Micromorphological variations of trichomes in the genus Ocimum L.

Ocimum L. is an attractive fragrant ornamental plant with medicinal aromatic compounds. The study using digital microscopy revealed the distinct epidermal trichome morphology in five species of Ocimum including O. americanum L., O. basilicum L., O. gratissimum L., O. kilimandscharicum Gurke and O. tenuiflorum L. A distinguished variation in size, shape, type and abundance of trichomes on leaves and stem of all species are described and photographed. Both glandular and non-glandular trichomes scrutinized in all the species in which glandular type comprised capitate and peltate trichomes. On the stem, the longest glandular capitate trichome (GCT) and non-glandular trichome (NGT) were observed in O. tenuiflorum while O. basilicum possessed longest glandular peltate trichome (GPT). In case of foliar trichomes, the longest GCT observed on leaves of O. americanum; and O. basilicum showed the longest GPT and NGT. In the species, the septate or aseptate NGT possessed uni, bi or multicellular base with acute or broad apex. A distinguished variation in the number of cells in stalk and head of GT was observed in the study. Presence of silica bodies in peltate trichome of O. kilimandscharicum was noticed as the characteristic feature. Among the five species, the trichomes were abundant in O. kilimandscharicum; while O. basilicum showed sparse distribution. Trichomes with disrupted cells were also noted in O. americanum. Due to the presence of specific trichome characteristics, the efficient taxonomic key is prepared to identify the taxa at species level.

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Trichome micromorphology of the Chinese-Himalayan genus Colquhounia (Lamiaceae), with emphasis on taxonomic implications

Biologia ◽

10.2478/s11756-012-0076-z ◽

2012 ◽

Vol 67 (5) ◽

Cited By ~ 11

Author(s):

Guo-Xiong Hu ◽

Teodora Balangcod ◽

Chun-Lei Xiang

Keyword(s):

Glandular Trichomes ◽

Morphological Diversity ◽

Species Relationships ◽

Key To Species ◽

Infrageneric Classification ◽

C Elegans ◽

Taxonomic Implications ◽

Trichome Morphology ◽

Insight Into ◽

Number Of Cells

AbstractTrichome micromorphology of leaves and young stems of nine taxa (including four varieties) of Colquhounia were examined using light and scanning microscopy. Two basic types of trichomes were recognized: eglandular and glandular. Eglandular trichomes are subdivided into simple and branched trichomes. Based on the number of cells and trichome configuration, simple eglandular trichomes are further divided into four forms: unicellular, two-celled, three-celled and more than three-celled trichomes. Based on branching configuration, the branched eglandular trichomes can be separated into three forms: biramous, stellate and dendroid. Glandular trichomes can be divided into two subtypes: capitate and peltate glandular trichomes. Results from this study of morphological diversity of trichomes within Colquhounia lend insight into infrageneric classification and species relationships. Based on the presence of branched trichomes in C. elegans, this species should be transferred from Colquhounia sect. Simplicipili to sect. Colquhounia. We provide a taxonomic key to species of Chinese Colquhounia based on trichome morphology and other important morphological traits.

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A novel non-trichome based whitefly resistance QTL in Solanum galapagense

Euphytica ◽

10.1007/s10681-021-02770-7 ◽

2021 ◽

Vol 217 (3) ◽

Author(s):

Joris Santegoets ◽

Marcella Bovio ◽

Wendy van’t Westende ◽

Roeland E. Voorrips ◽

Ben Vosman

Keyword(s):

