Trichome Density Research Articles

Impact of Cassava Cultivars on Stylet Penetration Behavior and Settling of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)

This study investigates the settling preferences and feeding behavior of the Bemisia tabaci whitefly on six cassava cultivars using electrical penetration graph techniques. Six distinct electrical penetration graph waveforms—non-probing, stylet pathway, phloem salivation, phloem ingestion, intracellular puncture, and xylem feeding—were identified and analyzed. Significant differences in the frequency and duration of these waveforms were observed among the cassava cultivars. The whiteflies spent the majority of their time in the non-probing phase, particularly on the Huaybong 80, Kasetsart 50, Rayong 9, and Rayong 72 cultivars. CMR-89 cultivar exhibited higher total probe durations in the phloem salivation and ingestion waveforms, suggesting a greater potential for transmission of the Sri Lankan cassava mosaic virus. The study also examined trichome density and size across the cassava cultivars, revealing that CMR-89 had the highest density and small trichomes, while Huaybong 80 had the lowest density. Trichome characteristics significantly impacted whitefly behavior: larger trichomes were negatively correlated with whitefly settling, whereas higher trichome density was positively correlated with longer settling durations. These findings indicate that trichome-based resistance mechanisms are crucial in whitefly deterrence. Overall, the results suggest that cultivars with lower trichome density and larger trichomes are more resistant to whitefly infestation and subsequent Sri Lankan cassava mosaic virus transmission. These insights are valuable for cassava breeding programs focused on enhancing pest resistance, highlighting the importance of trichome characteristics in developing more resilient cassava varieties.

Two novel alleles of the MYB transcription factor BjA06.GL1 and BjB02.GL1 control leaf trichomes and enhance resistance to aphids in Brassica juncea

Abstract Leaf trichome formation is a very important agronomic trait as it confers resistance to biotic and abiotic stresses, but the causal genes involved in this process in B. juncea remain largely unexplored. In this study, we first characterized the haplotypes of BjB02.GL1 among different inbred lines with leaf trichomes or glabrous leaves. A comparative analysis of the number and density of leaf trichomes between the two mustard inbred lines was then performed. BSA analysis of leaves with trichomes and glabrous pools from the F2 segregating population mapped the candidate genes on Chr.A06 and Chr.B02. Two candidate genes, BjA06.GL1 and BjB02.GL1, were subsequently cloned. After sequence alignment of the BjGL1 genes, both SNPs and indel were identified in the BjA06.GL1 and BjB02.GL1 genes. And qRT–PCR analysis further confirmed that both the BjA06.GL1 and BjB02.GL1 genes were more highly expressed in leaves with trichomes than in glabrous leaves. As the leaf size increased, the leaf trichome density decreased. Gene editing of both BjA06.GL1 and BjB02.GL1 changed the leaf trichome to a glabrous leaf phenotype in mustard. In addition, plants with leaf trichomes presented greater resistance to aphids. Taken together, our results revealed that both BjA06.GL1 and BjB02.GL1 positively regulate leaf trichome formation and help increase aphid resistance in mustard. This study provides valuable resources and helps to elucidate the molecular mechanism of leaf trichome formation in B. juncea.

Role of silicon in legume‐insect interactions: Insights from a plant experiencing different levels of herbivory

