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17 recordsLinked to original sources
PubMed2025

The SlGRAS9-SlMYC1 regulatory module controls glandular trichome formation and modulates resilience to pest in tomato.

Trichomes of aerial plant organs contribute to adaptive responses to abiotic and biotic stresses. In horticultural plants, increasing glandular trichome density is an effective breeding strategy to enhance resistance to herbivores through promoting the capacity to produce specialized metabolites. The regulatory mechanisms controlling multicellular trichome formation are only partially understood. In this study, we reveal that SlGRAS9 and SlMYC1 transcription factors form a regulatory module controlling glandular trichome formation in multiple tissues. Knockout of SlGRAS9 or overexpression of SlMYC1 in tomato leads to an increased number of type VI glandular trichomes and to higher terpenoid accumulation in leaves, petals, sepals, and fruits. Conversely, knockout of SlMYC1 results in reduced type VI glandular trichomes number and terpenoid levels. Promoter-binding and genetic interaction experiments revealed that SlGRAS9 negatively regulates the transcription of SlMYC1, indicating that the regulation of glandular trichome formation by SlGRAS9 is dependent, at least partly, on SlMYC1. Consistently, both SlGRAS9 knockout and SlMYC1 overexpression result in higher tolerance of tomato plants to spider mites and aphids. In addition to adding some of the missing components to the mechanisms controlling formation of type VI glandular trichome, our findings also uncover new targets for breeding strategies aimed at improving crop protection against pest invasion, thus ensuring crop yield resilience to climate change.

Trichomes↗
PubMed2026

Comprehensive transcriptomic analysis of BjGL1-knockout Brassica juncea: novel insights into leaf trichome formation.

Brassica juncea is a common cruciferous crop, which can be used not only for oil extraction but also as condiments and medicinal materials. It is regarded by both traditional medicine and modern nutrition science as a food with combined dietary and health promoting value. Leaf trichomes are hair-like structures differentiated from epidermal cells and constitute an important barrier against biotic and abiotic stresses, playing a crucial role in enhancing plant resistance and thus possessing significant scientific relevance. In this study, the phenotype and gene editing site of BjA06.GL1 and BjB02.GL1 knockout mustard T1 generation plants were identified. Then, RNA sequencing was performed to compare the leaf transcriptome profiles between gene-edited lines and wild-type plants, with the aim of elucidating the molecular regulatory mechanisms by which BjGL1 controls leaf trichome development and associated biological processes in mustard. The sequencing data showed that, on average, 90.64% of the reads uniquely aligned to the Brassica juncea (Xuecai) reference genome. A total of 4,604 differentially expressed genes were identified in this study. Compared with the gene knockout mutant, 1,831 genes were significantly upregulated and 2,773 genes were downregulated in mustard leaves with trichomes. The differentially expressed genes were mainly enriched in pathways related to cytochrome P450 (CYP), transporters, environmental adaptation, and plant-pathogen interactions. These pathways are closely associated with secondary metabolite biosynthesis, transmembrane transport, and responses to abiotic stress and pathogen defense. qRT-PCR validation confirmed consistent expression trends of trichome regulatory genes screened from transcriptome data. This study provides an important theoretical basis for elucidating molecular mechanisms potentially contributing to trichome formation in mustard.

Mustard Plant↗
PubMed2026

The DELAYED ABAXIAL TRICHOMES Helitron has dual functions in vegetative and pollen development in Arabidopsis thaliana.

