Trichome Density Research Articles

Accelerated settling velocity of airborne particulate matter on hairy plant leaves

Phytoremediation has emerged as an ecofriendly technique to reduce hazardous particulate matter (PM) in the air. Although previous studies have conducted statistical analyses to reveal PM removal capabilities of various plant species according to their leaf characteristics, the underlying physical mechanism of PM adsorption of plants remains unclear. Conventional methodologies for measuring PM accumulation usually require long-term field tests and provide limited understanding on PM removal effects of individual leaf traits of various plants. In this study, we propose a novel methodology which can compare the electrostatic interactions between PMs and plant leaves according to their trichome structures by using digital in-line holographic microscopy (DIHM). Surface characteristics of Perilla frutescens and Capsicum annuum leaves are measured to examine electrostatic effects according to the morphological features of trichomes. 3D settling motions of PMs near the microstructures of trichomes of the two plant species are compared in detail. To validate the PM removal effect of the hairy microstructures, a polydimethylsiloxane (PDMS) replica model of a P. frutescens leaf is fabricated to demonstrate accelerated settling velocities of PMs near trichome-like microstructures. The size and electric charge distributions of PMs with irregular shapes are analyzed using DIHM. Numerical simulation of the PM deposition near a trichome-like structure is conducted to verify the empirical results. As a result, the settling velocities of PMs on P. frutescens leaves and a PDMS replica sample are 12.11 ± 1.88% and 34.06 ± 4.19% faster than those on C. annuum leaves and a flat PDMS sample, respectively. These findings indicate that the curved microstructures of hairy trichomes of plant leaves increase the ability to capture PMs by enhancing the electric field intensity just near trichomes. Compared with conventional methods, the proposed methodology can quantitatively evaluate the settling velocity of PMs on various plant leaves according to the morphological structure and density of trichomes within a short period of time. The present research findings would be widely utilized in the selection of suitable air-purifying plants for sustainable removal of harmful air pollutants in urban and indoor environments.

Cold Tolerance Mechanisms in Mungbean (Vigna radiata L.) Genotypes during Germination

Mungbean or greengram (Vigna radiata) is an important legume crop well known for its high protein with nitrogen-fixing abilities. However, the severe yield loss in mungbean occurs due to susceptibility to low temperatures at all stages of plant growth including germination and is a serious concern for its cultivation and productivity. To select cold-tolerant genotypes, a germination-based screening at 10 °C was performed in a total of 204 germplasms. The study showed that cold stress of the initial 8-days during seedling establishment imposed a negative impact throughout the life of mungbean genotypes, which were reflected in the vegetative and reproductive phase (plant height, days to 50% flowering and pods/plant, seeds/pod, yield/plant, and 100-seed weight). The biplot analysis showed that parameters such as germination rate index, Timson’s index, mean germination time, and coefficient of the velocity of germination are the key influential germination parameters for identifying cold tolerance in the seedling stage. Identified cold-tolerant genotype (PAU911) retained higher rootlet number, leaf area, and increased chlorophyll, carotenoid, and malondialdehyde (MDA) content at 10 °C. Based on the confocal microscopic study, it is noticed that the stomatal density, open pore percentage, and trichome density were significant differences in seedlings exposed to cold stress as compared to non-stress. On the basis of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis, it is observed that a new protein identified as TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE1 (TTL1) (UNIPROT Identifier: LOC106762419) which highly correlated with the cold stress response of in the cold-tolerant genotype. Our study identifies a noble member, TTL1, whose expression has a positive role in cold tolerance response at the protein level in V. radiata. This study will help breeding programs with regard to the sustainable growth of mungbean.