Abstract Silicon (Si) supplementation can enhance symbiotic functions in some legumes (Fabaceae) with their nitrogen‐fixing rhizobia, such as root nodulation and nitrogen fixation. However, it is still poorly understood how Si influences legume–insect interactions. Here, we investigated how a symbiotic legume responds not only to Si supplementation but also to herbivory treatment with varying infestation levels in two events. We conducted a controlled climate chamber experiment by growing Medicago truncatula plants inoculated with rhizobia. For half of the plants, the soil was kept without Si (−Si), whereas the other half was regularly supplemented with Si (+Si). We then infested the plants with caterpillars of Spodoptera littoralis with 0, 1 or 3 larvae and 0, 1 or 1 larva in single herbivory attack and in double herbivory attack, respectively. To understand plant responses to such treatment combinations, we examined 16 functional traits. Nodule number, nodule fresh mass and nodule leghaemoglobin concentrations were not affected in single attack plants. However, increasing levels of herbivory led to decreases in such measured traits in double attack plants. Foliar C to N ratio increased in single attack plants but decreased in double attack plants with increasing levels of herbivory, indicating contrasting resource allocation. Herbivory did not affect the content of foliar Si, which was higher in +Si than −Si plants. Si and herbivory led to reduced foliar phenolics in double attack plants, suggesting a potential trade‐off between silicification and phenolic production. Si and herbivory led to increased trichome densities in single attack plants, but patterns were less clear in double attack plants. Herbivory but not Si reduced plant biomass with increasing levels of herbivory in double attack plants. Relative growth rates of the caterpillars, as proxy for plant resistance, decreased mainly due to herbivory treatment, when fed on single attack plants. Using a trait‐based approach, we provide novel insights to better understand the response of a legume to Si supplementation and different herbivory levels and events. We conclude that herbivory predominantly exerts much stronger effects than Si on various plant traits, pointing to a necessity to respond to herbivory by induced defence strategies. Read the free Plain Language Summary for this article on the Journal blog.

Response of the tomato leaf miner Phthorimaea absoluta to wild and domesticated tomato genotypes.

Phthorimaea absoluta, a highly destructive invasive pest, poses a significant threat to tomato production globally. Exploring alternative control methods, such as host plant resistance can contribute to diminish reliance on insecticides and promote sustainable integrated pest management (IPM) practices. Thus, the identification of new P. absoluta-resistant tomato cultivars and potential wild sources for breeding programmes remains imperative. We evaluated the effect of 19 tomato genotypes, comprising 16 domesticated varieties and three wild tomato species, on oviposition output of female P. absoluta, as well as on larval performance under no-choice conditions using detached leaves. We also characterized and quantified glandular and nonglandular trichomes, exploring their potential correlation with the response of P. absoluta to the tomato plants. Generally, fewer eggs were oviposited on domesticated plants, whereas the wild tomatoes Solanum arcanum and S. neorickii and the domesticated tomato Corona F1 impaired larval development. The pest larvae consumed a limited area of leaflets from S. arcanum and S. neorickii compared to other genotypes, leading to the lowest weights in both male and female pupae. All tomato plants exhibited a prevalence of nonglandular over glandular trichomes, except for S. arcanum, which exhibited a higher abundance of glandular trichomes. Although higher trichome density correlated with longer larval settlement on the leaflets, it did not influence female oviposition. Our findings demonstrate that the wild tomatoes S. arcanum and S. neorickii could be considered as potential sources for breeding programmes, and the domesticated Corona F1 could offer IPM options against P. absoluta. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Biophysical and biochemical parameters of Sorghum associated to shoot fly resistance

The sorghum shoot fly, Atherigona soccata (Muscidae: Diptera), represents a significant biotic constraint to sorghum production, leading to considerable yield losses globally. This study aimed to systematically classify sorghum genotypes based on their resistance to A. soccata infestation. A total of 188 genotypes were subjected to rigorous evaluation employing standardized screening methodologies. The analysis revealed substantial variability in resistance levels across the genotypes. Based on damage assessments in field trials, 14 genotypes were selected for further investigation under controlled pot culture conditions. Comprehensive biochemical analyses were conducted on each genotype under both uninfested and infested scenarios. Among the evaluated genotypes, IS 10588 and IS 8380 exhibited high levels of resistance, IS 12787 demonstrated moderate resistance, while TNFS 230 was classified as moderately resistant to A. soccata infestation. Critical morphological and biochemical traits associated with resistance were identified, including trichome density, leaf glossiness, and enzyme activity levels of peroxidase (PO), polyphenol oxidase (PPO), tannins, and phenolic compounds. The study concludes that these morpho-physiological and biochemical characteristics contribute significantly to the resistance mechanisms in sorghum against A. soccata. Thus, these identified genotypes may serve as valuable genetic resources for breeding programs aimed at enhancing resistance to A. soccata in sorghum.

Image-Based Quantitative Analysis of Epidermal Morphology in Wild Potato Leaves.