Frankliniella Occidentalis ◽

Recombinant Inbred Lines ◽

Glandular Trichomes ◽

Glandular Trichome ◽

Trialeurodes Vaporariorum ◽

Inbred Lines ◽

Adult Survival ◽

Greenhouse Whitefly ◽

Major Threat ◽

Type Iv

AbstractThe greenhouse whitefly Trialeurodes vaporariorum is a major threat in tomato cultivation. In greenhouse grown tomatoes non-trichome based whitefly resistance may be better suited than glandular trichome based resistance as glandular trichomes may interfere with biocontrol, which is widely used. Analysis of a collection of recombinant inbred lines derived from a cross between Solanum lycopersicum and Solanum galapagense showed resistance to the whitefly T. vaporariorum on plants without glandular trichomes type IV. The resistance affected whitefly adult survival (AS), but not oviposition rate. This indicates that S. galapagense, in addition to trichome based resistance, also carries non-trichome based resistance components. The effectiveness of the non-trichome based resistance appeared to depend on the season in which the plants were grown. The resistance also had a small but significant effect on the whitefly Bemisia tabaci, but not on the thrips Frankliniella occidentalis. A segregating F2 population was created to map the non-trichome based resistance. Two Quantitative trait loci (QTLs) for reduced AS of T. vaporariorum were mapped on chromosomes 12 and 7 (explaining 13.9% and 6.0% of the variance respectively). The QTL on chromosome 12 was validated in F3 lines.

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Introgression of the sesquiterpene biosynthesis from Solanum habrochaites to cultivated tomato offers insights into trichome morphology and arthropod resistance

Planta ◽

10.1007/s00425-021-03651-y ◽

2021 ◽

Vol 254 (1) ◽

Author(s):

Rodrigo Therezan ◽

Ruy Kortbeek ◽

Eloisa Vendemiatti ◽

Saioa Legarrea ◽

Severino M. de Alencar ◽

...

Keyword(s):

Glandular Trichomes ◽

Pest Resistance ◽

Chromosome 8 ◽

Cavity Size ◽

Solanum Habrochaites ◽

Genetic Components ◽

Internal Storage ◽

In The Wild ◽

Low Levels ◽

Trichome Morphology

Abstract Main conclusion Cultivated tomatoes harboring the plastid-derived sesquiterpenes from S. habrochaites have altered type-VI trichome morphology and unveil additional genetic components necessary for piercing-sucking pest resistance. Abstract Arthropod resistance in the tomato wild relative Solanum habrochaites LA1777 is linked to specific sesquiterpene biosynthesis. The Sesquiterpene synthase 2 (SsT2) gene cluster on LA1777 chromosome 8 controls plastid-derived sesquiterpene synthesis. The main genes at SsT2 are Z-prenyltransferase (zFPS) and Santalene and Bergamotene Synthase (SBS), which produce α-santalene, β-bergamotene, and α-bergamotene in LA1777 round-shaped type-VI glandular trichomes. Cultivated tomatoes have mushroom-shaped type-VI trichomes with much smaller glands that contain low levels of monoterpenes and cytosolic-derived sesquiterpenes, not presenting the same pest resistance as in LA1777. We successfully transferred zFPS and SBS from LA1777 to cultivated tomato (cv. Micro-Tom, MT) by a backcrossing approach. The trichomes of the MT-Sst2 introgressed line produced high levels of the plastid-derived sesquiterpenes. The type-VI trichome internal storage-cavity size increased in MT-Sst2, probably as an effect of the increased amount of sesquiterpenes, although it was not enough to mimic the round-shaped LA1777 trichomes. The presence of high amounts of plastid-derived sesquiterpenes was also not sufficient to confer resistance to various tomato piercing-sucking pests, indicating that the effect of the sesquiterpenes found in the wild S. habrochaites can be insect specific. Our results provide for a better understanding of the morphology of S. habrochaites type-VI trichomes and paves the way to obtain insect-resistant tomatoes.

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Transcriptome Analysis of Light-Regulated Monoterpenes Biosynthesis in Leaves of Mentha canadensis L.

Plants ◽

10.3390/plants10050930 ◽

2021 ◽

Vol 10 (5) ◽

pp. 930

Author(s):

Xu Yu ◽

Xiwu Qi ◽

Shumin Li ◽

Hailing Fang ◽

Yang Bai ◽

...