Understanding Particulate Matter Retention and Wash-Off during Rainfall in Relation to Leaf Traits of Urban Forest Tree Species

Dynamic particulate matter (PM) behavior on leaves depends on rainfall events, leaf structural and physical properties, and individual tree crowns in urban forests. To address this dependency, we compared the observed relationships between PM wash-off ability and leaf traits on inner and outer crown-positioned leaves during rainfall events. Data showed significant differences in the PM wash-off ability between inner and outer crown-positioned leaves relative to rainfall events due to leaf macro- and micro-structure and geometric properties among tree species. Our results showed that PM wash-off effects on leaf surfaces were negatively associated with trichome density and size of leaf micro-scale during rainfall events. Specifically, Quercus acutissima with dense trichomes and micro-level surface roughness with narrow grooves on leaf surfaces showed lower total PM wash-off in both inner (−38%) and outer (105%) crowns during rainfall. Thus, their rough leaves in the inner crown might newly capture and/or retain more PM than smooth leaves even under rainfall conditions. More importantly, Euonymus japonicus, with a thin film-like wax coverage without trichome, led to higher total PM wash-off in both inner (368%) and outer (629%) crowns during rainfall. Furthermore, we studied the changes in PM wash-off during rainfall events by comparing particle size fractions, revealing a very significant association with macro-scale, micro-scale, and geometric features.

Molecular signatures of elite brinjal varieties towards grouping and marker–trait association for shoot and fruit borer resistance

Aim: Molecular characterization of brinjal genotypes and exploring marker trait association with a number of antixenosis and antibiosis traits in relation to shoot and fruit borer (SFB) infestation. Methodology: Seven elite brinjal genotypes including the most sensitive and highly resistant checks against SFB were sorted out from a set of 101 germplasm stocks. These were subjected to infestation with SFB in Mylar cages. Data were recorded on antixenosis and antibiosis traits related to SFB infestation. Molecular profiling was done using five RAPD and four SSR primers and the binary marker data (presence and absence of band) were analysed for clustering pattern of genotypes and marker-trait association if any for SFB infestation in brinjal. Results: The RAPD primer OPN04 and two SSR primers smSSR03 and smSSR04 emerged as the highly informative, while OPD 16 (a RAPD primer) and smSSR01 and smSSR09 showed high Rp value. The clustering based on RAPD and SSR profiling was almost similar to the grouping based on antixenosis and antibiosis traits indicating good primer efficiency for screening against SFB infestation. A few RAPD markers revealed significant marker-trait association with a number of antixenosis and antibiosis traits, and more specifically with larval weight under SFB infestation. Besides, a 400bp molecular marker 'OPC05_8' had shown significant MTA with fruit infestation, trichome density and calyx length. Interpretation: The above trait–specific molecular markers may be considered useful for screening of parental lines against SFB tolerance, and as such may be used for marker assisted selection in brinjal breeding programs. Key words: Brinjal, Clustering pattern, Genotyping, Marker-trait association, Shoot and fruit borer infestation

Ozone exposure response on physiological and biochemical parameters vis-a-vis secondary metabolites in a traditional medicinal plant Sida cordifolia L.

Tropospheric ozone is a phytotoxic air pollutant that alters the production of bioactive compounds and key metabolites of plants. A field study was established on a medicinal plant, Sida cordifolia L. (Bala) under ambient (AO; 43.3 ppb) and elevated level of ozone (ambient+20 ppb; EO) at different developmental stages. The objective of study was to analyze the changes in physiology and biochemical parameters with secondary metabolites of S. cordifolia under EO treatment using open-top chambers. Physiological parameters such as photosynthesis, chlorophyll fluorescence, water use efficiency, stomatal conductance, and intercellular CO2 concentration demonstrated a negative response at all growth stages in EO-treated plants. Trichome density increased by 83.56%, whereas photosynthetic pigments decreased under EO exposure. Total phenolics and thiols increased at 90 days after treatment (DAT) under EO, while non-enzymatic antioxidants such as flavonoids and proline induced at all growth stages. Reactive oxygen species showed a differential response at different growth stages under EO as compared with AO treatment. Enzymatic antioxidants such as ascorbate peroxidase, catalase, peroxidase, glutathione reductase, and phenylalanine ammonia-lyase increased at all growth stages under EO. However, superoxide dismutase was induced only at 30 DAT. A significant increase was observed in the contents of lignin, tannin, saponin, and alkaloids in leaves and roots of the test plant under EO exposure. Phytosterol increased under EO at all the growth stages in roots, and at 90 DAT in leaves. Despite diverse physiological, ROS, and antioxidant responses, the results demonstrated that elevated ozone boosted the production of secondary metabolites, medicinally important compounds in Sida cordifolia. The overproduction of secondary metabolites under futuristic levels of ozone could be a useful resource for the exploitation of bioactive, medicinally important compounds from S. cordifolia.