Transposons drive genetic diversity and evolution by altering the genomic landscape over time. Here, we describe DELAYED ABAXIAL TRICHOMES (DAB), a Helitron/RC transposable element in Arabidopsis thaliana that has a role in vegetative phase change and gametogenesis. A genome-wide association study (GWAS) for the timing of abaxial trichome development (an adult leaf trait) in A. thaliana revealed a conserved haplotype of polymorphisms within DAB that delays abaxial trichome production. CRISPR-Cas9-induced deletions of DAB are gametophytic pollen-lethal, indicating that this locus is also required for pollen production. DAB produces 24-nucleotide siRNAs with sequence complementarity to genes involved in embryogenesis, gametogenesis, and seed development. DAB also impacts the expression of ARGONAUTE genes, genes involved in RNA-directed DNA methylation (RdDM), as well as genes in several key genetic pathways. This global effect on gene expression suggests that DAB may have functions beyond those identified in this study.

Arabidopsis↗
PubMed2026

Insights into glandular trichome biology from analysis of organ-specific gene expression programmes in cannabis, hop and tomato.

Glandular trichomes (GTs) are epidermal outgrowths in which diverse specialised (secondary) metabolites are synthesised and stored. Cannabis (Cannabis sativa L.) and its close relative hop (Humulus lupulus L.) have pharmaceutical and industrial significance due to the presence of these metabolites in their GTs. We examined the conservation or divergence of the specific transcriptional programmes underlying GT biology. To achieve this, we generated transcriptome atlases of trichomes, flower, leaf, stem and root for cannabis, hop and tomato. We found that 12.9, 10.1 and 16.8% of cannabis, hop and tomato genes, respectively, were expressed organ/tissue specifically across all organs/tissues. Transcription factors (TFs) on average accounted for 7.5% of the organ-specific transcriptome and likely regulate organ-specific functions. We also conducted weighted gene co-expression network analysis and gene regulatory network (GRN) analysis to identify key regulators of GT function across the species and validated our predictions by DNA affinity purification sequencing for a subset of the cannabis and tomato GT TFs. The GRNs specific to cannabis or hop GTs were enriched for TFs and target genes associated with specialised metabolism, reflecting their species-specific nature. Conversely, the shared GRN components (identified via orthology analysis) were involved in highly conserved processes, such as flavonoid biosynthesis, solute transport and metabolite storage. Together, these GRNs and the associated transcriptome atlases are valuable resources to improve our knowledge of GT function and organ-specific genome regulation.

Solanum lycopersicum↗
PubMed1979

Soil stabilization by a prokaryotic desert crust: implications for Precambrian land biota.

A cyanophyte dominated mat, desert crust, forms the ground cover in areas measuring hundreds of square meters in Utah and smaller patches in Colorado. The algal mat shows stromatolitic features such as sediment trapping and accretion, a convoluted surface, and polygonal cracking. Sand and clay particles are immobilized by a dense network of filaments of the two dominating cyanophyte species, Microcoleus vaginatus and M. chthonoplastes, which secrete sheaths to which particles adhere. These microorganisms can tolerate long periods of desiccation and are capable of instant reactivation and migration following wetting. Migration occurs in two events: 1. immediately following wetting of dry mat, trichomes are mechanically expelled from the sheath as it swells during rehydration, and 2. subsequently, trichomes begin a self-propelled gliding motility which is accompanied by further production of sheath. The maximum distance traveled on solid agar by trichomes of Microcoleus vaginatus during a 12 hour period of light was 4.8 cm. This corresponds to approximately 500 times the length of the fastest trichome, and provides a measure of the potential for spreading of the mat in nature via the motility of the trichomes. Dehydration resistence of the sheath modifies the extracellular environment of the trichomes and enables their transition to dormancy. Following prolonged wetting and evaporative drying of the mat in the laboratory, a smooth wafer-like crust is formed by the sheaths of Microcleus trichomes that have migrated to the surface. Calcium carbonate precipitates among the algal filaments under experimental conditions, indicating a potential for mat lithification and fossilization in the form of a caliche crust. It is suggested that limestones containing tubular microfossils may, in part, be of such an origin. The formation of mature Precambrian soils may be attributable to soil accretion, stabilization, and biogenic modification by blue-green algal land mats similar to desert crust.

