths covering the aerial parts of most terrestrial plants. There is a large species variability in occurrence of different types of trichomes such that the molecular regulatory mechanism underlying the formation and the biological function of trichomes in most plant species remain unexplored. Here, we used Chrysanthemum morifolium as a model plant to explore the regulatory network in trichome formation and terpenoid synthesis and unravel the physical and chemical roles of trichomes in constitutive defense against herbivore feeding. By analyzing the trichome-related genes from transcriptome database of the trichomes-removed leaves and intact leaves, we identified CmMYC2 to positively regulate both development of T-shaped and glandular trichomes as well as the content of terpenoids stored in glandular trichomes. Furthermore, we found that the role of CmMYC2 in trichome formation and terpene synthesis was mediated by interaction with CmMYBML1. Our results reveal a sophisticated molecular mechanism wherein the CmMYC2-CmMYBML1 feedback inhibition loop regulates the formation of trichomes (non-glandular and glandular) and terpene biosynthesis, collectively contributing to the enhanced resistance to Spodoptera litura larvae feeding. Our findings provide new insights into the novel regulatory network by which the plant synchronously regulates trichome density for the physical and chemical defense against herbivory.
Assuntos
Chrysanthemum , Regulação da Expressão Gênica de Plantas , Herbivoria , Proteínas de Plantas , Terpenos , Tricomas , Tricomas/metabolismo , Terpenos/metabolismo , Chrysanthemum/genética , Chrysanthemum/metabolismo , Chrysanthemum/fisiologia , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Animais , Defesa das Plantas contra Herbivoria , Folhas de Planta/metabolismo , Genes de Plantas , Spodoptera/fisiologiaRESUMO
Rhus typhina is a valuable plant used in the pharmaceutical, cosmetic, and food industries due to the presence of biologically active substances accumulated in its organs, especially in secretory structures, i.e. trichomes and secretory ducts. Light microscopy, scanning electron microscopy, and transmission electron microscopy were used to examine the structure of glandular and non-glandular trichomes, as well as secretory ducts present in inflorescence peduncles of R. typhina. The chemical composition of the secretion produced by trichomes and ducts was assessed using histochemical techniques, including observations under brightfield and fluorescence microscopes. Two types of capitate glandular trichomes producing secretions with a similar composition and non-glandular trichomes exhibiting secretory activity were identified. The secretion of glandular trichomes was dominated by acidic and neutral lipids, essential oil, sesquiterpenes, and steroid-containing terpenes. The schizogenic secretory ducts located in the phloem produced a viscous milky substance with acidic polysaccharides, acidic lipids, phenolic compounds, and proteins. The secretion was released into the duct lumen through notches in the walls of the secretory epithelial cell facing the duct lumen. The location, type, and traits of the non-glandular trichomes and secretory structures, as well as the composition of the secreted products are considered important taxonomic features in the family Anacardiaceae and the Rhus genus. Additionally, these characters are important diagnostic markers for the pharmacobotanical identification of the species in medicinal and cosmetic raw materials. The various compounds present in the secretory structures of R. typhina may contribute to plant protection against pathogens or herbivory and probably play a role as attractants for pollinators and seed dispersers.
Assuntos
Rhus , Tricomas , Tricomas/ultraestrutura , Tricomas/metabolismo , Rhus/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Óleos Voláteis/química , HistocitoquímicaRESUMO
Trichomes are known to be important biofactories that contribute to the production of secondary metabolites, such as terpenoids. C2H2-zinc finger proteins (C2H2-ZFPs) are vital transcription factors of plants' trichome development. However, little is known about the function of Artemisia annua C2H2-ZFPs in trichome development. To explore the roles of this gene family in trichome development, two C2H2-ZFP transcription factors, named AaZFP8L and AaGIS3, were identified; both are hormonally regulated in A. annua. Overexpression of AaZFP8L in tobacco led to a significant increase in the density and length of glandular trichomes, and improved terpenoid content. In contrast, AaGIS3 was found to positively regulate non-glandular trichome initiation and elongation, which reduces terpenoid accumulation. In addition, ABA contents significantly increased in AaZFP8L-overexpressing tobacco lines and AaZFP8L also can directly bind the promoter of the ABA biosynthesis genes. This study lays the foundation for further investigating A. annua C2H2-ZFPs in trichome development and terpenoid accumulation.