Performance of Wild Tomato Accessions and Elucidation of Resistance against Invasive Pest Phthorimaea absoluta Damage under Tropical Conditions

Invasive tomato leaf miner, Phthorimaea absoluta causes serious damage and yield loss in tomato production in open-field and protected cultivation. Use of chemical pesticides is uneconomical and adversely affects humans and the environment. Host-plant resistance is an effective, economical and eco-friendly alternative to chemical pesticides. In this study, four wild tomato accessions from the World Vegetable Center along with one susceptible check were evaluated for their antixenosis and antibiosis effects on P. absoluta. The accessions VI037241 (Solanum galapagense) and VI037240 (S. cheesmaniae) were highly resistant, leading to 85% larval mortality under no-choice conditions. Choice assay also showed less oviposition preference and reduced pupal weight. Both VI037241 and VI037240 showed the highest resistance under field conditions. The accessions of S. habrochaites (LA1777) and S. habrochaites var. glabratum (VI030462) demonstrated moderate resistance against P. absoluta. Wild accessions recorded significantly less eggs and leaf damage in field trials compared to the susceptible genotype, S. lycopersicum (CL5915). Trichome density, type and higher production of acylsugar contributed to the insect resistance. Acylsugar production in wild accessions was less during the rainy season but significantly higher than in susceptible genotype. These findings can be useful to develop P. absoluta-resistant tomato varieties in tropics.

Classification of inheritance of trichomes in different organs in zucchini (Cucurbita pepo L.)

AbstractPlant trichomes are specialized structures that develop from epidermal cells and are widely present on the surface of the aboveground tissues in plants. Trichomes play a significant role in plant development, the biotic and abiotic adaptations, and some of them have important commercial value. Trichome micromorphology of the aboveground parts of zucchini germplasm resources was observed, and the results showed that zucchini trichomes are multicellular, and they consist of head, stem, and basal cells. Zucchini trichomes were classified into seven types: type I, II, III, and VII trichomes were nonglandular, and type IV, V, and VI trichomes were glandular. Each type had a unique structure and morphology, and type I and II trichomes were long and pointy, which could easily be observed. According to the presence of type I and II trichomes, the zucchini germplasm resources were divided into long dense trichome (LDT) groups (presence of type I and II trichomes) and sparse micro trichome (SMT) groups (absence of type I and II trichomes). The F2 population derived by crossing typical LDT 16 and typical SMT 63 was constructed, and the density of type I and type II petiole trichomes was found significantly different. Petiole trichome density exhibited quantitative characteristic inheritance and was controlled by multiple genes. A study of the structure and morphology of zucchini trichomes can deepen the understanding of multicellular trichomes and lay the foundation for the morphological development of zucchini trichomes and the identification of trichome density genes, which could have important theoretical and practical application value for the selection of new zucchini varieties in the future.

Towards greenhouse cultivation of Artemisia annua: The application of LEDs in regulating plant growth and secondary metabolism.

