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Tremendous plant metabolic diversity arises from phylogenetically restricted specialized metabolic pathways. Specialized metabolites are synthesized in dedicated cells or tissues, with pathway genes sometimes colocalizing in biosynthetic gene clusters (BGCs). However, the mechanisms by which spatial expression patterns arise and the role of BGCs in pathway evolution remain underappreciated. In this study, we investigated the mechanisms driving acylsugar evolution in the Solanaceae. Previously thought to be restricted to glandular trichomes, acylsugars were recently found in cultivated tomato roots. We demonstrated that acylsugars in cultivated tomato roots and trichomes have different sugar cores, identified root-enriched paralogs of trichome acylsugar pathway genes, and characterized a key paralog required for root acylsugar biosynthesis, SlASAT1-LIKE (SlASAT1-L), which is nested within a previously reported trichome acylsugar BGC. Last, we provided evidence that ASAT1-L arose through duplication of its paralog, ASAT1, and was trichome-expressed before acquiring root-specific expression in the Solanum genus. Our results illuminate the genomic context and molecular mechanisms underpinning metabolic diversity in plants.

Summary: Characterizing physiological and anatomical changes that underlie rapid evolution following climatic perturbation can broaden our understanding of how climate change is affecting biodiversity. It can also provide evidence of cryptic adaptation despite stasis at higher levels of biological organization.Here, we compared evolutionary changes in populations of Mimulus cardinalis from historically different climates in the north and south of the species' range following an exceptional drought. We grew seeds produced from predrought ancestral plants alongside peak‐drought descendants in a common glasshouse and exposed them to wet and dry conditions.Before the drought, northern ancestral populations expressed traits contributing to drought escape, while southern ancestral populations expressed drought avoidance. Following the drought, both regions evolved to reduce water loss and maintain photosynthesis in dry treatments (drought avoidance), but via different anatomical alterations in stomata, trichomes, and palisade mesophyll. Additionally, southern populations lost the ability to take advantage of wet conditions.These results reveal rapid evolution towards drought avoidance at an anatomical level following an exceptional drought, but suggest that differences in the mechanisms between regions incur different trade‐offs. This sheds light on the importance of characterizing underlying mechanisms for downstream life‐history and macromorphological traits. [ABSTRACT FROM AUTHOR]

Summary 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. [ABSTRACT FROM AUTHOR]

Trichomes, which are special structures on the surfaces of plants, play an important role in plant defense. Trichomes in tomatoes are composed of multiple cells that are divided into glandular and non-glandular trichomes. Glandular trichomes can secrete a diverse array of specialized metabolites and terpenes are the main types. Previous studies have shown that JA and TOR signaling are associated with trichomes, and there may be an interaction between these, but the mechanism remains unclear. In this study, JA signaling and its key transcription factor SlMYC1 were shown to regulate the transcript levels of terpene synthesis precursor-related genes (MEP/MVA pathways). SlTOR positively regulated the formation of type VI trichomes through GC-MS, qRT-PCR, and transient transgenic assays, and the synthesis and accumulation of monoterpenes and sesquiterpenes were positively regulated through the expression of key genes for terpene synthesis. Subsequently, SlTOR was the direct target of SlMYC1 by yeast one-hybrid, GUS, and transient expression assays. Collectively, this study revealed that tomato trichomes were regulated by SlTOR, and SlMYC1 mediated the growth and development of trichomes and the synthesis of terpenes by directly binding the promoter of SlTOR to activate its expression. This lays the foundation for the molecular regulatory mechanism of multicellular trichomes. [ABSTRACT FROM AUTHOR]

This research on Lamiales epidermal anatomy not only provides in‐depth understanding of their structural traits but also highlights the significance of uncovering the inherent antimicrobial resilience embedded within these plants. Such insights hold promise for advancing natural product‐based approaches in medicine, potentially contributing to the development of novel antimicrobial agents inspired by Lamiales unique biological defense mechanisms. Scanning microscopic tools were utilized to conduct foliar epidermal anatomy of nine species that belong to seven genera and four families within the Lamiales order, Plantaginaceae, Scrophulariaceae, Verbenaceae, and Lamiaceae. This approach aimed to gather both qualitative and quantitative data, facilitating the assessment of taxonomic microanatomical significance. The shape of epidermal cells and their anticlinal walls; number of epidermal cells, stomata, and trichomes; type of stomata and trichomes; length and width of epidermal cells, trichomes, stomatal pore, guard cells, and subsidiary cells; and stomatal index were determined statistically. Most of the species examined were amphistomatous and showed extensive array of trichomes diversity. The exploration of Lamiales epidermal micromorphology and their antimicrobial potential were significant for their implications in multidisciplinary fields. The pharmacological research to utilize sustainable agricultural practices prompts avenues to strengths of Lamiales order for the development of novel antimicrobial solutions and ecological benefits. Research Highlights: Diverse trichome morphometry reveals a wide array of trichome structures across Lamiales species.Epidermal microscopic architecture variability of epidermal cell shapes and sizes signifies the interspecies variability.Secondary metabolite localization within microanatomical structures elucidates potential hotspots for antimicrobial compound production. [ABSTRACT FROM AUTHOR]

Trapping trichomes, a common trait found in protogynous trap flowers, are thought to enable interaction with pollinators, promoting both pollen removal and fruit set. However, this hypothesis has yet to be empirically confirmed. In this study, we experimentally tested whether trapping trichomes favour male and female functions in trap flowers. Using protogynous South American Aristolochia esperanzae trap flowers, we observed the temporal variation in both sexual functions and associated them with the wilting of the flower and trapping trichomes. Next, we described the trapping trichomes features associated with the capture, entrapment and release of pollinators. Finally, we used manipulative experiments involving trapping trichome removal to quantify their influence on pollinator entrapment, pollen removal and fruit set. While flowers wilted after the end of the female phase, the trapping trichomes only wilted some hours after pollen presentation, promoting a delay in the exit of pollinators, so they carried pollen. Trapping trichomes features, such as a density gradient towards the interior of the tube, unidirectional orientation and epicuticular waxes, may be important in the capture and entrapment of pollinators. Trapping trichome removal decreased drastically the probability of pollinator entrapment and pollen removal, leading to no fruit set. These results indicate that the evolution and maintenance of trapping trichomes in trap flowers probably occurred through selective pressures from both sexual functions and highlight their role in the functioning of this highly phenotypically specialized pollination system. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

This study investigates the micromorphology and morphometrics of aggregate fruit (ripe hypanthium and achene) of eight wild Rosa species collected throughout Serbia. Field research was conducted to find roses at different habitats, collecting 1,836 aggregate fruits with 25,999 achenes from 137 shrubs. Multicellular glandular trichomes are found on the hypanthium surface, while long and short stalk capitate glandular trichomes were observed on the fruits of R. gallica, R. pendulina, R. tomentosa and R. villosa. Numerous unicellular non-glandular trichomes were found inside the urceolate hypanthium and on the surface of most studied achenes, except for R. spinosissima species. Micromorphological analysis revealed three types of exocarp ornamentation: scalariform (R. dumetorum, R. tomentosa and R. micrantha), reticulate (R. gallica, R. arvensis, R. spinosissima and R. villosa) and reticulate-smooth (R. pendulina). Morphometric analysis indicated significant differences among the 14 morphological characters. Achene length was the most significant morphometric feature for identifying Rosa species (P˂0.05). The results contribute to our poor knowledge of rose fruit morphology and provide some well-defined microcharacters that could be used as additional features for species delimitation. [ABSTRACT FROM AUTHOR]