Assuntos
Artemisia annua , Regulação da Expressão Gênica de Plantas , Nicotiana , Proteínas de Plantas , Fatores de Transcrição , Tricomas , Tricomas/metabolismo , Tricomas/crescimento & desenvolvimento , Tricomas/genética , Nicotiana/genética , Nicotiana/crescimento & desenvolvimento , Nicotiana/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Artemisia annua/genética , Artemisia annua/metabolismo , Artemisia annua/crescimento & desenvolvimento , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Plantas Geneticamente Modificadas , Terpenos/metabolismo , Ácido Abscísico/metabolismo , Regiões Promotoras Genéticas/genéticaRESUMO
The sesquiterpene lactone artemisinin is an important anti-malarial component produced by the glandular secretory trichomes of sweet wormwood (Artemisia annua L.). Light was previously shown to promote artemisinin production, but the underlying regulatory mechanism remains elusive. In this study, we demonstrate that ELONGATED HYPOCOTYL 5 (HY5), a central transcription factor in the light signaling pathway, cannot promote artemisinin biosynthesis on its own, as the binding of AaHY5 to the promoters of artemisinin biosynthetic genes failed to activate their transcription. Transcriptome analysis and yeast two-hybrid screening revealed the B-box transcription factor AaBBX21 as a potential interactor with AaHY5. AaBBX21 showed a trichome-specific expression pattern. Additionally, the AaBBX21-AaHY5 complex cooperatively activated transcription from the promoters of the downstream genes AaGSW1, AaMYB108, and AaORA, encoding positive regulators of artemisinin biosynthesis. Moreover, AaHY5 and AaBBX21 physically interacted with the A. annua E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). In the dark, AaCOP1 decreased the accumulation of AaHY5 and AaBBX21 and repressed the activation of genes downstream of the AaHY5-AaBBX21 complex, explaining the enhanced production of artemisinin upon light exposure. Our study provides insights into the central regulatory mechanism by which light governs terpenoid biosynthesis in the plant kingdom.
Assuntos
Artemisia annua , Artemisininas , Regulação da Expressão Gênica de Plantas , Luz , Proteínas de Plantas , Artemisininas/metabolismo , Artemisia annua/metabolismo , Artemisia annua/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Tricomas/metabolismo , Vias Biossintéticas/genéticaRESUMO
Previously, expression of the Arabidopsis thaliana GLABRA3 (GL3) induced trichome formation in Brassica napus. GL3 orthologues were examined from glabrous (B. oleracea), semi-glabrous (B. napus), moderately hirsute (B. rapa), and very hirsute (B. villosa) Brassica species. Ectopic expression of BnGL3, BrGL3 alleles, or BvGL3 induced trichome formation in glabrous B. napus with the effect on trichome number commensurate with density in the original accessions. Chimeric GL3 proteins in which the B. napus amino terminal region, which interacts with MYB proteins, or the middle region, which interacts with the WD40 protein TTG1, was exchanged with corresponding regions from A. thaliana were as stimulatory to trichome production as AtGL3. Exchange of the carboxy-terminal region containing a bHLH domain and an ACT domain did not alter the trichome stimulatory activity, although modeling of the ACT domain identified differences that could affect GL3 dimerization. B. napus A- and C-genomes orthologues differed in their abilities to form homo- and heterodimers. Modeling of the amino-terminal region revealed a conserved domain that may represent the MYB factor binding pocket. This region interacted with the MYB factors GL1, CPC, and TRY, as well as with JAZ8, which is involved in jasmonic acid-mediated regulation of MYC-like transcription factors. Protein interaction studies indicated that GL1 interaction with GL3 from B. napus and A. thaliana may underlie the difference in their respective abilities to induce trichome formation.