Artemisinin is a sesquiterpene lactone produced in glandular trichomes of Artemisia annua, and is extensively used in the treatment of malaria. Growth and secondary metabolism of A. annua are strongly regulated by environmental conditions, causing unstable supply and quality of raw materials from field grown plants. This study aimed to bring A. annua into greenhouse cultivation and to increase artemisinin production by manipulating greenhouse light environment using LEDs. A. annua plants were grown in a greenhouse compartment for five weeks in vegetative stage with either supplemental photosynthetically active radiation (PAR) (blue, green, red or white) or supplemental radiation outside PAR wavelength (far-red, UV-B or both). The colour of supplemental PAR hardly affected plant morphology and biomass, except that supplemental green decreased plant biomass by 15% (both fresh and dry mass) compared to supplemental white. Supplemental far-red increased final plant height by 23% whereas it decreased leaf area, plant fresh and dry weight by 30%, 17% and 7%, respectively, compared to the treatment without supplemental radiation. Supplemental UV-B decreased plant leaf area and dry weight (both by 7%). Interestingly, supplemental green and UV-B increased leaf glandular trichome density by 11% and 9%, respectively. However, concentrations of artemisinin, arteannuin B, dihydroartemisinic acid and artemisinic acid only exhibited marginal differences between the light treatments. There were no interactive effects of far-red and UV-B on plant biomass, morphology, trichome density and secondary metabolite concentrations. Our results illustrate the potential of applying light treatments in greenhouse production of A. annua to increase trichome density in vegetative stage. However, the trade-off between light effects on plant growth and trichome initiation needs to be considered. Moreover, the underlying mechanisms of light spectrum regulation on artemisinin biosynthesis need further clarification to enhance artemisinin yield in greenhouse production of A. annua.

Bemisia tabaci (Hemiptera: Aleyrodidae): Evaluation of Leaf Trichome Density based Resistance on Several Soybean Varieties

The whitefly Bemisia tabaci (Gennadius) is one of the important soybean pests which can reduce production up to 80 %. Soybean defense mechanism against B. tabaci is affected by the physical characteristics of the leaf surface, e.g. leaf thickness, density of trichomes, and sticky glandular trichomes. The objective of this research was to investigate B. tabaci population – trichome density relationship on ten soybean varieties. The experiment was carried out in Ngale Station, Ngawi District, East Java. The tested soybean varieties were Anjasmoro, Demas 1, Dena 1, Dering 1, Devon, Detam 3, Dewah, Gema, Grayak 1, and Wilis. The experiment was done by completely randomized design with three replications. Observation on the whitefly population was conducted weekly from 2 until 10 weeks after planting on 23 sample plants in each plot. The result showed that Devon was the variety with the highest population levels of B. tabaci, 10.89 (eggs), 14.48 (nymphs) individuals per leaf, respectively. The population of B. tabaci was affected by trichomes density. Devon was the highest density of trichomes (613.7 hairs per cm2). The density of trichomes and the number of whitefly eggs and nymphs relationship were significant (R2= 0,78 (egg) and 0.84 (nymph), n= 10, ?= 1 %, F Value= 0.00157, respectively).

Testing the costs of defense against herbivores in ecotypes of Eruca sativa (Brassicaceae)

Abstract Plants of Eruca sativa from a desert population produce less vegetative biomass, flower earlier and possess higher density of trichomes than plants from a more mesic Mediterranean habitat. When eliciting plant defense mechanisms with methyl-jasmonate (MJ), trichome formation was exclusively enhanced in plants of the Mediterranean ecotype. To test the relative costs of defenses, ecologically-important traits were monitored in non-elicited plants of the two ecotypes and when defenses were induced by MJ. Opposing the expected tradeoffs of induced defense, MJ- elicitation significantly delayed bolting and flowering in plants of the desert ecotype but not in the Mediterranean ones. Moreover, MJ did not impose costs on fitness- related traits, i.e. fruit and seed production, nor differences between plants of the two ecotypes were found. It is suggested that early flowering in plants of the desert ecotype provide a mean to escape both the abiotic stressful environment as well herbivory, while induced defense in the Mediterranean ecotype was favored in habitats of more stressful biotic interactions. The results are discussed in light of the optimal defense theory and resource availability hypothesis.