Keyword(s):

Essential Oil ◽

Transcriptome Analysis ◽

Average Length ◽

Glandular Trichomes ◽

Signal Transduction Pathway ◽

Glandular Trichome ◽

Light Treatment ◽

Light Signal ◽

Environmental Aspect ◽

Underlying Mechanisms

Light is a key environmental aspect that regulates secondary metabolic synthesis. The essential oil produced in mint (Mentha canadensis L.) leaves is used widely in the aromatics industry and in medicine. Under low-light treatment, significant reductions in peltate glandular trichome densities were observed. GC-MS analysis showed dramatically reduced essential oil and menthol contents. Light affected the peltate glandular trichomes’ development and essential oil yield production. However, the underlying mechanisms of this regulation were elusive. To identify the critical genes during light-regulated changes in oil content, following a 24 h darkness treatment and a 24 h recovery light treatment, leaves were collected for transcriptome analysis. A total of 95,579 unigenes were obtained, with an average length of 754 bp. About 56.58% of the unigenes were annotated using four public protein databases: 10,977 differentially expressed genes (DEGs) were found to be involved in the light signaling pathway and monoterpene synthesis pathway. Most of the TPs showed a similar expression pattern: downregulation after darkness treatment and upregulation after the return of light. In addition, the genes involved in the light signal transduction pathway were analyzed. A series of responsive transcription factors (TFs) were identified and could be used in metabolic engineering as an effective strategy for increasing essential oil yields.

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Single Wavelengths of LED Light Supplement Promote the Biosynthesis of Major Cyclic Monoterpenes in Japanese Mint

Plants ◽

10.3390/plants10071420 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1420

Author(s):

Takahiro Ueda ◽

Miki Murata ◽

Ken Yokawa

Keyword(s):

Blue Light ◽

Solid Phase ◽

Glandular Trichomes ◽

Red Light ◽

Glandular Trichome ◽

Pulse Amplitude ◽

Light Treatment ◽

Led Light ◽

Trichome Formation ◽

Japanese Mint

Environmental light conditions influence the biosynthesis of monoterpenes in the mint plant. Cyclic terpenes, such as menthol, menthone, pulegone, and menthofuran, are major odor components synthesized in mint leaves. However, it is unclear how light for cultivation affects the contents of these compounds. Artificial lighting using light-emitting diodes (LEDs) for plant cultivation has the advantage of preferential wavelength control. Here, we monitored monoterpene contents in hydroponically cultivated Japanese mint leaves under blue, red, or far-red wavelengths of LED light supplements. Volatile cyclic monoterpenes, pulegone, menthone, menthol, and menthofuran were quantified using the head-space solid phase microextraction method. As a result, all light wavelengths promoted the biosynthesis of the compounds. Remarkably, two weeks of blue-light supplement increased all compounds: pulegone (362% increase compared to the control), menthofuran (285%), menthone (223%), and menthol (389%). Red light slightly promoted pulegone (256%), menthofuran (178%), and menthol (197%). Interestingly, the accumulation of menthone (229%) or menthofuran (339%) was observed with far-red light treatment. The quantification of glandular trichomes density revealed that no increase under light supplement was confirmed. Blue light treatment even suppressed the glandular trichome formation. No promotion of photosynthesis was observed by pulse-amplitude-modulation (PAM) fluorometry. The present result indicates that light supplements directly promoted the biosynthetic pathways of cyclic monoterpenes.

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Multi-omics analysis of the bioactive constituents biosynthesis of glandular trichome in Perilla frutescens

BMC Plant Biology ◽

10.1186/s12870-021-03069-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Peina Zhou ◽

Mengjiao Yin ◽

Shilin Dai ◽

Ke Bao ◽

Chenglin Song ◽

...

Keyword(s):