Assuntos
Proteínas de Arabidopsis , Brassica napus , Proteínas de Plantas , Tricomas , Brassica napus/genética , Brassica napus/metabolismo , Tricomas/metabolismo , Tricomas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Plantas Geneticamente Modificadas , Fatores de Transcrição Hélice-Alça-Hélice BásicosRESUMO
Trichomes are specialized epidermal structures that protect plants from biotic and abiotic stresses by synthesizing, storing, and secreting defensive compounds. This study investigates the role of the Gossypium arboreum DNA topoisomerase VI subunit B gene (GaTOP6B) in trichome development and branching. Sequence alignment revealed a high similarity between GaTOP6B and AtTOP6B, suggesting a conserved function in trichome regulation. Although AtTOP6B acts as a positive regulator of trichome development, functional analyses showed contrasting effects: Virus-induced gene silencing (VIGS) of GaTOP6B in cotton increased trichome density, while its overexpression in Arabidopsis decreased trichome density but enhanced branching. This demonstrates that GaTOP6B negatively regulates trichome number, indicating species-specific roles in trichome initiation and branching between cotton and Arabidopsis. Overexpression of the GaTOP6B promotes jasmonic acid synthesis, which in turn inhibits the G1/S or G2/M transitions, stalling the cell cycle. On the other hand, it suppresses brassinolide synthesis and signaling while promoting cytokinin degradation, further inhibiting mitosis. These hormonal interactions facilitate the transition of cells from the mitotic cycle to the endoreduplication cycle. As the level of endoreduplication increases, trichomes develop an increased number of branches. These findings highlight GaTOP6B's critical role as a regulator of trichome development, providing new genetic targets for improving cotton varieties in terms of enhanced adaptability and resilience.
Assuntos
Arabidopsis , Ciclopentanos , Endorreduplicação , Regulação da Expressão Gênica de Plantas , Gossypium , Oxilipinas , Proteínas de Plantas , Tricomas , Tricomas/genética , Tricomas/crescimento & desenvolvimento , Tricomas/metabolismo , Gossypium/genética , Gossypium/crescimento & desenvolvimento , Gossypium/metabolismo , Ciclopentanos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Oxilipinas/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Endorreduplicação/genética , Brassinosteroides/metabolismo , Plantas Geneticamente Modificadas , Genes de Plantas , DNA Topoisomerases Tipo II/genética , DNA Topoisomerases Tipo II/metabolismo , Esteroides HeterocíclicosAssuntos
Solanum , Açúcares , Tricomas , Solanum/metabolismo , Tricomas/metabolismo , Açúcares/metabolismoRESUMO
BACKGROUND: The glandular trichomes of tobacco (Nicotiana tabacum) can efficiently produce secondary metabolites. They act as natural bioreactors, and their natural products function to protect plants against insect-pests and pathogens and are also components of industrial chemicals. To clarify the molecular mechanisms of tobacco glandular trichome development and secondary metabolic regulation, glandular trichomes and glandless trichomes, as well as other different developmental tissues, were used for RNA sequencing and analysis. RESULTS: By comparing glandless and glandular trichomes with other tissues, we obtained differentially expressed genes. They were obviously enriched in KEGG pathways, such as cutin, suberine, and wax biosynthesis, flavonoid and isoflavonoid biosynthesis, terpenoid biosynthesis, and plant-pathogen interaction. In particular, the expression levels of genes related to the terpenoid, flavonoid, and wax biosynthesis pathway mainly showed down-regulation in glandless trichomes, implying that they lack the capability to synthesize certain exudate compounds. Among the differentially expressed genes, 234 transcription factors were found, including AP2-ERFs, MYBs, bHLHs, WRKYs, Homeoboxes (HD-ZIP), and C2H2-ZFs. These transcription factor and genes that highly expressed in trichomes or specially expressed in GT or GLT. Following the overexpression of R2R3-MYB transcription factor Nitab4.5_0011760g0030.1 in tobacco, an increase in the number of branched glandular trichomes was observed. CONCLUSIONS: Our data provide comprehensive gene expression information at the transcriptional level and an understanding of the regulatory pathways involved in glandular trichome development and secondary metabolism.