Hairs or trichomes distributed on the base of filaments in the morning glory family, known as staminal trichomes, differ from those found on other plant parts and have been recognized for their taxonomic value for over a century. In this study, our aim was to investigate the appearance of staminal trichomes in the tribe Ipomoeeae Hall. f., a significant tribe within the family Convolvulaceae, and assess their taxonomic implications. Micromorphological examinations were conducted using clearing techniques on 73 taxa from seven out of eight genera within the tribe, and the data were analyzed using factor analysis of mixed data (FAMD). The results show that, among all examined taxa, only two species lacked staminal trichomes. Glandular staminal trichomes were the most common type observed, and they were the only type observed in Ipomoea, Paralepistemon, Rivea, Stictocardia, and most Argyreia species. Nonglandular staminal trichomes were restricted to Astripomoea, Lepistemon, and some Argyreia taxa. The glandular trichomes in Ipomoea exhibited the largest variation and overlapped with other glandular trichome-bearing genera. However, genera with nonglandular trichomes were readily distinguishable from each other. Both glandular and nonglandular trichomes were basically composed of a stalk and apical cell, yet they varied in shape, size, density, and distribution pattern. This study provides a detailed examination and application of microscale features, emphasizing the significance of micromorphology in plant taxonomy. [ABSTRACT FROM AUTHOR]

Herbivorous insects assess and choose their potential host plants based on traits that may correlate with host suitability or quality. These traits may operate as cues for better resources, noxious chemicals, or fewer competitors and enemies. Interactions between insects and their host plants may also be modulated by the nutritional value of the plant, by plant chemical stimuli, or by physical traits such as trichomes. Differences in chemical or physical cues among plants may convey information about diet suitability. Several studies have addressed the topic of differences in plant traits between host and non-host plants; fewer have addressed these differences among potential host plants. We have studied the effect of chemical and physical plant traits on the feeding and oviposition preferences of the oligophagous herbivore Epilachna paenulata (Coleoptera: Coccinellidae) and two of its host plants, Cucurbita maxima and Cucurbita moschata (Cucurbitaceae). We first typified the volatile and non-volatile chemical profiles and the trichome distribution of the plants. Then, using behavioral assays, we evaluated feeding and oviposition preferences of E. paenulata. Further, to assess a correlation between oviposition preferences and offspring survival, we measured larval performance as indicated by survival, mass, and time to complete each instar. Female longevity in both Cucurbita host plants was also evaluated. Our results show that the congeneric plants bear differences in their chemical profiles, including volatile organic compounds, leaf waxes, and leaf parenchyma metabolites. Trichome abundance was also different, with C. maxima presenting fewer hairs. Epilachna paenulata females laid significantly more eggs in C. maxima, regardless of the plant they were raised as larvae. Female longevity on C. maxima was higher, but larval performance showed no difference between both plants. The proximate causes mediating female oviposition preferences may then involve trichome abundance, oviposition deterrents, toxic substances, or a combination of these factors. [ABSTRACT FROM AUTHOR]

A new subalpine species of Bufonia sect. Longipedicellata from the Zagros Mountains in west Iran is described and illustrated here. It colonizes mountain slopes with gravelly, stony, and scree substrates in one locality of Chaharmahal and Bakhtiari province, preferably with a western and north‐west orientation, at elevations between 2700 and 3100 m a.s.l. The new species, B. darvishii, is diagnosed against the morphologically similar B. macrocarpa. The two species share similarities such as filiform and long pedicels, a lax panicle‐cyme inflorescence, distribution pattern of trichomes, and long peduncles. However, the new species stands out with semi‐shrub life form, its greater height, retention of the previous year's stems, cymes bearing more flowers, orbicular petals, larger petals, a broadly ovate ovary, larger sepals with more pronounced nervation, shorter pedicels, larger flowers, etc. Bufonia darvishii is proposed to be Critically Endangered (CR) following the guidelines of the IUCN. [ABSTRACT FROM AUTHOR]

Background: This study was aimed to determine the taxonomic position and delimitation of fifteen Lamiaceae taxa using leaf epidermal morpho-anatomical features in Lahore. A main objective of the study was also the revision and upgradation of Lamiaceae taxa in the flora of Pakistan, as no details of studied species are found in the flora of Pakistan. Methods: The examination of significant anatomical parameters, such as epidermal cell shape and size, stomatal types, guard and subsidiary cells shape and size, stomatal cavity size, trichome size and shape, oil droplets, crystals, and secretory cavity characteristics were studied using light microscopic (LM) and scanning electron microscopic (SEM) techniques. Among all the studied Lamiaceae species, these anatomical features varied significantly. Principal component analysis and correlation were done to distinguish the species' similarities. Results: Most species had pentagonal and hexagonal epidermal cells with straight anticlinal wall thickness. On the adaxial surface, paracytic stomata were found in Ocimum basilicum L. and Rosmarinus officinalis L. Diacytic stomata was observed in Ajuga reptans L. and anisocytic stomata in Galeopsis tetrahit L. In the abaxial surface, trichomes were present in five species, i.e., Mentha suaveolens Ehrh. A. reptans, Thymus vulgaris L., M. haplocalyx, and Salvia splendens Ewat. In S. splendens, peltate and glandular trichomes were seen whereas, in other species, trichomes were long, unbranched glandular and had tapering ends. In adaxial side trichomes were present only in M. suaveolens, A. reptans, S. bazyntina, O. basciculum, S. splendens, S. officinalis, S. rosemarinus. In other species, trichomes were absent on the adaxial surface. In abaxial view, M. suaveolens had the largest length of trichomes, and O. basciculum had the smallest. S. splendens L. had the largest trichome width, while T. vulgaris had the smallest. Conclusion: Hence, according to these findings, morpho-anatomical traits are useful for identifying Lamiaceae taxa. Also, there is a need of upgradation and addition of studied taxa in flora of Pakistan comprehensively. [ABSTRACT FROM AUTHOR]

To reduce negative effects of floral visitation by ants, which do not serve as reliable cross-pollinators, some plants have developed a non-floral, stem-based defense mechanism called greasy pole syndrome. In the present study, we examined the effects of two surface features (trichomes and three-dimensional epicuticular wax coverage) on stems of Alliaria petiolata plants on visiting frequencies, travelled distances, and running velocities of Lasius niger ants. The experiments were performed with stem samples prepared from different (apical and basal) stem portions showing different surface morphologies (smooth control, covered by wax and trichomes + wax, respectively). The control, mechanically wiped stem samples lacking any surface features were significantly more often visited by ants, where they travelled significantly longer distances and moved with significantly higher velocities, compared to the intact stems. The apical and basal stem portions showed no significant differences in the measured parameters. Based on data obtained, we conclude about the main contribution of the wax to the greasy pole function of the A. petiolata stem via reduction of ant adhesion to the wax-bearing stem surface, whereas trichomes presumably serve as the first barrier for ants approaching usually from the ground level and protect the fragile wax coverage from an excessive deterioration. [ABSTRACT FROM AUTHOR]