Cyanobacteria↗
PubMed1977

Influence of electric fields on photophobic reactions in blue-green algae.

The effect of external electric fields on photo-accumulations of Phormidium uncinatum in light traps has been studied. 1. In direct current fields the phobic reaction of trichoms leaving the light field is not impaired if a voltage of 2.5 V is not exceeded. With voltages between 3 and 7 V the trichoms are motile, but phobic reactions are cancelled, provided the organisms are oriented more or less parallel to the electric field lines. Higher voltages cause the algae to die within minutes. 2. Only alternating current fields of very low frequencies (less than or equal 10(-3) Hz) have similar effects. Sine waves are more effective than triangular ones, but less than square waves. A hypothesis is proposed according to which sensory transduction of photophobic reactions in blue-green algae is mediated by changes in the endogenous membrane potential. This potential might be interfered with by the application of an external electric field, thus inhibiting photophobic reactions.

Cyanobacteria↗
PubMed1977

On the morphology and ultrastructure of the cell wall of Spirulina platensis.

The cell wall of the blue-green alga Spirulina platensis was studied with the electron microscope using ultra-thin sectioning, shadowing, carbon-replication or freeze-etching techniques for specimen preparation. The cell wall could be resolved into four layers, L-I through L-IV. The L-I and L-III layers contain fibrillar material. The septum is a three-layered wall: an L-II layer sandwiched between L-I layers. The shape in vitro of isolated septa might be an artifact due to the preparation technique used. Certain structural properties of the septum seem to allow tangential stretching; they might be reflected in the flexible gliding mobility of Spirulina species. The outer, L-IV layer contains material longitudinally arranged along the trichome axis.

Cell Wall↗
PubMed1979

The ultrastructure of Spirulina platensis in relation to temperature and light intensity.

The ultrastructure of Spirulina platensis, a cyanobacterium with a helical morphology, has been studied in relation to temperature and light intensity. An increase in temperature gives rise to a more tightly coiled trichome, an increase in sheath material formation and a decrease in cyanophycin (above 17 degrees C) and polyglucan (above 20 degrees C) granule concentration. An increase in light intensity leads to an increase in gas vesicle concentration while the phycobilisome content decreases. Furthermore, cylindrica bodies have been observed with a somewhat different ultrastructure from those found in other species of cyanobacteria. The occurrence, size and ultrastructure of polyhedral bodies, photosynthetic lamellae, mesosomes, lipid deposits and an unknown kidney-shaped inclusion in relation to temperature and light intensity are described.

Cell Wall↗
PubMed1975

Ragged-red fibers. A biochemical and morphological study.

Histochemical, ultrastructural and biochemical studies were performed on muscle biopsy specimens from a 30-year-old man with proximal limb weakness. Modified Gomori trichome stains of anterior tibial muscle revealed accumulations of red-staining material in the subsarcolemmal and intermyofibrillar regions of virtually every fiber (ragged-red fibers); these accumulations were rich in oxidative enzymes. Electron microscopy of this muscle showed that the red-staining areas consisted of large collections of abnormal-appearing mitochondria. Mitochondria isolated from the quadriceps muscle showed lack of respiratory control with alpha-glycerophosphate as substrate. However, the lack of respiratory control with alpha-glycerophosphate must be interpreted with caution since the quadriceps muscle was severely degenerated, and biochemical alterations of mitochondria may occur secondary to muscle degeneration itself. Nevertheless, this is the second reported case of lack of respiratory control with alpha-glycerophosphate in a patient with ragged-red fibers. Further interpretation of this defect and its significance must await more studies to determine whether this muscle mitochondrial abnormality is a common finding in the disorders in which ragged-red fibers are encountered.

Adenosine Triphosphatases↗
PubMed2026

Yorkie/Scalloped-OVOL-Rac1 axis controls insect wing development by promoting cell proliferation.