Glandular Trichomes ◽

Glandular Trichome ◽

Perilla Frutescens ◽

Morphological Features ◽

Limited Information ◽

Bioactive Constituents ◽

Edible Plant ◽

Cell Factories ◽

Custom Made ◽

Trichome Types

Abstract Background Perilla frutescens (L.) Britt is a medicinal and edible plant widely cultivated in Asia. Terpenoids, flavonoids and phenolic acids are the primary source of medicinal ingredients. Glandular trichomes with multicellular structures are known as biochemical cell factories which synthesized specialized metabolites. However, there is currently limited information regarding the site and mechanism of biosynthesis of these constituents in P. frutescens. Herein, we studied morphological features of glandular trichomes, metabolic profiling and transcriptomes through different tissues. Results Observation of light microscopy and scanning electron microscopy indicated the presence of three distinct glandular trichome types based on their morphological features: peltate, capitate, and digitiform glandular trichomes. The oil of peltate glandular trichomes, collected by custom-made micropipettes and analyzed by LC–MS and GC–MS, contained perillaketone, isoegomaketone, and egomaketone as the major constituents which are consistent with the components of leaves. Metabolomics and transcriptomics were applied to explore the bioactive constituent biosynthesis in the leaves, stem, and root of P. frutescens. Transcriptome sequencing profiles revealed differential regulation of genes related to terpenoids, flavonoids, and phenylpropanoid biosynthesis, respectively with most genes expressed highly in leaves. The genes affecting the development of trichomes were preliminarily predicted and discussed. Conclusions The current study established the morphological and chemical characteristics of glandular trichome types of P. frutescens implying the bioactive constituents were mainly synthesized in peltate glandular trichomes. The genes related to bioactive constituents biosynthesis were explored via transcriptomes, which provided the basis for unraveling the biosynthesis of bioactive constituents in this popular medicinal plant.

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Inheritance of Biochemical and Morphological Characters Associated with Two-spotted Spider Mite Resistance in Pelargonium ×hortorum

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.122.3.373 ◽

1997 ◽

Vol 122 (3) ◽

pp. 373-379 ◽

Cited By ~ 7

Author(s):

Richard Grazzini ◽

Donald Walters ◽

Jody Harmon ◽

David J. Hesk ◽

Diana Cox-Foster ◽

...

Keyword(s):

Spider Mite ◽

Genetic Model ◽

Glandular Trichomes ◽

Glandular Trichome ◽

Morphological Characters ◽

Spider Mites ◽

Trichome Density ◽

Anacardic Acids ◽

High Concentrations ◽

Two Spotted Spider Mite

Diploid zonal geraniums (Pelargonium ×hortorum) are able to resist attack by small arthropod pests such as the two-spotted spider mite (Tetranychus urticae Koch) when exudate produced by tall glandular trichomes contains a high percentage of ω5-unsaturated anacardic acids. Trichomes of susceptible plants exude primarily saturated anacardic acids. Inbred mite-resistant and -susceptible geraniums were reciprocally crossed and the F1, F2, and backcross generations were examined for anacardic acid composition and trichome density. Selected F2 plants were bioassayed for resistance to two-spotted spider mites. High concentrations of ω5-unsaturated anacardic acids in resistant plants are conditioned by a single dominant allele. We propose that inheritance of tall glandular trichome density can be controlled by a small number of loci (possibly as few as one) exhibiting codominance. F2, with low densities of tall glandular trichomes and producing ω5-unsaturated anacardic acids, displayed effective resistance to two-spotted spider mites as measured by mite mortality and fecundity. A genetic model for the biosynthesis of anacardic acids is proposed.

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Spectral properties, gas exchange, and water potential of leaves of glandular and non-glandular trichome types in Datura wrightii (Solanaceae)

Functional Plant Biology ◽

10.1071/fp03178 ◽

2004 ◽

Vol 31 (3) ◽

pp. 267 ◽

Cited By ~ 8

Author(s):

James L. Smith II ◽

J. Daniel Hare

Keyword(s):

Gas Exchange ◽

Spectral Properties ◽

Glandular Trichomes ◽

Chemical Defence ◽

Geographic Location ◽

Glandular Trichome ◽

Datura Wrightii ◽

Significant Difference ◽

Sticky Plants ◽

Trichome Types

Plant trichomes commonly serve a role in mechanical and chemical defence against herbivores, but may also have the potential to alter physiology by reducing the amount of light absorbed by leaves, lowering temperatures, and reducing water loss. Populations of Datura wrightii Regel in southern California produce 'sticky' plants with glandular trichomes and 'velvety' plants bearing non-glandular trichomes. Because stickiness is inherited as a dominant Mendelian trait, and the proportions of sticky plants vary among populations with the moisture availability of their environment, there may be some ecophysiological differences between trichome types that contribute to their ability to survive in a particular geographic location. To examine the possible physiological significance of trichome variation, we measured the spectral properties, midday gas-exchange rates, and water potentials of D. wrightii leaves from sticky and velvety plants growing in a field experiment. The differences in leaf reflectance (0.9%) and absorptance (1.3%) of photosynthetically active radiation (PAR) between trichome types are too small to have any direct physiologically significant effect. Simulations of leaf temperatures based on the difference in leaf absorptances reveal that leaf temperature would be no more than 1°C lower in velvety compared to sticky plants. Gas-exchange measurements revealed no significant difference between types in their transpiration rates or stomatal conductances. In this case, trichome variation may be more important to plant defenses than to physiology.