Creation of new germplasm resources, development of SSR markers, and screening of monoterpene synthases in thyme

BackgroundThyme derived essential oil and its components have numerous applications in pharmaceutical, food, and cosmetic industries, owing to their antibacterial, antifungal, and antiviral properties. To obtain thyme essential oil with different terpene composition, we developed new germplasm resources using the conventional hybridization approach.ResultsPhenotypic characteristics, including essential oil yield and composition, glandular trichome density, plant type, and fertility, of three wild Chinese and seven European thyme species were evaluated. Male-sterile and male-fertile thyme species were crossed in different combinations, and two F1 populations derived from Thymus longicaulis (Tl) × T. vulgaris ‘Fragrantissimus’ (Tvf) and T. vulgaris ‘Elsbeth’ (Tve) × T. quinquecostatus (Tq) crosses were selected, with essential oil yield and terpene content as the main breeding goals. Simultaneously, simple sequence repeat (SSR) primers were developed based on the whole-genome sequence of T. quinquecostatus to authenticate the F1 hybrids. A total of 300 primer pairs were selected, and polymerase chain reaction (PCR) was carried out on the parents of the two hybrid populations (Tl, Tvf, Tve, and Tq). Based on the chemotype of the parents and their F1 progenies, we examined the expression of genes encoding two γ-terpinene synthases, one α-terpineol synthase, and maybe one geraniol synthase in all genotypes by quantitative real-time PCR (qRT-PCR).ConclusionWe used hybridization to create new germplasm resources of thyme, developed SSR markers based on the whole-genome sequence of T. quinquecostatus, and screened the expression of monoterpene synthase genes in thyme. The results of this study provide a strong foundation for the creation of new germplasm resources, construction of the genetic linkage maps, and identification of quantitative trait loci (QTLs), and help gain insight into the mechanism of monoterpenoids biosynthesis in thyme.

Identification of Resistance Traits Against Whiteflies, Bemisia tabaci in Certified Varieties and Promising Strains in Field and Semi-Field Experiments

Al-Issa, Z., M.N. Salti, M. Nabahan and A. Khalifa. 2023. Identification of Resistance Traits Against Whiteflies, Bemisia tabaci in Certified Varieties and Promising Strains in Field and Semi-Field Experiments. Arab Journal of Plant Protection, 41(2): 173-182. https://doi.org/10.22268/AJPP-41.2.173182 Plants have developed defense systems to cope with pests’ challenge, especially insects to reduce their damage. In this study, some resistance traits in 30 cotton (Gossypium hirsutum) genotypes against cotton’s whitefly, Bemisia tabaci (Genn.) were evaluated through semifield experiments, where antixenosis of certified varieties and promising strains to the insect where studied by designing adhesive cage placed on leaves of the plant third upper, insect development from egg to adult were regularly observed and rates of development and survival, lifespan, sex ratio, and total emergence of adults were monitored. Preference test was conducted through recording numbers of different insect stages in 1cm2 area. Field experiments were carried out by planting cotton genotype for two successive seasons (2018, 2019). Insect density was evaluated by measuring whiteflies density every 15 days until the end of the growing season. During the 2020 season, trichome density in 1cm2 area was determined and their length and diameter were also determined at the 8 th node of cotton genotypes. The results showed that no significant differences among cotton genotype in relation to insect survival rate, lifespan, sex ratio, and emergence rate of adult. This study revealed that there were significant differences in trichome density in 1 cm2 of leaf area ranged between 86.33 to 160.7/cm2 . The correlation was significantly negative between egg and trichome density (R= -0.984). However, no significant correlation between length and diameter of trichome with nymph and egg density. The egg density varied from 32 to 54 egg/cm2 , whereas nymph’s density varied between 3.8 to 6.1 181 Arab J. Pl. Prot. Vol. 41, No. 2 (2023) nymphs/cm2 , and the variety Raqqa 5 had the highest density of whitefly nymphs and eggs during the two seasons. Whiteflies density peak was around mid-September and started to decline until mid-October. The results obtained suggested that there is a role for trichome density in resistance to whiteflies and there aren’t antixenosis between studied cotton’s genotypes. There is a need to investigate cotton genotypes from different cotton species such as G. arboreum, G. barbadens, G. thuberi for the presence of insect resistance traits. Incorporation of such resistance in cotton cultivars is a key for sustainable pest management. Keywords: cotton’s whiteflies, egg number, nymph number, resistance traits, preference, trichome