Factors that mediate insect herbivore sabotaging behaviour of host plant latex defences remain under debate. The most prominent hypothesis suggests that the anatomy of the host plant's laticifers determines trenching or vein‐cutting behaviour, but there are inconsistencies in the literature. In addition to latex, other plant defences have been shown to affect plant natural enemies, but experimental studies comparing the effects of multiple defences on herbivore performance and behaviour are scarce. In this study, we investigated the anatomy of the laticifers of Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), an exotic milkweed of southeastern Brazil, as well as the sabotaging behaviour of larvae of southern monarch, Danaus erippus (Cramer), and queen butterfly, Danaus gilippus (Cramer) (Lepidoptera: Nymphalidae) on this host plant. We also reviewed the sabotaging behaviour of larvae reared on the native milkweed Asclepias curassavica L. (Apocynaceae) from previous studies, as well as the description of the anatomy of its laticifers. As we found no correspondence between sabotaging behaviour of southern monarchs and queens and the anatomy of the host plants' laticifers, we tested whether structural defences of C. procera leaves (latex, waxes and trichomes) affected sabotaging behaviour and larval performance of southern monarch larvae. The structural barriers of this well‐defended host affected larvae in different ways: Southern monarchs developed more slowly on control leaves than on leaves from which wax had been removed, and only latex removal reduced the frequency of sabotaging behaviour. Regardless of the defence removal treatment, frequencies of trenching behaviour decreased and vein‐cutting behaviour increased as larvae developed. Overall, our results show that several factors in addition to the anatomy of laticifers affect sabotaging behaviour of southern monarchs and queens, including larval ontogeny, danaine species and latex outflow. This evidence suggests a behavioural plasticity in the sabotaging behaviour of larvae of both southern monarchs and queens. [ABSTRACT FROM AUTHOR]

SUMMARY 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. [ABSTRACT FROM AUTHOR]

To investigate the morphological factors contributing to resistance to yellow mite, Polyphagotarsonemus latus and thrips, Scirtothrips dorsalis in chilli, an analysis was conducted on 15 chilli genotypes, examining various traitsviz. trichome density, length, and angle, along with leaf thickness, length, breadth, and area. Among the genotypes, SL-696 exhibited the highest trichome density (87.67/0.75mm2), while IS-267 displayed the lowest density (19/0.75mm2), and C-142 lacked trichomes altogether. In terms of trichome length, SR-4611 had the maximum (5.02 µm), contrasting with PUP-661, which had the minimum length (1.16 µm). PCH-757 featured the highest trichome angle (44.47°), while AC-105° showed the lowest angle. C-142 demonstrated the greatest leaf thickness (264.67 µm), whereas SL-466 exhibited the smallest thickness (79.60 µm). PUP-661 displayed the highest values for leaf length (9.10 cm), breadth (3.93 cm), and area (148.19 cm2), with PP-418 exhibiting the minimum values for length (3.87 cm), breadth (1.40 cm), and leaf area (44.03 cm2). Analyses of correlations between damage score/LCI and various morphological leaf traits indicated weak, negative, yet nonsignificant associations with trichome density, length, angle, and leaf thickness. Conversely, leaf area demonstrated a weak positive but nonsignificant correlation with the damage score. [ABSTRACT FROM AUTHOR]

Odontarrhena muralis (Brassicaceae) is a nickel hyperaccumulator species from the Balkans used as a "metal crop" in nickel phytomining. This study aimed to determine the elemental distribution, focusing on nickel, in fresh‐hydrated plant tissue (stems, leaves and inflorescences), to clarify where nickel is localized at the tissue and cellular scale‐level and to infer the physiological response to its hypertolerance and hyperaccumulation. For the analysis, intact plant organs of O. muralis were subjected to elemental imaging using synchrotron‐based micro‐X‐ray fluorescence (μXRF). The predominant distribution of nickel occurs in the epidermal tissue and at the base of the trichomes, which are also the main sinks for calcium deposition. The obtained results represent a further contribution to the knowledge of the physiological characteristics of this hyperaccumulating "metal crop" species and, consequently, to its application in sustainable metal extraction using phytomining. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of Botanical Research is the property of Bulletin of Botanical Research Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Relevance. Oenothera tetragona is an ornamental plant used in folk medicine. Until now, studies of the biological characteristics of the Oenothera tetragona have not been carried out on the territory of the NonChernozem zone of the Russian Federation.The purpose of the work is the introduction and biological study of the Oenothera tetragona in the NonChernozem zone of Russia in the conditions of the Moscow region.Methodology. The experiment was based on two-month-old seedlings according to a 60x30 cm pattern. Phenological observations and biometric measurements (during the mass flowering phase) were carried out according to the methods adopted at VILAR (All-Russian scientific research Institute of medicinal and aromatic plants). Experimental data were processed according to B.A. Dospehov. Weather conditions were checked on the Weather and Climate website. Microspecimens were prepared according to methods for light microscopy.Results. In the conditions of the Moscow region the period from the beginning of the growing season to mass fruiting in Oenothera tetragona Roth. averages about 110-115 days. The plant is well adapted: it goes through the entire seasonal cycle of growth and development. The population includes Oenothera tetragona Roth. includes many variable biotypes, which indicates the possibility of targeted selection of forms with useful traits. The main assessment of breeding material can be carried out, starting from the second year of plant life, based on a set of interrelated quantitative traits (height, number of generative shoots, etc.). Some anatomical features of the epidermis of the Oenothera tetragona leaf have been studied for the first time; the number of covering trichomes and the number of stomata per 1 mm2 were determined. As a result of microscopic examination of the epidermis of leaf plates of O. tetragona Roth.: the presence of three groups was revealed, which differed in microscopic characteristics (shape and number of stomata, pubescence) in the absence of a noticeable correlation with the main phenotypic characteristics.

Abstract Background Grapevine (Vitis) is one of the world’s most valuable fruit crops, but insect herbivory can decrease yields. Understanding insect herbivory resistance is critical to mitigating these losses. Vitis labrusca, a wild North American grapevine species, has been leveraged in breeding programs to generate hybrid grapevines with enhanced abiotic and biotic stress resistance, rendering it a valuable genetic resource for sustainable viticulture. This study assessed the resistance of V. labrusca acc. ‘GREM4’ and Vitis vinifera cv. ‘PN40024’ grapevines to Popillia japonica (Japanese beetle) herbivory and identified morphological and genetic adaptations underlying this putative resistance. Results ‘GREM4’ displayed greater resistance to beetle herbivory compared to ‘PN40024’ in both choice and no-choice herbivory assays spanning periods of 30 min to 19 h. ‘GREM4’ had significantly higher average leaf trichome densities than ‘PN40024’ and beetles preferred to feed on the side of leaves with fewer trichomes. When leaves from each species that specifically did not differ in trichome densities were fed on by beetles, significantly less leaf area was damaged in ‘GREM4’ (3.29mm2) compared to ‘PN40024’ (9.80mm2), suggesting additional factors beyond trichomes contributed to insect herbivory resistance in ‘GREM4’. Comparative transcriptomic analyses revealed ‘GREM4’ exhibited greater constitutive (0 h) expression of defense response and secondary metabolite biosynthesis genes compared to ‘PN40024’, indicative of heightened constitutive defenses. Upon herbivory, ‘GREM4’ displayed a greater number of differentially expressed genes (690) compared to ‘PN40024’ (502), suggesting a broader response. Genes up-regulated in ‘GREM4’ were enriched in terpene biosynthesis, flavonoid biosynthesis, phytohormone signaling, and disease defense-related functions, likely contributing to heighted insect herbivory defense, while genes differentially expressed in ‘PN40024’ under herbivory were enriched in xyloglucan, cell wall formation, and calcium ion binding. The majority of genes implicated in insect herbivory defense were orthologs with specific expression patterns in ‘GREM4’ and ‘PN40024’, but some paralogous and genome-specific genes also likely contributed to conferring resistance. Conclusions Our findings suggest that ‘GREM4’ insect herbivory resistance was attributed to a combination of factors, including trichomes and unique constitutive and inducible expression of genes implicated in terpene, flavonoid, and phenylpropanoid biosynthesis, as well as pathogen defense.