The regulation of organ size is a fundamental question in developmental biology, and insect wings provide a powerful model for elucidating the genetic mechanisms underlying morphogenesis. Although the conserved Hippo signaling pathway plays a central role in controlling tissue growth, its precise regulatory network during wing development remains incompletely understood. Here, we identify the zinc finger transcription factor OVOL as a critical mediator of Hippo signaling in insect wing development. We indicate that OVOL is essential for normal wing formation in both Locusta migratoria and Drosophila melanogaster, regulating cell proliferation and trichome patterning. Through transcriptomic analysis and functional validation, we further identify the small GTPase Rac1 as a key downstream effector of OVOL that promotes proliferative growth. Moreover, we find that OVOL expression is directly activated by the Yorkie/Scalloped (Yki/Sd) complex, the core transcriptional effector of the Hippo pathway, without forming a feedback loop. This regulation is mediated through a specific Sd-binding motif (GATAA) within the OVOL promoter. Importantly, Yki/Sd-induced Rac1 expression is dependent on OVOL. Collectively, our findings establish the Yorkie/Sd-OVOL-Rac1 pathway that governs insect wing development by promoting cell proliferation, providing mechanistic insights into organ size regulation in animals.

Cell proliferation↗
PubMed2026

The chemical landscape of plant surface metabolites: Acylsugars as models of ecological function and structural diversity.

Plants produce a multifunctional assortment of specialized metabolites that play important roles in defense, environmental adaptation, and ecological interactions. Among these compounds, acylsugars, nonvolatile metabolites produced primarily in glandular trichomes of Solanaceae species, have emerged as informative model systems for understanding plant surface chemistry. Differences in acyl chain length, branching pattern, saturation, and attachment position generate extensive chemical diversity that influences herbivore deterrence, pathogen resistance, and the physicochemical properties of leaf surfaces. Recent advances in analytical chemistry, particularly liquid chromatography-ion mobility-tandem mass spectrometry (LC-IM-MS/MS), have greatly improved the ability to separate structurally related acylsugar isomers and characterize metabolite complexity at high resolution. When integrated with genomics, transcriptomics, and emerging spatial metabolomics approaches, these analytical tools provide new insights into acylsugar biosynthesis, pathway regulation, evolutionary diversification, and ecological function across plant species. This review positions acylsugars, particularly those of Solanum species, as model systems for understanding how structural diversity, spatial localization, and specialized metabolism shape ecological and physiological function at plant surfaces. We examine acylsugar structural diversity, biosynthetic pathways, ecological and physiological functions, and interactions with environmental and atmospheric processes. Major challenges, including extensive isomeric complexity, incomplete pathway characterization, and difficulties linking chemical structure to biological function, are discussed alongside emerging opportunities in integrative omics, crop improvement, sustainable pest management, and environmental monitoring. Overall, acylsugars provide a powerful model for linking molecular structure, spatial localization, and ecological function, offering broader insight into how specialized metabolism shapes plant adaptation, defense, and environmental interactions.

Acylsugars↗
PubMed1977

Myopathies with abnormal mitochondria. A clinical, histological, and electrophysiological study.

Among 135 consecutive patients with myopathy, 17 showed abnormalities in the mitochondria of muscle. In eight of these patients the abnormalities were demonstrated by electron microscopy. In all patients Gömöri trichome stain showed red masses at the sites of the mitochondria and diformazan deposits when stained for mitochondrial enzymes. The patients could be divided into three groups: i) Nine patients had weakness of the extra-ocular muscles, either alone or associated with weakness of skeletal muscles and non-muscular signs. One patient with the oculo-cranio-somatic syndrome had two affected sibs. ii) Four patients had a facioscapulohumeral distribution of weakness. Three (two sisters and a maternal aunt) were in the same family, and the fourth patient had an affected sister. iii) Four patients were clinically heterogeneous. When mitochondrial alterations were the only pathological change in many fibers in a muscle, they were most often associated with an ocular or oculo-cranio-somatic syndrome. Electromyography showed changes indicating or suggestive of myopathy in all but one patient. There was a discrepancy between severe changes in the EMG and nearly normal fibers by hematoxylin and eosin and van Gieson stains. Serum creatine kinase was increased in 10 of 17 patients, in most 2-4 times the upper limit of normal.