Polyploidisation effect on trichome density in interspecific hybrids of Pennisetum glaucum (L.) R. Br. × Pennisetum purpureum (K.) Schum

This study is aimed at testing the efficiency of colchicine on inducing polyploidy in Pennisetum glaucum (L.) R. Br. ? P. purpureum (K.) Schum (BNH) and to investigate the effect of polyploidy on trichome density. Root cuttings of 4 hybrids and two check varieties were treated with different concentrations of colchicine (0, 0.05%, 0.1% and 0.2%) for different time durations (12 and 24 hrs). The ploidy level of plants was confirmed by cytogenetic studies using conventional protocol. Colchicine concentration of 0.1% for 24 hrs was found to induce polyploidy in PBN 233. Trichome density was investigated using Scanning Electron Microscopy at 100X. During the study, it was found that the trichome density decreases with increase in ploidy level.

TrichomeYOLO: A Neural Network for Automatic Maize Trichome Counting.

Plant trichomes are epidermal structures with a wide variety of functions in plant development and stress responses. Although the functional importance of trichomes has been realized, the tedious and time-consuming manual phenotyping process greatly limits the research progress of trichome gene cloning. Currently, there are no fully automated methods for identifying maize trichomes. We introduce TrichomeYOLO, an automated trichome counting and measuring method that uses a deep convolutional neural network, to identify the density and length of maize trichomes from scanning electron microscopy images. Our network achieved 92.1% identification accuracy on scanning electron microscopy micrographs of maize leaves, which is much better performed than the other 5 currently mainstream object detection models, Faster R-CNN, YOLOv3, YOLOv5, DETR, and Cascade R-CNN. We applied TrichomeYOLO to investigate trichome variations in a natural population of maize and achieved robust trichome identification. Our method and the pretrained model are open access in Github (https://github.com/yaober/trichomecounter). We believe TrichomeYOLO will help make efficient trichome identification and help facilitate researches on maize trichomes.

Comparative macro-microscopic studies of three wild Solanum species (S. melongena L., S. incanum L. and S. virginianum L.)

Background: The traditional medicinal system comprises the usage of innumerable plant species for the treatment of various ailments. Solanum, a potent medicinal genus, finds vast description in the various traditional medicinal systems world over. The effectiveness of a herbal drug relies on the usage of correct botanical sources. In this scenario of growing importance of traditional medicines and excessive loss of habitats of various medicinal plants, the procurement of genuine herbals is a challenging issue. Many related species of Solanum distributed over the world find their usage in many medicinal preparations, but the authenticity of the herbals is not promised. The identification and standardization of crude herbal drugs can be assured by the definite morphological and anatomical characterization. Materials and Methods: Macroscopical characters of all three samples collected from Attur Chat village in Salem district were observed and recorded using Nikon Digital camera D5600 and ZEISS Discovery V8 stereo microscope. The samples were preserved in formalin acetic acid, free hand sectioning was done to reveal the anatomy, and photographs were taken using Axiolab 5 trinocular microscope fitted with Axiocam 208 camera. Results: Macro-microscopic features of three important Solanum species viz S. melongena L., S. incanum L., and S. virginianum L. were characterized by morphology and anatomy studies. The stem was terete (S. incanum), flattened (S. melongena), and cylindrical (S. virginianum) in the species. The leaves were large and elliptic in S. melongena, simple ovate in S. incanum, and ovate and brittle in S. virginianum. Anatomically in the stem of S. virginianum, glandular trichomes were observed, which were absent in the other two species. In the case of leaves, the trichome type and density were varying in the three species, and trichomes were present only in the midrib of S. melongena. Variations observed in petiole and fruits were also recorded. Conclusion: The macro-microscopic characterization carried out will be worthwhile in judging the authenticity of the plants and differentiating these species from one another.