Extended Abstract Background: The genus Acer L. (maples) from the Aceraceae are mostly deciduous trees, almost all of which are distributed in the temperate regions of the Northern Hemisphere. This genus contains 148-150 species around the world, and the presence of 8-10 native species of this genus has been mentioned in different floras of Iran. Some species of maples in Hyrcanian forests have great commercial value, and the height of these trees reaches 40-45 m. Maples are the major vegetation elements in most forest ecosystems of Iran. Hyrcanian forests in the north of Iran contain the highest diversity of this genus. Despite the molecular and morphological studies on the taxa of the genus in the world, no comprehensive studies have been conducted on its micro-morphological characteristics. Therefore, the present research describes the taxonomic value of the anatomical features of the leaf epidermis and pollen morphology of the members of this genus in Iran. Methods: Eleven maple taxa available in Iran (nine native and two introduced taxa), mainly from Hyrcanian and Zagros ecosystems, were collected and analyzed in the current study. The investigated taxa were A. hyrcanum, A. velutinum, A. platanoides, A. mazandaranicum, A. campesstre, A. cappadocicum, A. negundo, A. palmatum, A. monspessulanum subsp. cinerascens, A. monspessulanum subsp. turcomanicum, and A. monspessulanum subsp. ibericum. The leaf samples of each individual were prepared from the branches grown in the sun and dried with the herbarium sample method to prevent mold. Dried leaf samples were placed in boiling water for 3 min to prepare dissections. Then, thin slices were prepared from the dorsal and ventral epidermis from the middle of the leaf and in the vicinity of the midrib using a surgical blade. To remove the color of chlorophyll and make the samples transparent, they were placed in a sodium hypochlorite solution for 5 min. After washing with distilled water, they were photographed and studied under a light microscope. For electron microscopy, the dorsal and ventral epidermises and the pollen samples of the taxa were stabled on aluminum stubs. Then, a very thin gold layer was sprinkled on the surface of all pollen and leaf samples using a gold sputter coater and then photographed using a Philips Scanning Electron Microscope. The voltage intensity was 20 kV, and the image magnification was set to 2500-5100 x. Epicuticular waxes, trichomes, epidermal cell wall shape, stomatal type, pollen type, pollen morphological characteristics, and the stomatal density and index were classified and studied from the prepared microphotographs. Results: The morphology of epicuticular wax was absolutely unique in such taxa as A. velotinum, A. mazandaranicum, A. hyrcanum, A. platanoides, and even some subspecies of A. monspessulanum. The most structured type of epicuticular waxes was observed in A. velotinum, showing circular rosette-like structures formed around some stomata, which could not be seen in the other taxa. The dorsal leaf surface in A. platanoides was also uniquely covered with a completely smooth and uniform layer of wax. Certain wax structures were observed on the surfaces of A. monspessulanum subsp. cinerasens and A. mazandaranicum, making the surface of the epidermal cells appear prominent in the former and indented in the latter taxa. The highest stomatal index and the number of stomata per unit area belonged to two non-native species, namely A. palmatum and A. negundo, and these parameters were lowermost in A. mazandaranicum, A. monspessulanum subsp. turcomanicum, A. velutinum var. velutinum, and A. monspessulanum subsp. cinerascens. Many of the stomata are covered and buried under the thick layers of the epicuticular wax, and there are trichomes and wax crystalloids around other stomata to reduce the rate of evaporation and transpiration. Therefore, it can be acknowledged that the mentioned native taxa have higher drought resistance than others. The epidermal cell wall pattern of the taxa was classified into three different types, the most distinctive of which was seen in A. platanoides, having a completely wavy and puzzle-like wall. Relatively wavy wall was seen only in the epidermis cells of A. negundo. The other taxa showed smooth and straight cell walls. The arrange of subsidiary cells of the stomata was anomocytic in all taxa while the paracytic type was completely distinctive and dominant in A. mazandaranicum. Trichomes in all the owning taxa were simple and branchless, divided into two short- and long-size groups. None of the morphological characteristics of the pollen, such as pollen shape (isopolar prolate to spheroidal), exine ornamentation (striate), the form of pollen colpi, and even the number of pollen pores (Tricolporate), revealed a specific differentiation exclusive to a certain taxon. Conclusion: The results of the current research reveal that the micro-morphological traits of leaves can help remove the taxonomical obstacles of the genus Acer while the pollen type and morphology do not provide such a capability for the genus. In general, the differentiation of epidermal characteristics among the studied maple taxa shows that the leaf dorsal has useful micromorphological characteristics, especially in terms of epicuticular waxes, which can play an important role in classifying, describing, and determining the boundaries of the taxa to be used as a useful tool in plant biosystematics.

Abstract 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.

Background: Grapevine (Vitis) is one of the world's most valuable fruit crops, but insect herbivory can decrease yields. Understanding insect herbivory resistance is critical to mitigating these losses. Vitis labrusca, a wild North American grapevine species, has been leveraged in breeding programs to generate hybrid grapevines with enhanced abiotic and biotic stress resistance, rendering it a valuable genetic resource for sustainable viticulture. This study assessed the resistance of V. labrusca acc. 'GREM4' and Vitis vinifera cv. 'PN40024' grapevines to Popillia japonica (Japanese beetle) herbivory and identified morphological and genetic adaptations underlying this putative resistance. Results: 'GREM4' displayed greater resistance to beetle herbivory compared to 'PN40024' in both choice and no-choice herbivory assays spanning periods of 30 min to 19 h. 'GREM4' had significantly higher average leaf trichome densities than 'PN40024' and beetles preferred to feed on the side of leaves with fewer trichomes. When leaves from each species that specifically did not differ in trichome densities were fed on by beetles, significantly less leaf area was damaged in 'GREM4' (3.29mm2) compared to 'PN40024' (9.80mm2), suggesting additional factors beyond trichomes contributed to insect herbivory resistance in 'GREM4'. Comparative transcriptomic analyses revealed 'GREM4' exhibited greater constitutive (0 h) expression of defense response and secondary metabolite biosynthesis genes compared to 'PN40024', indicative of heightened constitutive defenses. Upon herbivory, 'GREM4' displayed a greater number of differentially expressed genes (690) compared to 'PN40024' (502), suggesting a broader response. Genes up-regulated in 'GREM4' were enriched in terpene biosynthesis, flavonoid biosynthesis, phytohormone signaling, and disease defense-related functions, likely contributing to heighted insect herbivory defense, while genes differentially expressed in 'PN40024' under herbivory were enriched in xyloglucan, cell wall formation, and calcium ion binding. The majority of genes implicated in insect herbivory defense were orthologs with specific expression patterns in 'GREM4' and 'PN40024', but some paralogous and genome-specific genes also likely contributed to conferring resistance. Conclusions: Our findings suggest that 'GREM4' insect herbivory resistance was attributed to a combination of factors, including trichomes and unique constitutive and inducible expression of genes implicated in terpene, flavonoid, and phenylpropanoid biosynthesis, as well as pathogen defense. [ABSTRACT FROM AUTHOR]

