Search Results (213)

Plant leaf drought tolerance is regulated by the coordinated effects of water transport efficiency, transpirational water loss, and hydraulic safety. Although cotton is considered drought-tolerant, the mechanisms that coordinate water transport and gas exchange to confer drought tolerance remain incompletely understood. In this study, four soil moisture gradients were established under field conditions and maintained consistently throughout the growing season. The relationships among leaf turgor loss point (Ψ_tlp), gas exchange, and hydraulic traits were examined in two cotton cultivars at the peak flowering stage. With increasing drought treatments, Ψ_tlp, stomatal aperture ratio (g_ratio), leaf hydraulic conductance (K_leaf), leaf hydraulic conductance inside the xylem (K_x) and leaf hydraulic conductance outside the xylem (K_ox) declined significantly, with K_x showing the greatest reduction. Both K_x and g_ratio were strongly positively correlated with Ψ_tlp. Anatomically, vein density (D_v) and vessel number (Np) increased, whereas xylem vessel area (Ap) decreased. The reduction in Ap was the primary structural factor driving the decline in K_x and contributing to lower Ψ_tlp. We conclude that cotton enhances drought tolerance through a coordinated hydraulic and osmotic strategy, by modifying xylem anatomy (reducing Ap) to downregulate K_x and by adjusting osmotically to depress Ψ_tlp. The synergistic reduction in K_x and g_ratio slows the decline in leaf water potential, thereby delaying Ψ_tlp and enhancing leaf hydraulic safety during drought. This integration optimizes stomatal regulation and water transport while ensuring hydraulic safety. The findings provide a key theoretical basis and potential breeding targets for the targeted improvement of drought tolerance and water use efficiency in cotton. Full article

This study aimed to assess the phenotypic changes in tetraploids of two gooseberry genotypes (‘White Triumph’ and AGR9, 2n = 4x = 32) in relation to their diploid counterparts (2n = 2x = 16). Tetraploid plants of the ‘White Triumph’ cultivar were characterized by lower growth dynamics than the diploid (control) plants, with the exception of clone A7/2-4x, whose height was increased. Tetraploid plants from three AGR9 gooseberry clones exhibited enhanced growth dynamics compared to control plants. The stomatal length of tetraploid gooseberry genotypes was greater than that of the control, but the stomatal density was lower in tetraploids. The leaf blades and petiole lengths of the tetraploid, ‘White Triumph’, and AGR9 plants were significantly larger than those of their diploid counterparts. Almost all nine evaluated anatomical traits (upper and lower epidermis thickness, palisade and sponge tissue thickness, amount of intercellular spaces, midrib diameter, phloem and xylem thickness, and surface of midrib cells) of the leaves in tetraploids were significantly greater than those of their diploid counterparts. Principal component analysis (PCA) distinguished genotypes according to the ploidy level. The first two principal components explained 74.8% of the total variance, with PC1 (49.99%) representing the primary axis separating diploid (2x) and tetraploid (4x) genotypes. To the best of our knowledge, there have been no published reports on the phenotypic assessment of gooseberry tetraploids. The vigorous gooseberry tetraploids characterized in this study are likely the first of their kind to be reported. Full article

This study presents an integrated chemical and anatomical characterization of leaves from seven Asparagaceae species (Agave convallis Trel., A. salmiana Otto ex Salm.-Dyck, A. striata Zucc., Dasylirion acrotrichum Zucc., Nolina excelsa García-Mend. & E. Solano, Yucca filifera Chabaud, and Y. periculosa Baker). Leaf biomass was subjected to successive Soxhlet extractions to quantify extractives, followed by isolation of lignocellulosic fractions. Lignin and cellulose were analyzed by Fourier-transform infrared (FTIR) spectroscopy to determine the syringyl/guaiacyl (S/G) ratio and total crystallinity index. Leaf anatomy was examined using fluorescence microscopy. Total extractives ranged from 13.4 to 24.0%, with A. salmiana and D. acrotrichum showing the highest values. Lignin content varied markedly among genera, reaching up to 45.1% in Yucca species, whereas cellulose content ranged from 31.3 to 42.2%. Crystalline cellulose accounted for 42.1–56.9% of total cellulose, with the highest crystallinity observed in A. convallis. FTIR analysis revealed a predominance of guaiacyl-type lignin in all species except Y. periculosa (S/G = 1.2). Multivariate analyses discriminated between genera primarily based on lignin, hemicellulose, and cellulose contents. These findings highlight genus-level differences in leaf lignocellulosic composition and support the potential use of Asparagaceae leaves as feedstocks for bioenergy and biomaterial applications. Full article