The impact of wheat resistance and bio-rational insecticides toxicity against cherry-oat aphid, Rhopalosiphum padi L. (Hemiptera: Aphididae)

Aphids cause substantial damage to the wheat crop. In order to determine how host plant resistance and insecticides manage the Rhopalosiphum padi L. Current experiments were carried out to find the influence of host plant resistance and bio-rational insecticides against aphids in wheat (Triticum aestivum L.) crop. Field experiments were carried out for two growing years (2017/18 and 2018/19) to access the resistance of wheat against the aphids. The field resistance of wheat is highly expressed in Pirsabak-08 variety (infestation range = 1-2.5) while the most susceptible variety is Faisalabad-08 (infestation range > 10). The varietal preference experiment results revealed that 5.33 aphids were attracted towards Pirsabak-08 while Faisalabad-08 stood as the most susceptible variety as 25.0 aphids were found after 72 h. The linear correlation analysis revealed that the aphid attractiveness is negatively correlated to the trichome density. A stage-specific insect growth regulator (IGR) and natural insecticides were applied to a comparatively more resistant variety. The best results were achieved with pyriproxyfen and neem, as the population rapidly declined to 2.66 and 2.60 aphids/plant, respectively. Current findings lead to the conclusion that utilizing resistant hosts against aphids along with the use of safer insecticides can significantly reduce wheat damage.

Evaluation of maize germplasm for physio-morphological traits against fall armyworm

The fall armyworm (FAW), scientific name Spodoptera frugiperda (J.E. Smith), poses a significant challenge to farmers and agricultural systems due to its ability to adapt, reproduce rapidly, and develop resistance to pesticides. Hence, it is essential to adopt effective and feasible approaches to managing FAW. The present research aimed at identifying the physio-morphological traits in 22 diverse maize genotypes that influence resistance to FAW. Among the tested ones, moderately resistant genotypes had the highest trichome density (CML 71, CML 67, and CML 335), minimum leaf area, and leaf width (DMRE 63, CML 71, and CML 67). Moderately resistant genotypes, viz., CML 67 (0.14 mm), CML 71 (0.14 mm), CML 561 (0.14 mm), and DMRE 63 (0.14 mm), exhibited significantly higher leaf toughness. Furthermore, the lowest relative water content was recorded in moderately resistant genotypes (DMRE 63, CML 71, and CML 67). The maximum cob length was observed in the moderately resistant genotype, CML 71 (18.56 cm), followed by CML 67 (18.26 cm), which was on par. Among moderately resistant genotypes, CML 71 had the greatest cob width of 4.97 cm, followed by CML 67 (4.88 cm), CML 561 (4.66 cm), CML 335 (4.66 cm), and DMRE 63 (4.62 cm), and these were statistically comparable. Of the genotypes evaluated, the moderately resistant genotypes CML 71, CML 67, and DMRE 63 registered significantly higher yields of 135.04 g/plant, 120.65 g/plant, and 117.92 g/plant, respectively. This information on physio-morphological traits is helpful in breeding programs focusing on maize resistance to FAW.