Labdane-related diterpenoids (LRDs), a subgroup of terpenoids, exhibit structural diversity and significant commercial and pharmacological potential. LRDs share the characteristic decalin–labdanic core structure that derives from the cycloisomerization of geranylgeranyl diphosphate (GGPP). Labdanes derive their name from the oleoresin known as 'Labdanum', 'Ladano', or 'Aladano', used since ancient Greek times. Acetylated labdanes, rarely identified in plants, are associated with enhanced biological activities. Chemical analysis of Cistus creticus subsp. creticus revealed labda-7,13(E)-dien-15-yl acetate and labda-7,13(E)-dien-15-ol as major constituents. In addition, novel labdanes such as cis -abienol, neoabienol, ent -copalol, and one as yet unidentified labdane-type diterpenoid were detected for the first time. These compounds exhibit developmental regulation, with higher accumulation observed in young leaves. Using RNA-sequencing (RNA-seq) analysis of young leaf trichomes, it was possible to identify, clone, and eventually functionally characterize labdane-type diterpenoid synthase (diTPS) genes, encoding proteins responsible for the production of labda-7,13(E)-dien-15-yl diphosphate (endo -7,13-CPP), labda-7,13(E)-dien-15-yl acetate, and labda-13(E)-ene-8 α -ol-15-yl acetate. Moreover, the reconstitution of labda-7,13(E)-dien-15-yl acetate and labda-13(E)-ene-8 α -ol-15-yl acetate production in yeast is presented. Finally, the accumulation of LRDs in different plant tissues showed a correlation with the expression profiles of the corresponding genes. [ABSTRACT FROM AUTHOR]

The morphological diversity of trichomes and pappi in 20 common Asteraceae members were studied from the standpoint of species identification. Thirteen of these species bear trichomes on all surfaces and 16 types of trichomes were recorded. Non-glandular, multicellular, uniseriate trichomes with long terminal cell are the most common type recorded at 87 observed surfaces of 16 species. Some trichome types were restricted to one or two species. The trichomes of Leucomeris spectabilis are being reported for the first time. The pappi were recorded in 13 species and their morphology is quite characteristic of species and genera. Separate dichotomous keys are constructed to help identify the species on the basis of trichomes and pappi exclusively. [ABSTRACT FROM AUTHOR]

We describe and illustrate Freziera antioquensis (Pentaphylacaceae), a new species, known from two specimens collected in the Cordillera Occidental of Colombia, Antioquia department, in the Chocó Biogeographic region. Among the morphological attributes that distinguish this new species from its congeners is the dense pubescence, with long trichomes, covering the young branches, petioles and underside of the leaf blades, as well as the absence of trichomes on the bracteoles and sepals. With the description of this species, Colombia has about 27 species of Freziera, 12 of which are endemic and known from only one or two herbarium specimens. [ABSTRACT FROM AUTHOR]

We conducted a comparative micromorphological study on the leaves of all nine genera of the Rosaceae tribe Spiraeeae, including the monotypic Korean genus Pentactina. Spiraeeae possess amphistomatic and hypostomatic leaves. Leaf epidermal characteristics varied with the morphology of stomatal complexes, epidermal cells, trichomes, and epicuticular waxes. Specific leaf epidermal features may be systematically relevant for identifying lower taxonomic levels, genera, and/or species. For example, papillate epidermal cell types were consistently observed in Spiraea sect. Calospira. Hirtellous trichomes are diagnostic characteristics of the genera Holodiscus and Kelseya among this tribe. Short-stalked capitate glandular and crispate villous trichomes were only observed in Holodiscus microphyllus and Spiraea douglasii , respectively. We also confirmed that leaf epidermal characteristics strongly support the independent taxonomic position of the Korean endemic Pentactina and the transfer from Physocarpus to Spiraea of Physocarpus insularis. Moreover, we identified xeromorphic features in the studied taxa and inferred their ecological functions, such as water repellence and anti-transpirant activities. This study presents new perspectives for future research on character evolution and xeromorphic adaptation on the basis of leaf epidermal characteristics. [ABSTRACT FROM AUTHOR]

The genus Utricularia (bladderworts) species are carnivorous plants that prey on invertebrates using traps with a high-speed suction mechanism. The outer trap surface is lined by dome-shaped glands responsible for secreting water in active traps. In terminal cells of these glands, the outer wall is differentiated into several layers, and even cell wall ingrowths are covered by new cell wall layers. Due to changes in the cell wall, these glands are excellent models for studying the specialization of cell walls (microdomains). The main aim of this study was to check if different cell wall layers have a different composition. Antibodies against arabinogalactan proteins (AGPs) were used, including JIM8, JIM13, JIM14, MAC207, and JIM4. The localization of the examined compounds was determined using immunohistochemistry techniques and immunogold labeling. Differences in composition were found between the primary cell wall and the cell secondary wall in terminal gland cells. The outermost layer of the cell wall of the terminal cell, which was cuticularized, was devoid of AGPs (JIM8, JIM14). In contrast, the secondary cell wall in terminal cells was rich in AGPs. AGPs localized with the JIM13, JIM8, and JIM14 epitopes occurred in wall ingrowths of pedestal cells. Our research supports the hypothesis of water secretion by the external glands. [ABSTRACT FROM AUTHOR]

Understanding the evolutionary forces that maintain phenotypic variation in ecologically relevant traits has long been one of the central goals of evolutionary ecology. While the maintenance of variation in plant defense is most often hypothesized to be due to trait trade-offs or spatiotemporal variation in herbivore abundance, the role that heterogeneous selective agents may play on the maintenance of variation in plant defense is less examined. Trichomes are hair-like appendages on plant surfaces that can defend against multiple damaging agents such as pathogens, herbivores, and UV radiation. It is currently unknown however if conflicting selection from such heterogeneous agents of damage may act to maintain the variation observed in trichome traits. Here, we assess whether trichomes serve as an herbicide resistance trait and how it coincides with the conventionally studied defensive strategy of herbivory resistance. In a series of experiments, we exposed the annual invasive velvetleaf (Abutilon theophrasti) to glyphosate (active ingredient in "Roundup") to investigate whether trichome traits (type and density) are linked to herbicide resistance and to test whether herbicide influences selection on plant trichomes. We found that an increased proportion of branched trichomes positively impacted herbicide resistance and chewing herbivory resistance. We also found evidence that glyphosate imposes positive selection on branched trichomes in velvetleaf. Overall, our results indicate that branched trichomes can contribute to both herbicide and herbivory resistance, serving a concordant rather than conflicting role to reduce plant injury. Our findings further suggest that novel anthropogenic agents of selection can alter the composition of plant defense traits, potentially impacting trait-mediated interactions among external stressors. [ABSTRACT FROM AUTHOR]

Leaf trichomes are derived from epidermal cells and serve an important function in regulating leaf heat balance and gas exchange. Variation in leaf functional traits is critical for predicting how plants will react to global climate change. In this study, we aimed to investigate how leaf trichome densities vary along large geographic gradients and how they interact with stomata in response to environmental change. We investigated the leaf trichome densities of 44 Quercus variabilis populations in Eastern Asia (24°–51.8° N, 99°–137° E) and their correlation with climatic factors and stomatal traits. In addition, 15 populations were grown in a common garden to study their adaptive variation and coordination with stomata. The mean value of trichome density in situ conditions was 459.78 trichome mm−2 with a range of 325.79–552.38 trichome mm−2. Trichome density increased with latitude and decreased with longitude. Both temperature and precipitation reduced the trichome density. Moreover, trichome density was positively correlated with stomatal density whether in situ or in the common garden, and both increased with drought. Our results suggested that leaf trichomes possess highly adaptive variation and are in close coordination with stomata in response to climate change. Our findings provide new insights toward elucidating the interactions between leaf traits and the adaptive strategies of plants under climate change. [ABSTRACT FROM AUTHOR]