Assuntos
Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Nicotiana , Tricomas , Tricomas/genética , Tricomas/metabolismo , Tricomas/crescimento & desenvolvimento , Nicotiana/genética , Nicotiana/metabolismo , Nicotiana/crescimento & desenvolvimento , Transcriptoma , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Genes de Plantas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Tea trichomes were regarded as an essential evaluation index for reflecting tea flavor quality in terms of aroma and influence on infusion color. This study reveals the impact of golden oxidized trichomes on the color, volatile and non-volatile metabolites of black teas through comparative metabolomics combined quantitative analysis on hongbiluo (trichomes-deficiency black teas), hongjinluo (trichomes-rich black teas), and trichomes (from hongjinluo). Forty-six volatile components were detected using headspace solid-phase microextraction gas chromatography-mass spectrometry, while the results suggested that the contribution of trichomes to black teas is limited. A total of 60 marker non-volatile compounds were identified, including catechins, catechin oxidation products, flavonoid glycosides, organic acids, hydrolysable tannins and amino acids. Notably, p-coumaroyl-kaempferol glucosides, and catechin dimers demonstrated high levels in independent trichomes and showed a positive correlation with the brightness and yellow hue of black tea infusions, specifically kaempferol 3-O-di-(p-coumaroyl)-hexoside. Furthermore, results from fractional extraction analysis of separated trichomes provided that N-ethyl-2-pyrrolidinone-substituted epicatechin gallates, acylated kaempferol glycosides, and chromogenic catechins dimers, such as theaflavins, were primary color contributors in oxidized trichomes. Especially, we found that epicatechin gallate (ECG) and its derivates, 3'-O-methyl-ECG and N-ethyl-2-pyrrolidinone-substituted ECG, highly accumulated in trichomes, which may be associated with the varieties of hongbiluo and hongjinluo black teas. Eventually, addition tests were applied to verify the color contribution of trichome mixtures. Our findings employed comprehensive information revealing that golden oxidized trichomes contributed significantly to the brightness and yellow hue of black tea infusion, but their contribution to the aroma and metabolic profile is limited. These findings may contribute to the effective modulation of the infusion color during black tea production by regulating the proportion of tea trichomes or screening trichomes-rich or deficiency varieties.
Assuntos
Camellia sinensis , Cor , Cromatografia Gasosa-Espectrometria de Massas , Metabolômica , Oxirredução , Chá , Tricomas , Compostos Orgânicos Voláteis , Metabolômica/métodos , Chá/química , Camellia sinensis/química , Compostos Orgânicos Voláteis/análise , Tricomas/química , Tricomas/metabolismo , Catequina/análise , Catequina/análogos & derivados , Catequina/metabolismo , Microextração em Fase Sólida , Folhas de Planta/química , Metaboloma , Flavonoides/análiseRESUMO
Species in the genus Utricularia are carnivorous plants that prey on invertebrates using traps of leaf origin. The traps are equipped with numerous different glandular trichomes. Trichomes (quadrifids) produce digestive enzymes and absorb the products of prey digestion. The main aim of this study was to determine whether arabinogalactan proteins (AGPs) occur in the cell wall ingrowths in the quadrifid cells. Antibodies (JIM8, JIM13, JIM14, MAC207, and JIM4) that act against various groups of AGPs were used. AGP localization was determined using immunohistochemistry techniques and immunogold labeling. AGPs localized with the JIM13, JIM8, and JIM14 epitopes occurred in wall ingrowths of the pedestal cell, which may be related to the fact that AGPs regulate the formation of wall ingrowths but also, due to the patterning of the cell wall structure, affect symplastic transport. The presence of AGPs in the cell wall of terminal cells may be related to the presence of wall ingrowths, but processes also involve vesicle trafficking and membrane recycling, in which these proteins participate.