Involvement of abscisic acid in silicon-mediated enhancement of copper stress tolerance in Artemisia annua

Heavy metal (HM) toxicity is a well-known hazard which causes deleterious impact on the growth and development of plants. The impact of abscisic acid (ABA) in presence of silicon (Si) on plant development and quality traits has largely gone unexplored. The effects of ABA and Si on the growth, yield, and quality characteristics of Artemisia annua L. plants growing under copper (Cu) stress (20 and 40 mg kg−1) were investigated in a pot experiment. During this investigation, Cu stress caused severe damage to the plants but exogenous administration of Si and ABA ameliorated the harmful effects of Cu toxicity, and the plants displayed higher biomass and improved physio-biochemical attributes. Copper accumulated in the roots and shoots and its toxicity caused oxidative stress as demonstrated by the increased 2-thiobarbituric acid reactive substance (TBARS) content. It also resulted in the increased activity of antioxidant enzymes, however, the exogenous Si and ABA supplementation decreased the buildup of reactive oxygen species (ROS) and lipid peroxidation, alleviating the oxidative damage produced by HM stress. Copper toxicity had a considerable negative impact on glandular trichome density, ultrastructure as well as artemisinin production. However, combined Si and ABA enhanced the size and density of glandular trichomes, resulting in higher artemisinin production. Taken together, our results demonstrated that exogenous ABA and Si supplementation protect A. annua plants against Cu toxicity by improving photosynthetic characteristics, enhancing antioxidant enzyme activity, protecting leaf structure and integrity, avoiding excess Cu deposition in shoot and root tissues, and helping in enhanced artemisinin biosynthesis. Our results indicate that the combined application of Si and ABA improved the overall growth of plants and may thus be used as an effective approach for the improvement of growth and yield of A. annua in Cu-contaminated soils.

Registration of Arkot 0902 cotton germplasm line

AbstractArkot 0902 (Reg. no. GP‐1130, PI 700940) is a conventional cotton (Gossypium hirsutum L.) germplasm line released by the Arkansas Agricultural Experiment Station in May 2022. Arkot 0902 was derived from a cross of ‘GA 230’ (PVP 201500309) and Arkot 0012. Over 5 yr and four test sites in Arkansas, Arkot 0902 produced 10 and 20% higher lint yields than ‘UA222’ and ‘UA48’, respectively. The high lint yield of Arkot 0902 was attributed to producing more (and smaller) seed per area than UA222 or UA48. Arkot 0902 possesses leaf and stem pubescence similar to UA48 (smooth leaf) but has higher density of marginal bract trichomes. Arkot 0902 displayed high resistance to bacterial blight and was similar to UA222 and UA48 in their response to other diseases. Arkot 0902 was more resistant to tarnished plant bug than UA48 and equal to UA222. Most fiber quality traits of Arkot 0902 approached those of UA48, a high fiber–quality cultivar.

The Leaf Color and Trichome Density Influence the Whitefly Infestation in Different Cassava Cultivars.

The whitefly species Bemisia tuberculata and Aleurotrixus aepim (Hemiptera: Aleyrodidae) are considered important cassava (Manihot esculenta) pests. Leaf color and other morphological characteristics can influence the pest's interactions with the host plants. Thus, this study aimed to identify the relationship between whitefly occurrence and trichome density and leaf color in different cassava cultivars. The study was conducted in the field during the 2014/2015 and 2016/2017 crop seasons. The whitefly occurrence was surveyed in the cultivars, IAPAR 19, IPR Upira, IPR União, IAC 576-70, IAC 14, IAC 90, Catarina Branca, Santa Helena and Baianinha. The whitefly nymph quantification was correlated with non-glandular trichome density, luminosity (L*) and chroma (a* and b*) of the cassava leaves. IAPAR 19 and IAC 14 were less infested by whitefly nymphs when contrasted with IPR União, IPR Upira and Baianinha, which were the most infested. The lowest B. tuberculata infestations were correlated with lesser trichome density, highest light reflection and highest chroma in the sprout and the plant's superior third portion leaves. Low A. aepim infestation in both crop seasons made it impossible to verify its correlation with the studied cassava plant characteristics. The cultivars IAPAR 19 and IAC 14 could contribute towards B. tuberculata management in regions with a history of whitefly infestation.