Trichomes are well-known efficient plant defense mechanisms to limit arthropod herbivory, especially in Solanaceae. The present study aims to evaluate the impact of trichome types on the development, survival and dispersal of Tetranychus urticae, and the phytoseiid predatory mite Typhlodromus (Anthoseius) recki. Six Solanum lycopersicum cultivars and two wild Solanum species, S. cheesmaniae and S. peruvianum, presenting contrasting densities and types of trichomes, were considered. Cultivars and species were characterized by counting each trichome type on leaves, petioles and stems. Mites stuck on petiole and stem and alive mites on the leaflet used for mite release and in the whole plant were counted three weeks after T. urticae plant infestation. Tetranychus urticae settlement and dispersal were differently affected by trichomes. Trichome types V and VI did not affect settlement and dispersal, whereas trichome types I and IV on the petiole had the highest impacton mites. Trichomes on leaves slightly affected mite establishment, there appears to be a repellent effect of trichome types I and IV. The low densities of both T. urticae and its predator detected for the cv. Lancaster could not be clearly associated to the trichome types here considered. The predator did not seem to be affected by plant characteristics, but rather by T. urticae numbers on the plant. The trichome traits unfavorable to T. urticae, did not affect the predator which showed high efficiency to control this pest on all the plant genotypes considered, but at a favorable predator:prey ratio (1:1). Altogether, these results are encouraging for the use of T. (A.) recki as a biological control agent of T. urticae regardless of the trichome structure of the tomato cultivars, but other conditions should be tested to conclude on practical implementations. [ABSTRACT FROM AUTHOR]

Some predators prefer to settle on leaf patches with microstructures (e.g., trichomes and domatia), leaving traces on the patches. Herbivorous arthropods, in turn, select leaf patches in response to these traces left by predators. It remains unclear whether traces of predators on leaf patches affect the distribution of herbivorous prey within plants through plant microstructure. Therefore, we examined the distribution of herbivorous mite (Tetranychus urticae) and predatory mite (Phytoseiulus persimilis) by investigating their oviposition pattern. We used a kidney bean plant (Phaseolus vulgaris) with two expanded primary leaves and the first trifoliate leaf, focusing on leaf trichomes as the microstructure. The density of trichomes was higher on the first trifoliate leaf than on the primary leaves and on the abaxial surface of the leaves than on the adaxial surface. Adult female P. persimilis laid more eggs on the first trifoliate leaf to the primary leaves. Although adult female T. urticae preferred to oviposit on the abaxial surface of primary leaves, previous exposure of plants to predators diminished this preference. The altered egg distribution would be a response to the traces of P. persimilis rather than eggs of P. persimilis. Our findings indicate that T. urticae reproduces on leaf patches with traces of predators without altering their oviposition preference. Given that the presence of predator traces is known to reduce the reproduction of T. urticae, it may have a substantial effect on the population of T. urticae in the next generations on kidney bean plants. [ABSTRACT FROM AUTHOR]

The article titled "Sonerila konkanensis Resmi & Nampy (Melastomataceae) - an addition to the flora of Karnataka, India" discusses the discovery of a new plant species in Karnataka, India. The Sonerila konkanensis belongs to the Melastomataceae family and is a caulescent herb. It was identified in the Thirthahalli taluk of the Shivamogga district in Karnataka. The article provides a detailed description of the plant's characteristics and habitat. This finding contributes to the knowledge of the flora in Karnataka and highlights the importance of the Western Ghats region for plant diversity. [Extracted from the article]

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. [ABSTRACT FROM AUTHOR]

The genus Phlomis is one of the largest genera in the Lamiaceae family and includes species used since ancient times in traditional medicine, as flavoring for food and as fragrance in cosmetics. The secretory structures (represented by glandular trichomes) as well as the essential oils produced by them constitute the subject of this review. While representatives of this genus are not typically regarded as large producers of essential oils compared to other species of the Lamiaceae family, the components identified in their essential oils and their biological properties necessitate more investigation of this genus. A comprehensive analysis of the specialized literature was conducted for each of the 93 currently accepted species to identify all the results obtained by researchers regarding the secretory structures and essential oils of this genus up to the present time. Glandular trichomes, still insufficiently studied, present morphological peculiarities that differentiate this genus within the family: they are of two categories: capitate (with a wide distribution in this genus) and dendroid. The peltate trichomes, characteristic of many species of this family, are absent. The essential oils from the species of the genus Phlomis have been much more widely studied than the secretory structures. They show considerable variability depending on the species and the environmental conditions. [ABSTRACT FROM AUTHOR]

Premise of research. While carrying out a taxonomic revision of Kaunia , uncommon types of trichomes and arrangement of trichomes on the leaves of Kaunia gynoxymorpha and Kaunia pachanoi were observed. Moreover, the trichome arrangement is not usual for either Kaunia or most of Eupatorieae. In this study, we aim to describe the leaf blade trichomes and indumentum in these two species and discuss, along with other anatomical characteristics, their ecological role and potential adaptation to dry environments. Methodology. We used traditional light microscopy, scanning electron microscopy, and fluorescence microscopy to examine leaf blade anatomical characteristics. We applied histochemical techniques to the leaves of both studied species to determine the presence of cutinized cell walls, which may influence apoplastic water flow in trichomes. Pivotal results. Our results show two-armed trichomes in K. gynoxymorpha that are unusual in the tribe Eupatorieae. The arrangement of glandular and nonglandular leaf trichomes of the two studied species in tufts of 3–10 trichomes, sunken in surface crypts, is also uncommon. Conclusions. These tufts of trichomes and other anatomical and histochemical evidence suggest that nonglandular trichomes and their arrangement in tufts in K. gynoxymorpha and K. pachanoi provide adaptive advantages by combining physical, mechanical, and biochemical functions to grant protection against drought and high light intensity, among other adverse conditions. [ABSTRACT FROM AUTHOR]

Trichomes are common in plants from dry environments, and despite their recognized role in protection and defense, little is known about their role as absorptive structures and in other aspects of leaf ecophysiology. We combine anatomical and ecophysiological data to evaluate how trichomes affect leaf gas exchange and water balance during drought. We studied two congeneric species with pubescent leaves which co‐occur in Brazilian Caatinga: Croton blanchetianus (dense trichomes) and Croton adenocalyx (sparse trichomes). We found a novel foliar water uptake (FWU) pathway in C. blanchetianus composed of stellate trichomes and underlying epidermal cells and sclereids that interconnect the trichomes from both leaf surfaces. The water absorbed by these trichomes is redistributed laterally by pectin protuberances on mesophyll cell walls. This mechanism enables C. blanchetianus leaves to absorb water more efficiently than C. adenocalyx. Consequently, the exposure of C. blanchetianus to dew during drought improved its leaf gas exchange and water status more than C. adenocalyx. C. blanchetianus trichomes also increase their leaf capacity to reflect light and maintain lower temperatures during drought. Our results emphasize the multiple roles that trichomes might have on plant functioning and the importance of FWU for the ecophysiology of Caatinga plants during drought. Summary statement: We describe a novel pathway of foliar water absorption that involves stellate trichomes, sclereids and pectin protuberances that redistribute water inside the leaf. The absorption of dew water through this pathway benefits the ecophysiological performance of Caatinga plants during drought. [ABSTRACT FROM AUTHOR]