Assuntos
Parede Celular , Mucoproteínas , Proteínas de Plantas , Mucoproteínas/metabolismo , Proteínas de Plantas/metabolismo , Parede Celular/metabolismo , Tricomas/metabolismo , Folhas de Planta/metabolismo , Lamiales/metabolismoRESUMO
Artemisia argyi is an herbaceous plant of the genus Artemisia. Its young and mature leaves are used as food and medicine, respectively. Glandular trichomes (GTs) are distributed on the leaf surface in A. argyi and are generally considered the location of flavonoid biosynthesis and accumulation. However, the mechanism of flavonoid biosynthesis and accumulation in A. argyi remains unclear. In this study, the coregulatory genes involved in flavonoid biosynthesis and trichome development in this species were screened and evaluated, and the biosynthetic pathways for key flavonoids in A. argyi were uncovered. AaMYB1 and AaYABBY1 were screened using weighted gene co-expression network analysis, and both genes were then genetically transformed into Nicotiana tabacum L. cv. K326 (tobacco). Simultaneously, AaYABBY1 was also genetically transformed into Arabidopsis thaliana. The total flavonoid and rutin contents were increased in tobacco plants overexpressing AaMYB1 and AaYABBY1, and the expression levels of genes participating in the flavonoid synthesis pathway, such as PAL, FLS, and F3H, were significantly up-regulated in plants overexpressing these genes. These results indicated that AaMYB1 and AaYABBY1 promote flavonoid biosynthesis in tobacco. Furthermore, compared to that in the wild-type, the trichome density was significantly increased in tobacco and A. thaliana plants overexpressing AaYABBY1. These results confirm that AaYABBY1 might be involved in regulating trichome formation in A. argyi. This indicates the potential genes involved in and provides new insights into the development of trichome cellular factories based on the "development-metabolism" interaction network and the cultivation of high-quality A. argyi.
Assuntos
Artemisia , Flavonoides , Regulação da Expressão Gênica de Plantas , Nicotiana , Tricomas , Artemisia/genética , Artemisia/metabolismo , Artemisia/crescimento & desenvolvimento , Tricomas/metabolismo , Tricomas/genética , Tricomas/crescimento & desenvolvimento , Flavonoides/biossíntese , Flavonoides/metabolismo , Nicotiana/genética , Nicotiana/metabolismo , Nicotiana/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/genética , Genes de Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Vias Biossintéticas/genética , MultiômicaRESUMO
Solanaceae (nightshade family) species synthesize a remarkable array of clade- and tissue-specific specialized metabolites. Protective acylsugars, one such class of structurally diverse metabolites, are produced by ACYLSUGAR ACYLTRANSFERASE (ASAT) enzymes from sugars and acyl-coenzyme A esters. Published research has revealed trichome acylsugars composed of glucose and sucrose cores in species across the family. In addition, acylsugars have been analyzed across a small fraction of the >1,200 species in the phenotypically megadiverse Solanum genus, with a handful containing inositol and glycosylated inositol cores. The current study sampled several dozen species across subclades of Solanum to get a more detailed view of acylsugar chemodiversity. In depth characterization of acylsugars from the clade II species brinjal eggplant (Solanum melongena) led to the identification of eight unusual structures with inositol or inositol glycoside cores and hydroxyacyl chains. Liquid chromatography-mass spectrometry analysis of 31 additional species in the Solanum genus revealed striking acylsugar diversity, with some traits restricted to specific clades and species. Acylinositols and inositol-based acyldisaccharides were detected throughout much of the genus. In contrast, acylglucoses and acylsucroses were more restricted in distribution. Analysis of tissue-specific transcriptomes and interspecific acylsugar acetylation differences led to the identification of the brinjal eggplant ASAT 3-LIKE 1 (SmASAT3-L1; SMEL4.1_12g015780) enzyme. This enzyme is distinct from previously characterized acylsugar acetyltransferases, which are in the ASAT4 clade, and appears to be a functionally divergent ASAT3. This study provides a foundation for investigating the evolution and function of diverse Solanum acylsugar structures and harnessing this diversity in breeding and synthetic biology.