The epidermal leaf patterns of plants exhibit remarkable diversity in cell shapes, sizes, and arrangements, driven by environmental interactions that lead to significant adaptive changes even among closely related species. The Solanaceae family, known for its high diversity of adaptive epidermal structures, has traditionally been studied using qualitative phenotypic descriptions. To advance this, we developed a workflow combining multi-scale computer vision, image processing, and data analysis to extract digital descriptors for leaf epidermal cell morphology. Applied to nine wild potato species, this workflow quantified key morphological parameters, identifying descriptors for trichomes, stomata, and pavement cells, and revealing interdependencies among these traits. Principal component analysis (PCA) highlighted two main axes, accounting for 45% and 21% of variance, corresponding to features such as guard cell shape, trichome length, stomatal density, and trichome density. These axes aligned well with the historical and geographical origins of the species, separating southern from Central American species, and forming distinct clusters for monophyletic groups. This workflow thus establishes a quantitative foundation for investigating leaf epidermal cell morphology within phylogenetic and geographic contexts.

Interactive effect of biogenic nanoparticles and UV-B exposure on physio-biochemical behavior and secondary metabolism of Artemisia annua L

Biosynthesized silver nanoparticles (AgNPs) are key nanomaterials with unique physio-chemical characteristics and diverse applications. Their strong absorption potential and antibacterial activity make them useful for agriculture, medicine and other industries. AgNPs boost plant growth and metabolism, especially under stress. However, the combined effects of AgNPs and UV-B exposure on plants are unknown. To elucidate the interactive effects of biosynthesized silver nanoparticles (AgNPs) and exposure of ultraviolet B (UV-B) on plant growth and metabolic processes, this study assessed the response of Artemisia annua under controlled in vitro conditions. In total, eight sets of plants were used with the alone/combined treatment of AgNPs and UV-B. For this purpose, spherical and averaged ∼ 31.8 nm in size AaAgNPs were synthesized. The photosynthetic pigments were calculated maximum with the alone treatment of 0.5 mg L−1 AaAgNPs and combined treatment of 0.5 mg L−1 AaAgNPs with 3 h UV-B, respectively. The results evidenced that the co-exposure of AaAgNPs and UV-B led to a significant balance in ROS production of A. annua; as well as improved antioxidative enzyme activity. Fluorescence and scanning electron microscopic (SEM) analysis indicated the enhancement of glandular trichomes (GT) area and density with the combined treatment of AaAgNPs and 3 h UV-B. In accordance with correlation between microscopic GT results, high concentration of artemisinin and up-regulation of related transcripts were found in A. annua plants treated with low concentrations of AaAgNPs and UV-B. Thus, it may be inferred that two distinct plant growth modulators, namely low-concentration biosynthesized AgNPs and short-term UV-B exposure, can enhance the physio-biochemical characteristics and production of secondary metabolites (specially artemisinin) in A. annua synergistically.

Investigation geographic origin of Laurus nobilis L. leaves using FTIR, SEM-EDX, and XRD analysis

Laurus nobilis L. is a polypragmatic plant with high added value. Leaves collected from different regions in the natural state without breeding have different economic values. In this study, the Geographic Origin and Altitude Effects of Laurus nobilis L. leave samples collected from provinces close to each other were investigated. For this purpose, SEM–EDS was used for morphological characterization of leaves, XRD was used for the characterization of inorganic components and FTIR-ATR was used for the identification of functional groups. By SEM analysis in the samples from Zonguldak region, significant differences were observed in the density of trichomes and glandular plumes more dense and also morphological cell sizes were found to be more large then Kastamonu region. In XRD plot, besides the amorphous state, it has seen that the crystal structure is also present in the structure. The effect of different altitudes on the FTIR spectra of the samples collected according to the provinces was also examined, and no significant difference was observed in the peak positions and intensities in the spectra according to the altitudes. Score plot on ranges of 2800–3000 cm-1 and 750–1800 cm−1 allowed origin of the Laurus nobilis L. discrimination. In order to analysis and classify them according to their geographical origin, FTIR data were combined with chemometric methods using PCA and discriminant analysis. PCA analysis explained 88.7% of the variance in the model. When the results of the discriminant analysis were evaluated, 56 of the 72 samples were classified correctly and 77.8% success was achieved. Both analysis showed that there are differences in the response of the same plant species to their presence in different origins. As a result, FTIR analysis allowed possibility the discrimination of Laurus nobilis L. leaves and in this way it is thought to discriminate of examples for other areas.