In the Mediterranean region, a reduction of annual precipitation and a longer and drier summer season are expected with climate change by the end of the century, eventually endangering forest survival. To cope with such rapid changes, trees may modulate their morpho-anatomical and physiological traits. In the present study, we focused on the variation in leaf gas exchange and different leaf morpho-anatomical functional traits of Quercus pubescens Willd. in summer using a long-term drought experiment in natura consisting of a dynamic rainfall exclusion system where trees have been submitted to amplified drought (AD) (~−30% of annual precipitation) since April 2012 and compared them with trees under natural drought (ND) in a Mediterranean forest. During the study, we analyzed net CO2 assimilation (An), stomatal conductance (gs), transpiration (E), water-use efficiency (WUE), stomatal size and density, density of glandular trichomes and non-glandular trichomes, thickness of the different leaf tissues, specific leaf area and leaf surface. Under AD, tree functioning was slightly impacted, since only An exhibited a 49% drop, while gs , E and WUE remained stable. The decrease in An under AD was regulated by concomitant lower stomatal density and reduced leaf thickness. Trees under AD also featured leaves with a higher non-glandular trichome density and a lower glandular trichome density compared with ND, which simultaneously limits transpiration and production costs. This study points out that Q. pubescens exhibits adjustments of leaf morpho-anatomical traits which can help trees to acclimate to AD scenarios as those expected in the future in the Mediterranean region. [ABSTRACT FROM AUTHOR]

Sesquiterpene lactones (STLs) are bitter tasting plant specialized metabolites derived from farnesyl pyrophosphate (FPP) that contain a characteristic lactone ring. STLs can be found in many plant families that are distantly related to each other and outside the plant kingdom. They are especially prevalent in the plant families Apiaceae and Asteraceae, the latter being one of the largest plant families besides the Orchidaceae. The STL diversity is especially large in the Asteraceae, which made them an ideal object for chemosystematic studies in these species. Many STLs show a high bioactivity, for example as protective compounds against herbivory. STLs are also relevant for pharmaceutical applications, such as the treatment of malaria with artemisinin. Recent findings have dramatically changed our knowledge about the biosynthesis of STLs, as well as their developmental, spatial, and environmental regulation. This review intents to update the currently achieved progress in these aspects. With the advancement of genome editing tools such as CRISPR/Cas and the rapid acceleration of the speed of genome sequencing, even deeper insights into the biosynthesis, regulation, and enzyme evolution of STL can be expected in the future. Apart from their role as protective compounds, there may be a more subtle role of STL in regulatory processes of plants that will be discussed as well. [ABSTRACT FROM AUTHOR]

Salt bladders and salt glands of recretohalophytes are specific salt-secreting structures evolving from trichomes that allow plants to adapt to extreme environmental conditions (such as salinity or drought) by precise regulation of the salt load in metabolically active leaf tissues. The knowledge of the process by which these structures are formed and operate may provide a blueprint for introducing them into cultivated crops thus creating climate-resilient genotypes. This review summarizes the recent progress in understanding mechanisms involved in the development and operation of salt bladders and glands, at physiological, molecular, and genetic levels. We show that these processes differ depending on the anatomical structure of glands (unicellular vs bi-cellular vs multicellular), as well as between salt glands and bladders. We also show that recretohalophytes with different types of salt glands may have different trichome development. We discuss new evidence for the role of vesicular transport in salt secretion and highlight the importance of multi-omics in understanding mechanisms of salt secretion and sequestration in epidermal bladder cells, and their contribution to salinity stress tolerance in plants. [ABSTRACT FROM AUTHOR]

Premise: Previous studies have suggested a trade‐off between trichome density (Dt) and stomatal density (Ds) due to shared cell precursors. We clarified how, when, and why this developmental trade‐off may be overcome across species. Methods: We derived equations to determine the developmental basis for Dt and Ds in trichome and stomatal indices (it and is) and the sizes of epidermal pavement cells (e), trichome bases (t), and stomata (s) and quantified the importance of these determinants of Dt and Ds for 78 California species. We compiled 17 previous studies of Dt–Ds relationships to determine the commonness of Dt–Ds associations. We modeled the consequences of different Dt–Ds associations for plant carbon balance. Results: Our analyses showed that higher Dt was determined by higher it and lower e, and higher Ds by higher is and lower e. Across California species, positive Dt–Ds coordination arose due to it–is coordination and impacts of the variation in e. A Dt–Ds trade‐off was found in only 30% of studies. Heuristic modeling showed that species sets would have the highest carbon balance with a positive or negative relationship or decoupling of Dt and Ds, depending on environmental conditions. Conclusions: Shared precursor cells of trichomes and stomata do not limit higher numbers of both cell types or drive a general Dt–Ds trade‐off across species. This developmental flexibility across diverse species enables different Dt–Ds associations according to environmental pressures. Developmental trait analysis can clarify how contrasting trait associations would arise within and across species. [ABSTRACT FROM AUTHOR]

Main conclusion: Understanding surface defenses, a relatively unexplored area in rice can provide valuable insight into constitutive and induced defenses against herbivores. Plants have evolved a multi-layered defense system against the wide range of pests that constantly attack them. Physical defenses comprised of trichomes, wax, silica, callose, and lignin, and are considered as the first line of defense against herbivory that can directly affect herbivores by restricting or deterring them. Most studies on physical defenses against insect herbivores have been focused on dicots compared to monocots, although monocots include one of the most important crops, rice, which half of the global population is dependent on as their staple food. In rice, Silica is an important element stimulating plant growth, although Silica has also been found to impart resistance against herbivores. However, other physical defenses in rice including wax, trichomes, callose, and lignin are less explored. A detailed exploration of the morphological structures and functional consequences of physical defense structures in rice can assist in incorporating these resistance traits in plant breeding and genetic improvement programs, and thereby potentially reduce the use of chemicals in the field. This mini review addresses these points with a closer look at current literature and prospects on rice physical defenses. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

spraying 100 µM melatonin on the plants challenged with individual or combined drought and HT stress showed a significant increase in total chlorophyll content [drought: 16%, HT: 14%, and drought+HT: 11%], Fv/Fm [drought: 16%, HT: 15%, and drought+HT: 13%], relative water content [drought: 10%, HT: 2%, and drought +HT: 8%], and proline [drought: 26%, HT: 17%, and drought+HT: 14%] compared with their respective stress control. Additionally, melatonin positively influenced the stomatal and trichome characteristics compared with stress control plants. Also, the osmotic adjustment was found to be significantly increased in the melatonin-sprayed plants, which, in turn, resulted in an increased number of fruits, fruit set percentage, and fruit yield. Moreover, melatonin spray also enhanced the quality of fruits through increased lycopene content, carotenoid content, titratable acidity, and ascorbic acid content, compared with the stress control. Overall, this study highlights the usefulness of melatonin in effectively mitigating the negative effects of drought, HT, and drought+HT stress, thus leading to an increased drought and HT stress tolerance in tomato. [ABSTRACT FROM AUTHOR]