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Micromorphology and ultrastructure of trichomes of Libyan Salvia fruticosa Mill.

Archives of Biological Sciences ◽

10.2298/abs1301239s ◽

2013 ◽

Vol 65 (1) ◽

pp. 239-246 ◽

Cited By ~ 2

Author(s):

Sheef Al ◽

Sonja Duletic-Lausevic ◽

Dusica Janosevic ◽

Snezana Budimir ◽

Marija Marin ◽

...

Keyword(s):

Glandular Trichomes ◽

Light And Electron Microscopy ◽

Stalk Cell ◽

Secretory Cells ◽

Salvia Fruticosa ◽

Short Stalk ◽

Capitate Trichomes ◽

Leaf Surfaces ◽

Large Round ◽

Peltate Trichomes

Micromorphological and ultrastructural analyses of the leaf trichomes of Salvia fruticosa Mill. were performed by light and electron microscopy. The leaves bear numerous non-glandular unbranched trichomes, and peltate, capitate and digitiform glandular trichomes. Very elongated flagelliform non-glandular trichomes densely covered the leaf surfaces, with especially abundance on the leaf margins. Peltate trichomes consist of a basal epidermal cell, a very short stalk cell and a large round head of eight secretory cells arranged in a circle. Capitate trichomes can be divided into two main types, short-stalked and long-stalked, and further into five subtypes according to the number of stalk cells, morphology and number of glandular head cells. Digitiform trichomes consist of one basal cell, one or two stalk cells and one apical secretory cell, which are of similar diameter and approximately equal length.

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Genome-wide characterization of NtHD-ZIP IV: different roles in abiotic stress response and glandular Trichome induction

BMC Plant Biology ◽

10.1186/s12870-019-2023-4 ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Hongying Zhang ◽

Xudong Ma ◽

Wenjiao Li ◽

Dexin Niu ◽

Zhaojun Wang ◽

...

Keyword(s):

Abiotic Stress ◽

Stress Response ◽

Stress Responses ◽

Leucine Zipper ◽

Regulatory Gene ◽

Glandular Trichomes ◽

Glandular Trichome ◽

Tissue Expression ◽

Abiotic Stress Response ◽

Epidermal Development

Abstract Background The plant-specific homeodomain-leucine zipper class IV (HD-ZIP IV) gene family has been involved in the regulation of epidermal development. Results Fifteen genes coding for HD-ZIP IV proteins were identified (NtHD-ZIP-IV-1 to NtHD-ZIP-IV-15) based on the genome of N. tabacum. Four major domains (HD, ZIP, SAD and START) were present in these proteins. Tissue expression pattern analysis indicated that NtHD-ZIP-IV-1, − 2, − 3, − 10, and − 12 may be associated with trichome development; NtHD-ZIP-IV-8 was expressed only in cotyledons; NtHD-ZIP-IV-9 only in the leaf and stem epidermis; NtHD-ZIP-IV-11 only in leaves; and NtHD-ZIP-IV-15 only in the root and stem epidermis. We found that jasmonates may induce the generation of glandular trichomes, and that NtHD-ZIP-IV-1, − 2, − 5, and − 7 were response to MeJA treatment. Dynamic expression under abiotic stress and after application of phytohormones indicated that most NtHD-ZIP IV genes were induced by heat, cold, salt and drought. Furthermore, most of these genes were induced by gibberellic acid, 6-benzylaminopurine, and salicylic acid, but were inhibited by abscisic acid. NtHD-ZIP IV genes were sensitive to heat, but insensitive to osmotic stress. Conclusion NtHD-ZIP IV genes are implicated in a complex regulatory gene network controlling epidermal development and abiotic stress responses. The present study provides evidence to elucidate the gene functions of NtHD-ZIP IVs during epidermal development and stress response.

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