Host plant suitability for the biological performance of Tetranychus urticae Koch and its predator, Phytoseiulus persimilis Athias-Henriot

The life table parameters provide the most extensive information on the biological features of pests and natural enemies, facilitating the potential employment of biological agents in pest management programs. This study investigated how cucumber, strawberry, eggplant, and tomato plants influence the reproduction and life-table parameters of Tetranychus urticae Koch and its predator, Phytoseiulus persimilis Athias-Henriot under laboratory conditions. It also explored the relationship between these parameters and leaf trichome density and the levels of polyphenol compounds. The mites’ biological properties varied based on the morphological and chemical differences in host plant leaves. Both T. urticae and P. persimilis exhibited higher development and reproduction rates on strawberry and cucumber leaves compared to eggplant and tomato plants. Eggplant leaves had the highest polyphenol content (3826.99 mg/kg), followed by tomato leaves (2406.86 mg/kg). The lowest total amount of polyphenol compounds was (704.34 mg/kg) and (273.743 mg/kg) in strawberry and cucumber leaves, respectively. The life table parameters of P. persimilis significantly differed when it fed on T. urticae that had been reared on strawberry, cucumber, eggplant, and tomato leaves. Overall, the results showed that the net (R0) and gross (GRR) reproductive rates were reduced when the predator preyed T. urticae that had been reared on eggplant and tomato leaves. Consequently, the intrinsic (rm) and finite (λ) rates of increase were affected. As a result, the performance of P. persimilis was negatively affected on these plants. The availability of information on the biological performance of P. persimilis is necessary for promoting biological control implementation.

Genome-wide investigation of WRKY gene family in Lavandula angustifolia and potential role of LaWRKY57 and LaWRKY75 in the regulation of terpenoid biosynthesis.

The WRKY transcription factors are integral to plant biology, serving essential functions in growth, development, stress responses, and the control of secondary metabolism. Through the use of bioinformatics techniques, this research has effectively characterized 207 members of the WRKY family (LaWRKY) present in the entire genome of Lavandula angustifolia. Phylogenetic analysis classified LaWRKYs into three distinct categories based on conserved domains. Collinearity analysis revealed tandem repeats, segmental duplications, and whole genome duplications in LaWRKYs, especially for segmental duplication playing a significant role in gene family expansion. LaWRKYs displayed distinct tissue-specific expression profiles across six different tissues of L. angustifolia. Particularly noteworthy were 12 genes exhibiting high expression in flower buds and calyx, the primary sites of volatile terpenoid production, indicating their potential role in terpenoid biosynthesis in L. angustifolia. RT-qPCR analysis revealed a notable increase in the expression levels of most examined LaWRKY genes in flower buds in response to both intense light and low-temperature conditions, whereas the majority of these genes in leaves were primarily induced by drought stress. However, all genes exhibited downregulation following GA treatment in both flower buds and leaves. Overexpression of LaWRKY57 (La13G01665) and LaWRKY75 (La16G00030) in tobacco led to a reduction in the density of glandular trichomes on leaf surfaces, resulting in changes to the volatile terpenoid composition in the leaves. Specifically, the content of Neophytadiene was significantly elevated compared to wild-type tobacco, while compounds such as eucalyptol, cis-3-Hexenyl iso-butyrate, and D-Limonene were produced, which were absent in the wild type. These findings provide a valuable reference for future investigations into the biological functions of the WRKY gene family in L. angustifolia.

Natural variation at the cotton HIC locus increases trichome density and enhances resistance to aphids.