Cleistogamy is a type of self-pollination that relies on the formation of a stigma-enclosing floral structure. We identify three homeodomain-leucine zipper IV (HD-Zip IV) genes that coordinately promote the formation of interlocking trichomes at the anther margin to unite neighboring anthers, generating a closed anther cone and cleistogamy (flower morphology necessitating strict self-pollination). These HD-Zip IV genes also control style length by regulating the transition from cell division to endoreduplication. The expression of these HD-Zip IV genes and their downstream gene, Style 2.1, was sequentially modified to shape the cleistogamy morphology during tomato evolution and domestication. Our results provide insights into the molecular basis of cleistogamy in modern tomato and suggest targets for improving fruit set and preventing pollen contamination in genetically modified crops. [ABSTRACT FROM AUTHOR]

Background: The present study deals with the detailed pharmacognostic investigation of Sidhha single drug, the stem of Cissus vitiginea L. It is a climber that belongs to the family 'Vitaceae' with a pantropical distribution throughout India and Sri Lanka. In dried form, identification of the specific plant is difficult at present due to the lack of authentic pharmacognostic data related to this specific plant part. Materials and Methods: In order to prevent the adulteration of medicinal components, the stem of C. vitiginea was subjected to different pharmacognostic studies, physicochemical analysis, FT-IR and HPTLC fingerprinting. Results and Discussion: In the microscopical studies, the unique and elaborated anatomical structure is detailed with evidence of powder microscopic characters like trichomes, elongated fibres, raphide sacs, acicular crystals and different arrangements like xylem vessels with perforation plates observed. The results from the HPTLC fingerprint scanned at wavelengths 254 nm, 366 nm, and 575 nm for alcohol extract of stem of C. vitiginea L. confirmed the presence of different phytoconstituents revealed by the FT-IR analysis. Conclusion: All the pharmacognostic characters and physicochemical parameters of stem of C. vitiginea L. could be useful in the identification and standardization of a crude drug. [ABSTRACT FROM AUTHOR]

The incidence of Hop latent viroid (HLVd) affecting cannabis plants in licenced production facilities in Canada during 2020–2023 was determined by RT-PCR analyses of 15 947 samples from nine provinces. Positive detection ranged from 5.3% to 92% of samples submitted, depending on province and year of sampling. The average country-wide HLVd infection incidence was 25.6%. Symptoms on affected plants varied with plant growth stage, and ranged from asymptomatic to mild leaf curl and mottling on stock (mother) plants and on vegetative plants, to extreme stunting and reduced inflorescence development on flowering plants. All symptomatic and some asymptomatic plants contained a 256 nucleotide RNA fragment with 100% sequence homology to HLVd from GenBank. The viroid was detected in various tissues of stock, vegetative, and flowering plants, including the uppermost leaves, at middle and lower positions in the canopy, and in the roots. The incidence of infection varied with the cannabis genotype. Flowering plants displayed yellowing or darkening of inflorescence leaves surrounding the pistillate flowers. Reductions of 12–42% in inflorescence stem lengths, fresh weights, and plant heights were observed in infected plants compared to noninfected plants, depending on the genotype. Levels of tetrahydrocannabinol (THC) and terpenes in diseased inflorescences were also significantly lower. The development of glandular trichomes which produce and store cannabinoids and terpenes was greatly reduced by HLVd infection. The affected trichomes had shorter stalk lengths and smaller glandular head sizes, and appeared shrivelled upon drying of the inflorescences. Hop latent viroid poses a significant economic threat to the cannabis industry. [ABSTRACT FROM AUTHOR]

In this work, we investigated aroma volatiles emanated by dry roots, stems, leaves, flowers, and fruits of Cardaria draba (L.) Desv. growing wild in Tunisia and its aerial part essential oils (EOs) composition. A total of 37 volatile organic compounds (96.7%-98.9%) were identified; 4 esters, 4 alcohols, 7 hydrocarbons, 12 aldehydes, 5 ketones, 1 lactone, 1 organosulfur compound, 2 organonitrogen compounds, and 1 acid. The hydrocarbons form the main group, representing 49.5%-84.6% of the total detected volatiles. The main constituent was 2,2,4,6,6-pentamethylheptane (44.5%-76.2%) reaching the highest relative percentages. Forty-two compounds were determined in the two fractions of EOs, representing 98.8% and 97.2% of the total oil composition, respectively. The principal components were hexadecanoic acid (34.6%), 6-methyl-5-hepten-2-one (18.3%), decanal (15.0%), 6,10,14-trimethyl2-pentadecanone (13.2%), and n-pentacosane (13%). Micromorphological details of the leaf and stem epidermis using light microscopy revealed polygonal cells with sinuous walls in the adaxial and abaxial leaf surfaces and nearly rectangular and long ones with linear and thick walls for the stem epidermis. The stomata complexes were anisocytic in the leaf epidermis and mainly anisocytic and rarely paracytic in the stem epidermis. Non-glandular trichomes were unbranched and long with an acute apex or short with a convex apex. The glandular ones were identified for the first time in this species. They were short-stalked with a large secretory head. The highest stomatal index (17.02%) was recorded in the abaxial leaf surface. The identification of headspace volatiles and essential oil compounds can be used to characterize this species, and the various epidermis micromorphological features are very useful for biosystematics taxonomic studies within Brassicaceae. [ABSTRACT FROM AUTHOR]

Sesquiterpene lactone artemisinin is one of the main agents used to treat malaria. Artemisinin is produced in the glandular secretory trichomes (GSTs) of Artemisia annua. The plant hormones and metabolic pathways regulate the artemisinin content of A. annua. It was possible to examine the functions of auxin, an important plant hormone, in the development of GSTs in A. annua by enhancing the expression of iaaM, which encodes a tryptophan monooxygenase involved in the biosynthesis of auxin. Additionally, the effects of co-overexpression of aldehyde dehydrogenase 1 (ALDH1), P450 monooxygenase (CYP71AV1), and iaaM on the density, length, and width of GSTs and the contents of artemisinin were further investigated. Results indicated that overexpression of iaaM might increase the density, length, and width of GSTs by enhancing auxin biosynthesis. This study also proved the key regulatory role of ALDH1 in the biosynthesis of artemisinin. Moreover, co-overexpression of ALDH1, CYP71AV1, and iaaM successfully increased the density, length, and width of GSTs and improved the artemisinin content in A. annua. Therefore, we established a theoretical basis for modifying artemisinin accumulation in this study by regulating the expression of auxin and artemisinin synthesis-related genes using a metabolic engineering method. [ABSTRACT FROM AUTHOR]

The experimental trials were conducted at Agronomy farm S. K. N. College of Agriculture, Jobner (Rajasthan) during kharif 2019 to identify the infestation of major insect pests of sesame (leaf roller and capsule borer, leafhopper and whitefly). Ten sesame varieties were screened to know their response on the basis of morphometric and biochemical characters. The morphological characters of plant showed that the variety RT-346, which had more number of leaves, branches, capsules per plant and number of trichomes per mm² was found least susceptible for the leaf roller and capsule borer, leafhopper and whitefly population. Whereas the variety RT-46 was found to be most susceptible, which had less trichomes than the variety RT-346. Thus, the morphometric characters like number of leaves per plant, number of branches per plant, number of capsules per plant and trichome density per mm², showed a negative correlation with the mean population of leaf roller and capsule borer, leafhopper and whitefly population in sesame. The total phenols had a negative and significant correlation, while free amino acids, total soluble sugars, protein content and chlorophyll had positive and significant correlation with leaf roller and capsule borer, leafhopper and whitefly population. [ABSTRACT FROM AUTHOR]