Assuntos
Solanum , Tricomas , Solanum/genética , Solanum/metabolismo , Tricomas/metabolismo , Tricomas/genética , Inositol/metabolismo , Aciltransferases/metabolismo , Aciltransferases/genética , Filogenia , Açúcares/metabolismoRESUMO
With a continuous increase in world population and food production, chemical pesticide use is growing accordingly, yet unsustainably. As chemical pesticides are harmful to the environment and developmental resistance in pests is increasing, a sustainable and effective pesticide alternative is needed. Inspired by nature, we mimic one defense strategy of plants, glandular trichomes, to shift away from using chemical pesticides by moving toward a physical immobilization strategy via adhesive particles. Through controlled oxidation of a biobased starting material, triglyceride oils, an adhesive material is created while monitoring the reactive intermediates. After being milled into particles, nanoindentation shows these particles to be adhesive even at low contact forces. A suspension of particles is then sprayed and found to be effective at immobilizing a target pest, thrips, Frankliniella occidentalis. Small arthropod pests, like thrips, can cause crop damage through virus transfer, which is prevented by their immobilization. We show that through a scalable fabrication process, biosourced materials can be used to create an effective, sustainable physical pesticide.
Assuntos
Adesivos , Adesivos/química , Animais , Tisanópteros/fisiologia , Praguicidas/química , Praguicidas/farmacologia , Tricomas/metabolismoRESUMO
BACKGROUND: Zataria multiflora Boiss. is a medicinal and aromatic plant from the Lamiaceae family. It is extensively used in Iranian traditional medicine, mostly as a replacement for Thyme species. This study was focused on the analysis of chemical composition and the distribution and types of trichomes of Z. multiflora grown under different conditions. Equilibrium headspace analysis in combination with GC-FID-MS was used to identify volatile compounds released by aerial parts of Z. multiflora in development stages of 50 and 100% flowering under normal and drought-stress conditions. RESULTS: The main constituents were p-cymene (20.06-27.40%), γ-terpinene (12.44-16.93%), and α-pinene (6.91-16.58%) and thymol (8.52-9.99%). The highest content of p-cymene (27.40%) and thymol (9.99%) was observed in the 50% flowering stage at the 90% field capacity, while the maximum γ-terpinene (16.93%) content was recorded in the 100% flowering stage under normal conditions. Using the SEM method, it was found that peltate glandular and non-glandular trichomes are distributed on the surface of the leaf, stem, and outer side of the calyx. However, capitate trichomes only are detected on the stem and calyx in the 100% flowering and beginning of blooming stages, respectively. The type and structure of trichomes do not vary in different development stages, but they differ in density. The highest number of leaf peltate glandular trichomes was observed in the vegetative and beginning of blooming stages at 50% and 90% field capacity, respectively. Non-glandular trichomes of the stem were observed with high density in both normal and stress conditions, which are more densely in 90% field capacity. CONCLUSIONS: Since this plant has strong potential to be used in the food and pharmacological industries, this study provides valuable information for its cultivation and harvesting at specific phenological stages, depending on desired compounds and their concentrations.
Assuntos
Lamiaceae , Tricomas , Tricomas/crescimento & desenvolvimento , Tricomas/metabolismo , Lamiaceae/crescimento & desenvolvimento , Lamiaceae/metabolismo , Lamiaceae/fisiologia , Lamiaceae/química , Secas , Compostos Orgânicos Voláteis/metabolismo , Compostos Orgânicos Voláteis/análise , Estresse Fisiológico , Monoterpenos Cicloexânicos/metabolismo , Cimenos/metabolismo , Monoterpenos/metabolismo , Monoterpenos Bicíclicos/metabolismo , Timol/metabolismoRESUMO
Flowers of Cannabis sativa L. are densely covered with glandular trichomes containing cannabis resin that is used for medicinal and recreational purposes. The highly productive glandular trichomes have been described as 'biofactories.' In this review, we use this analogy to highlight recent advances in cannabis cell biology, metabolomics, and transcriptomics. The biofactory is built by epidermal outgrowths that differentiate into peltate-like glandular trichome heads, consisting of a disc of interconnected secretory cells with unique cellular structures. Cannabinoid and terpenoid products are warehoused in the extracellular storage cavity. Finally, multicellular stalks raise the glandular heads above the epidermis, giving cannabis flower their frosty appearance.