Plant trichomes are an excellent model for studying cell differentiation and development, providing crucial defenses against biotic and abiotic stresses. There is a well-established inverse relationship between trichome density and aphid prevalence, indicating that higher trichome density leads to reduced aphid infestations. Here we present the cloning and characterization of a dominant quantitative trait locus, HIC (hirsute cotton), which significantly enhances cotton trichome density. This enhancement leads to markedly improved resistance against cotton aphids. The HIC encodes an HD-ZIP IV transcriptional activator, crucial for trichome initiation. Overexpression of HIC leads to a substantial increase in trichome density, while knockdown of HIC results in a marked decrease in density, confirming its role in trichome regulation. We identified a variant in the HIC promoter (-810 bp A to C) that increases transcription of HIC and trichome density in hirsute cotton compared with Gossypium hirsutum cultivars with fewer or no trichomes. Interestingly, although the -810 variant in the HIC promoter is the same in G. barbadense and hirsute cotton, the presence of a copia-like retrotransposon insertion in the coding region of HIC in G. barbadense causes premature transcription termination. Further analysis revealed that HIC positively regulates trichome density by directly targeting the EXPANSIN A2 gene, which is involved in cell wall development. Taken together, our results underscore the pivotal function of HIC as a primary regulator during the initial phases of trichome formation, and its prospective utility in enhancing aphid resistance in superior cotton cultivars via selective breeding.

Combined Effects of Heavy Metal and Simulated Herbivory on Leaf Trichome Density in Sunflowers

Trichomes play a key role in both heavy metal tolerance and herbivory defense, and both stressors have been shown to induce increased trichome density. However, the combined effect of these stressors on trichome density in general, and specifically on metal-hyperaccumulating plants, has yet to be examined. The aim of this study was to test the effect of cadmium availability and herbivory on leaf trichome density and herbivore deterrence in the metal hyperaccumulator Helianthus annuus. To test this, H. Annuus plants were grown in control pots or pots inoculated with 10 mg/kg cadmium and were subjected to either no herbivory or simulated herbivory using mechanical damage and foliar jasmonic acid application. Herbivore deterrence was tested in a feeding assay using Spodoptera littoralis caterpillars. Interestingly, while the trichome density of H. annuus increased by 79% or 53.5% under high cadmium availability or simulated herbivory, respectively, it decreased by 26% when the stressors were combined. Furthermore, regardless of cadmium availability, simulated herbivory induced a 40% increase in deterrence of S. littoralis. These findings suggest that the combination of metal availability and herbivory might present excessive stress to hyperaccumulators. Moreover, they suggest that the risk of metal bioaccumulation in phytoremediation can be reduced by simulated herbivory.

Effects of Corm Treatment with Cold Plasma and Electromagnetic Field on Growth and Production of Saffron Metabolites in Crocus sativus.

Crocus sativus L. is a widely cultivated traditional plant for obtaining dried red stigmas known as "saffron," the most expensive spice in the world. The response of C. sativus to pre-sowing processing of corms with cold plasma (CP, 3 and 5 min), vacuum (3 min), and electromagnetic field (EMF, 5 min) was assessed to verify how such treatments affect plant performance and the quality and yield of herbal raw materials. The results show that applied physical stressors did not affect the viability of corms but caused stressor-dependent changes in the kinetics of sprouting, growth parameters, leaf trichome density, and secondary metabolite content in stigmas. The effect of CP treatment on plant growth and metabolite content was negative, but all stressors significantly (by 42-74%) increased the number of leaf trichomes. CP3 treatment significantly decreased the length and dry weight of flowers by 43% and 60%, respectively, while EMF treatment increased the length of flowers by 27%. However, longer CP treatment (5 min) delayed germination. Vacuum treatment improved the uniformity of germination by 28% but caused smaller changes in the content of stigma compounds compared with CP and EMF. Twenty-six compounds were identified in total in Crocus stigma samples by the HPLC-DAD method, including 23 crocins, rutin, picrocrocin, and safranal. Processing of Crocus corms with EMF showed the greatest efficiency in increasing the production of secondary metabolites in saffron. EMF increased the content of marker compounds in stigmas (crocin 4: from 8.95 to 431.17 mg/g; crocin 3: from 6.27 to 164.86 mg/g; picrocrocin: from 0.4 to 1.0 mg/g), although the observed effects on growth were neutral or slightly positive. The obtained findings indicate that treatment of C. sativus corms with EMF has the potential application for increasing the quality of saffron by enhancing the amounts of biologically active compounds.