Action Potentials↗
PubMed1977

A modified techinque to study leaf epidermis in Triticeae.

A rapid modified method is described to study stomata and other epidermal features without elaborate processing. The preparations are semipermanent and permit spatial relationship studies of both leaf surfaces from the same field. The cleared preparations are optically sectioned with brightfield or Nomarski interference contrast techniques without staining for contrast. The technique permits superior tissue resolution, clarity, minimal distortion of sections, and preservation of trichomes. The method is applicable to all species of Triticeae.

Histological Techniques↗
PubMed1975

Histochemical studies in stomatal apparatus of Phaseolus mungo Linn. I. Localization of enzymes and structural material.

In the present investigations, the localization of several enzymes (Acid Phosphatase, Peroxidase, succinic dehydrogenase, Phosphorylase, alkaline phosphatase, ATP-ase) and other substances in the guard and subsidiary cells as well as trichomes of the leaves of Phaseolus mungo, was carried out. Attempts were also made to follow the sequence of developmental stages starting with meristemoids and culminating in differentiated structures. The basic information thus obtained is used in interpreting the developmental physiology of stomatal differentiation as well as their cellular organisation. Histochemical observations made in the present studies are compared with the electron microscopical observations of Whatley (1972). It is proposed that mitochondria played a basic role in the functioning of the guard cells. The present studies also demonstrated activity of acid phosphatase in the guard cells and was localized in spherosomes. The latter varied in the activity for acid phosphatase and was dependent on the turgid level of the cell. Interestingly, enough localization of phosphatase could only be observed in spherosomes when the osmotic pressure in the cell was relatively low, once the osmotic pressure increased, the activity disappeared.

Acid Phosphatase↗
PubMedDate not supplied

[Cytomorphology of the lipid inclusions of Caryophanon during its growth on an agarized medium].

The cytomorphology of lipid inclusions of Caryophanon latum and Caryophanon tenue was studied in the course of their growth on a solid medium. The paper presents a detailed scheme and microphotographs showing cytomorphological changes in the inclusions of the cultures under study. Staining of the preparations with the lipophilic dye Sudan Black B revealed two types of sudanophilic granules which varied in their location within trichomes, the time at which they appeared in bacteria, and their behaviour toward solvents. These lipid inclusions of Caryophanon are mainly represented by the polymer poly-beta-hydroxybutyric acid.

Agar↗
PubMedDate not supplied

[Fine structure of Chloroflexus aurantiacus var. mesophilus (nom. prof.) grown in the light under aerobic and anaerobic conditions].

The fine structure was studied in two mesophilic strains of Chloroflexus aurantiacus var. mesophilus (nom. prof.): KN-4 and BR-1. Trichomes are covered with a mucous fibrillar sheath which is more developed in the KN-4 strain. Photosynthetic structures, "chlorobium-vesicles", are located at the periphery of the cells of both strains. The structure of the cell was is typical of gram-negative microorganisms. By their electron density and dimensions, inner cytoplasmic structures are identified as poly-beta-hydroxybutyric acid, polyphosphates, and polysaccharides. When the strain BR-I was grown in aerobic conditions in the light, "chlorobium-vesicles" were not synthesized and intracytoplasmic membranes were represented by small tubular-vesicular invaginations. When the cells were grown under anaerobic conditions in the lgiht, numerous "chlorobium-vesicles" were formed, and additional large vesicular membrane systems appeared; these systems occupied over 20 per cent of the cell volume. Possible relationship between the membrane structures and the synthesis of bacteriochlorophyll a and c is discussed.

Aerobiosis↗