Assuntos
Cannabis , Tricomas , Cannabis/metabolismo , Tricomas/metabolismo , Flores/metabolismo , Flores/genética , Canabinoides/metabolismo , Terpenos/metabolismoRESUMO
Salt stress is one of the main abiotic factor affecting plant growth. We have previously identified a key gene (NtHD9) in Nicotiana tabacum L. that positively regulates the formation of long glandular trichomes (LGTs). Here, we verified that both abiotic stress (aphids, drought and salt stress) could restore the phenotype lacking LGTs in NtHD9-knockout (NtHD9-KO) plants. The abiotic stress response assays indicated that NtHD9 is highly sensitive to salt stress. Compared with cultivated tobacco "K326" (CK) plants, NtHD9-overexpressing (NtHD9-OE) plants with more LGTs exhibited stronger salt tolerance, whereas NtHD9-KO with no LGTs showed weaker tolerance to salt. The densities and sizes of the glandular heads gradually increased with increasing NaCl concentrations in NtHD9-KO plants. Mineral element determination showed that leaves and trichomes of NtHD9-OE plants accumulated less Na+ but had higher K+ contents under salt stress, thus maintaining ion homeostasis in plants, which could contribute to a robust photosynthetic and antioxidant system under salt stress. Therefore, NtHD9-OE plants maintained a larger leaf area and root length under high-salt conditions than CK and NtHD9-KO plants. We verified that NtHD9 could individually interact with NtHD5, NtHD7, NtHD12, and NtJAZ10 proteins. Salt stress led to an increase in jasmonic acid (JA) levels and activated the expression of NtHDs while inhibiting the expression of NtJAZ. This study suggests that the glandular heads play an important role in plant resistance to salt stress. The activation of JA signaling leading to JAZ protein degradation may be key factors regulating the glandular heads development under salt stress.
Assuntos
Nicotiana , Proteínas de Plantas , Tolerância ao Sal , Tricomas , Nicotiana/genética , Nicotiana/metabolismo , Nicotiana/fisiologia , Tricomas/metabolismo , Tricomas/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Tolerância ao Sal/genética , Regulação da Expressão Gênica de Plantas , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/genética , Plantas Geneticamente ModificadasRESUMO
Cembranoids and labdanes are two important types of diterpenes in tobacco (Nicotiana genus) that are predominantly found in the leaf and flower glandular trichome secretions. This is the first systematic review of the biosynthesis, chemical structures, bioactivities, and utilisation values of cembranoid and labdane diterpenes in tobacco. A total of 131 natural cembranoid diterpenes have been reported in tobacco since 1962; these were summarised and classified according to their chemical structure characteristics as isopropyl cembranoids (1-88), seco-cembranoids (89-103), chain cembranoids (104-123), and polycyclic cembranoids (124-131). Forty natural labdane diterpenes reported since 1961 were also summarised and divided into epoxy side chain labdanes (132-150) and epoxy-free side chain labdanes (151-171). Tobacco cembranoid and labdane diterpenes are both formed via the methylerythritol 4-phosphate pathway and are synthesised from geranylgeranyl diphosphate. Their biosynthetic pathways and the four key enzymes (cembratrienol synthase, cytochrome P450 hydroxylase, copalyl diphosphate synthase, and Z-abienol cyclase) that affect their biosynthesis have been described in detail. A systematic summary of the bioactivity and utilisation values of the cembranoid and labdane diterpenes is also provided. The agricultural bioactivities associated with cembranoid and labdane diterpenes include antimicrobial and insecticidal activities as well as induced resistance, while the medical bioactivities include cytotoxic and neuroprotective activities. Further research into the cembranoid and labdane diterpenes will help to promote their development and utilisation as plant-derived pesticides and medicines.