On Seedling Morphoanatomy of Asteraceae Campestral Species: Some Adaptative and Taxonomic Considerations

Theoretical Framework: The vegetation of Parana State fields is composed mainly of woody grassy savanna, and one of the largest families in specific richness is Asteraceae. The campestral Asteraceae occurs in three microhabitats as dry fields (steppes “stricto sensu”), rocky outcrops (rupestrian vegetation refuges) and humid fields (higrophyllous steppes). Morphology and structure of Asteraceae seedlings can be useful for species recognition in the field at the juvenile stage, and to understand how seedlings establish themselves in different microhabitats. Objective: The aim of this paper was to analyze the seedling structure of 17 Asteraceae species, and to summarize some considerations on anatomical characters of the seedlings, which may be variations environmentally induced and they have some taxonomic or evolutionary value. Method: Cipselae of 17 species of Asteraceae were collected in the state parks of Paraná, Brazil, and placed to germinate in Petri plates. The seedling development occurred in greenhouse. Root, hypocotyl, cotyledons, epicotyl and eophylls were sectioned in rotation microtome, and analyzed in light microscope. Cotyledons and eophylls were investigated in a scanning electronic microscope. Results: Roots are diarch or tetrarch. Hypocotyl may have the root structure and partially or wholly as transition root-stem structure. Epicotyl shows the stem structure. Cotyledons and eophylls are dorsiventral. Trichome density and amphistomaty are xeromorphic characters that occur in the cotyledons and eophylls of the species. Conclusion: Some structural characters have diagnostic value for separation of investigated species, such as hypocotyl structure, root/stem transition type, epidermis, mesophyll tissues and midrib saliency of the cotyledons and eophylls, and presence of secretory ducts.

Impact of leaf trichomes and stomatal density on the response of three soybean varieties to sucking pest infestation

Chemical pesticides disrupt local ecosystems, reduce populations of natural predators, and contribute to the evolution of pest resistance. Therefore, developing pest-resistant crop varieties is one of the most promising and environmentally friendly alternatives for pest control today. In the present study field experiments were conducted over two consecutive growing seasons in 2022 and 2023 to explore pest resistance among three soybean varieties viz. Crawford, Giza 111, and Giza 22. The research aimed to assess pest infestation resistance among these varieties, considering various leaf morphological factors. Four key pests were evaluated in the study viz. whiteflies (Bemisia tabaci Genn), spider mites (Tetranychus urticae Koc), aphids (Aphis gossypii Glover), and thrips (Thrips tabaci Lind)). The soybean varieties exhibited differences in susceptibility, and pest density varied across the two growing seasons. Crawford and Giza 111 demonstrated lower resistance, characterized by reduced leaf hair density and an increased number of stomata per leaflet. In contrast, Giza 22 was the most susceptible, featuring a higher density of trichomes and lower stomata density. In terms of field yield, Crawford produced the highest yield, followed by Giza 111, while Giza 22 yielded the least. The results of this study underscore the importance of selecting resistant plant varieties in future pest resistance improvement programs.

Exploring the role of FAT genes in Solanaceae species through genome-wide analysis and genome editing.

Plants produce numerous fatty acid derivatives, and some of these compounds have significant regulatory functions, such as governing effector-induced resistance, systemic resistance, and other defense pathways. This study systematically identified and characterized eight FAT genes (Acyl-acyl carrier protein thioesterases), four in the Solanum lycopersicum and four in the Solanum tuberosum genome. Phylogenetic analysis classified these genes into four distinct groups, exhibiting conserved domain structures across different plant species. Promoter analysis revealed various cis-acting elements, most of which are associated with stress responsiveness and growth and development. Micro-RNA (miRNA) analysis identified specific miRNAs, notably miRNA166, targeting different FAT genes in both species. Utilizing clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-mediated knockout, mutant lines for SlFATB1 and SlFATB3 were successfully generated and exhibited diverse mutation types. Biochemical evaluation of selected mutant lines revealed significant changes in fatty acid composition, with linoleic and linolenic acid content variations. The study also explored the impact of FAT gene knockout on tomato leaf architecture through scanning electron microscopy, providing insights into potential morphological alterations. Knocking out of FAT genes resulted in a significant reduction in both trichome and stoma density. These findings contribute to a comprehensive understanding of FAT genes in Solanaceous species, encompassing genetic, functional, and phenotypic aspects.