Assuntos
Diterpenos , Nicotiana , Tricomas , Diterpenos/química , Diterpenos/farmacologia , Diterpenos/metabolismo , Tricomas/química , Tricomas/metabolismo , Nicotiana/química , Estrutura Molecular , HumanosRESUMO
The essential oil of Pelargonium graveolens (rose-scented geranium), an important aromatic plant, comprising mainly mono- and sesqui-terpenes, has applications in food and cosmetic industries. This study reports the characterization of isoprenyl disphosphate synthases (IDSs) involved in P. graveolens terpene biosynthesis. The six identified PgIDSs belonged to different classes of IDSs, comprising homomeric geranyl diphosphate synthases (GPPSs; PgGPPS1 and PgGPPS2), the large subunit of heteromeric GPPS or geranylgeranyl diphosphate synthases (GGPPSs; PgGGPPS), the small subunit of heteromeric GPPS (PgGPPS.SSUI and PgGPPS.SSUII), and farnesyl diphosphate synthases (FPPS; PgFPPS).All IDSs exhibited maximal expression in glandular trichomes (GTs), the site of aroma formation, and their expression except PgGPPS.SSUII was induced upon treatment with MeJA. Functional characterization of recombinant proteins revealed that PgGPPS1, PgGGPPS and PgFPPS were active enzymes producing GPP, GGPP/GPP, and FPP respectively, whereas both PgGPPS.SSUs and PgGPPS2 were inactive. Co-expression of PgGGPPS (that exhibited bifunctional G(G)PPS activity) with PgGPPS.SSUs in bacterial expression system showed lack of interaction between the two proteins, however, PgGGPPS interacted with a phylogenetically distant Antirrhinum majus GPPS.SSU. Further, transient expression of AmGPPS.SSU in P. graveolens leaf led to a significant increase in monoterpene levels. These findings provide insight into the types of IDSs and their role in providing precursors for different terpenoid components of P. graveolens essential oil.
Assuntos
Pelargonium , Proteínas de Plantas , Terpenos , Terpenos/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Pelargonium/metabolismo , Pelargonium/genética , Alquil e Aril Transferases/metabolismo , Alquil e Aril Transferases/genética , Regulação da Expressão Gênica de Plantas , Filogenia , Tricomas/metabolismo , Óleos Voláteis/metabolismoRESUMO
The TTG2 transcription factor of Arabidopsis regulates a set of epidermal traits, including the differentiation of leaf trichomes, flavonoid pigment production in cells of the inner testa (or seed coat) layer and mucilage production in specialized cells of the outer testa layer. Despite the fact that TTG2 has been known for over twenty years as an important regulator of multiple developmental pathways, little has been discovered about the downstream mechanisms by which TTG2 co-regulates these epidermal features. In this study, we present evidence of phosphoinositide lipid signaling as a mechanism for the regulation of TTG2-dependent epidermal pathways. Overexpression of the AtPLC1 gene rescues the trichome and seed coat phenotypes of the ttg2-1 mutant plant. Moreover, in the case of seed coat color rescue, AtPLC1 overexpression restored expression of the TTG2 flavonoid pathway target genes, TT12 and TT13/AHA10. Consistent with these observations, a dominant AtPLC1 T-DNA insertion allele (plc1-1D) promotes trichome development in both wild-type and ttg2-3 plants. Also, AtPLC1 promoter:GUS analysis shows expression in trichomes and this expression appears dependent on TTG2. Taken together, the discovery of a genetic interaction between TTG2 and AtPLC1 suggests a role for phosphoinositide signaling in the regulation of trichome development, flavonoid pigment biosynthesis and the differentiation of mucilage-producing cells of the seed coat. This finding provides new avenues for future research at the intersection of the TTG2-dependent developmental pathways and the numerous molecular and cellular phenomena influenced by phospholipid signaling.