Integrating Antixenosis Against Helicoverpa armigera (Lepidoptera: Noctuidae) and Micronutrition in Kabuli Chickpea (Cicer arietinum L.) Genotypes

ABSTRACTThe leguminous chickpea is a good source of protein, but its yield potential is frequently constrained by biotic stresses, primarily Helicoverpa armigera, a major havoc for cultivation of the crop. To develop host plant resistance for minimizing the losses due to the pod borer, five kabuli parents with desired traits for pod borer tolerance were crossed in diallel mating design to produce 10 crosses which were analysed for traits related to pod borer and nutrition. Based on correlation studies, trichome density was found positively correlated with phenol content, but both the traits were negatively associated with number of damaged seeds. Therefore, the tolerant genotypes were identified on the basis of phenol content, trichome density, number of damaged seeds and field rating. Among parents ICC 12197 was found superior in terms of yield and borer tolerance features with an intermediate pest resistance susceptible rating in addition to higher Fe content. However, significant sca effects for higher phenol content and seed yield in ICC 11764 × ICC 14190 were recorded with reduced number of damaged seeds in addition to higher Fe and Zn content. It was observed that the specific combination involved good and poor combiners for each trait. The same cross also showed significant standard heterosis in desirable direction for phenol content, trichome density, number of damaged seeds and seed yield. Additionally, the ratio of σ2 GCA to σ2 SCA revealed nonadditive gene action in controlling the expression of phenol content, trichome density, number of damaged seeds and Fe and Zn content. Thus, breeder may focus efforts on desirable cross utilizing selection in further segregating generations for higher phenol content, trichome density and Fe and Zn content in addition to yield‐related traits while lesser number of damaged seeds per plant to concentrate for development of pod borer resilient high yielding kabuli genotypes to combat micronutrient deficiency.

CmMYC2-CmMYBML1 module orchestrates the resistance to herbivory by synchronously regulating the trichome development and constitutive terpene biosynthesis in Chrysanthemum.

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.

Proteomic Insights into Trichome Responses to Elevated Elemental Stress in Cation Exchanger (CAX) Mutants.

Research on elemental distribution in plants is crucial for understanding nutrient uptake, environmental adaptation, and optimizing agricultural practices for sustainable food production. Plant trichomes, with their self-contained structures and easy accessibility, offer a robust model system for investigating elemental repartitioning. Transport proteins, such as the four functional cation exchangers (CAXs) in Arabidopsis, are low-affinity, high-capacity transporters primarily located on the vacuole. Mutants in these transporters have been partially characterized, with one of the phenotypes of the CAX1 mutant being altered tolerance to low-oxygen conditions. A simple visual screen demonstrated trichome density and morphology in cax1 and quadruple CAX (cax1-4: qKO) mutants remained unaltered. Here we used SXRF (Synchrotron X-Ray Fluorescence) to show that trichomes in CAX-deficient lines accumulated high levels of chlorine, potassium, calcium, and manganese. Proteomic analysis on isolated Arabidopsis trichomes. showed changes in protein abundance in response to changes in element accumulation. The CAX mutants showed an increased abundance of plasma membrane ATPase and vacuolar H-pumping proteins, and proteins associated with water movement and endocytosis, while also showing changes in proteins associated with the regulation of plasmodesmata. These findings advance our understanding of the integration of CAX transport with elemental homeostasis within trichomes and shed light on how plants modulate protein abundance under conditions of altered elemental levels.

Morphological Parameters of Sesame in Relation to Susceptibility to Major Sucking Insect Pests

Based on previous field screening data 15 genotypes were selected (based on the number of insect pests population/ plant) to study the role of morphological parameters of sesame. Trichome density, length and width were estimated under microscope with the help of software. The 15 selected genotypes of sesame were studied for finding trichome’s role in host plant resistance against major sucking pests; whitefly Bemisia tabaci), leafhopper (Orocius albicinctus) and mirid bug (Nesidiocoris tenuis) of sesame and the correlation studies revealed that the density of non-glandular trichome showed significant positive correlation with the population of Orocius albicinctus (r= 0.868), Nesidiocoris tenuis (r=0.549) and Bemisia tabaci (r= 0.824) while length and width of non-glandular trichomes and density of glandular trichomes showed non-significant (±) impact on the incidence of tested sucking insect pests.