Heavy metal contamination poses critical challenges for the cultivation of medicinal plants. This study explores cadmium (Cd)-induced morpho-physiological and metabolic responses in Salvia officinalis (So) and the rare endemic Salvia ceratophylloides (Sc). Plants were exposed to cadmium contamination corresponding to 5 and 10 mg kg⁻¹ Cd (100% and 200% of the Italian regulatory limit) and assessed through gas exchange, leaf anatomy, mineral profiling, polyphenol composition, antioxidant activity, and a preliminary ecotoxicological evaluation using the Artemia salina lethality bioassay. Cd predominantly accumulated in roots, reflecting a partial exclusion strategy, and caused alterations in leaf traits, water relations, and nutrient balance. While total polyphenols generally declined, species-specific responses emerged: S. ceratophylloides increased caffeic acid derivatives, whereas S. officinalis accumulated caffeic acid, lithospermic acid A, quercetin 3-O-glucuronide, and apigenin-O-pentoside at the highest Cd exposure. Polyphenol shifts were strongly associated with antioxidant capacity. Despite higher growth sensitivity, S. ceratophylloides extracts exhibited no toxicity in the A. salina assay, indicating effective metal sequestration and low bioavailability, whereas S. officinalis extracts induced moderate to high toxicity. These findings reveal contrasting Cd tolerance and detoxification strategies, highlighting the potential of integrating plant stress physiology with ecotoxicological assessment and phytostabilization approaches to safely cultivate medicinal species on contaminated soils. Full article

Fecal retention is a distinctive reproductive strategy in certain leaf beetles, which enables females to use accumulated fecal material to protect their eggs and enhance offspring survival. The adult flea beetle Asiophrida xanthospilota (Baly, 1881) is a specialist herbivore that feeds on the leaves of Cotinus coggygria Scop. (Anacardiaceae). Using light microscopy, scanning electron microscopy, and micro-computed tomography, we described and illustrated the hindgut anatomy of adult female A. xanthospilota during the pre-mated and post-mated reproductive phases. We further examined the physiological changes in the hindgut associated with fecal retention, and assessed hindgut muscle activity across these two reproductive stages. The hindgut of adult A. xanthospilota consists of three regions: ileum, colon, and rectum. The ileum is a thin, straight or coiled, tube enclosed by malpighian tubules and supported by circular and longitudinal muscles. The colon lies between the ileum and rectum, possesses a chitinized cuticle, and is externally covered with tracheae and tracheoles. A rectal valve separates the colon from the rectum, which forms the posterior end of the alimentary canal and is characterized by intimal spines and robust circular muscles. During the post-mated phase, fecal retention causes pronounced dilation of the hindgut, substantially increasing the volume occupied by food remnants. Electromyographic recordings revealed high hindgut muscle activity in pre-mated females, characterized by short and variable bursts, whereas post-mated females exhibited reduced activity with longer and more sustained bursts. The functional implications of these specialized structural features are discussed. Overall, these morphological and physiological adaptations enhance the fecal retention strategy by increasing fecal capacity, regulating hindgut motility, and enabling the formation of a protective fecal case around the egg mass. Full article

Thidiazuron, 6-benzylaminopurine riboside, and meta-topolin are cytokinins often used in apple tissue cultures. Three different CK-containing Murashige and Skoog media were used during the experiments: medium without CK or media containing 4.5 μM thidiazuron, 4.5 μM 6-benzylaminopurine riboside, or 4.5 μM meta-topolin, respectively. Comparative ultrastructural studies across cytokinin types and apple cultivars were lacking. We studied the changes in photosynthetic pigment content of the leaves with absorption spectroscopy and chloroplast structure with light and transmission electron microscopy. At the light microscopy level, large changes were detected in the length and length-to-width ratios of the chloroplasts in the spongy and palisade mesophyll cell sections in 6-benzylaminopurine riboside- and meta-topolin-treated leaves of the McIntosh scion. In the chloroplasts of the McIntosh plants treated with 6-benzylaminopurine riboside and meta-topolin, and Húsvéti rozmaring leaves treated with meta-topolin, the diameter of grana increased. In both cultivars, thidiazuron caused the height of grana to increase. Thidiazuron and 6-benzylaminopurine riboside influenced leaf anatomy both in the Húsvéti rozmaring and McIntosh cultivars. 6-benzylaminopurine riboside and thidiazuron treatments reduced the content of photosynthetic pigments in the in vitro leaves of both cultivars. In contrast, meta-topolin treatment had no significant effect on the chlorophyll content as compared to the control. Differences were observed not only among the effects of cytokinins, but even between the two apple scions examined. In in vitro apple shoot cultures, TOP maintained chloroplast integrity and pigment content, whereas TDZ exerted stress-like effects. Full article

It is generally believed that plant polyploids exhibit greater tolerance to abiotic stress conditions than their diploid counterparts. The aim of the present research was to investigate the mechanisms underlying enhanced drought tolerance in the autotetraploid apple ‘Redchief’ as compared to its diploid counterpart. The study was conducted on potted plants over two growing seasons, and simulated drought conditions were induced by limiting or withholding irrigation. Under drought stress, the responses of the clone ‘Redchief’ 4x-25 and its diploid counterpart were compared at physiological, biochemical, and molecular levels. In addition, changes in leaf anatomical structure, stomatal characteristics, and parameters related to growth dynamics were examined in drought-challenged plants. The results indicate that apple tetraploids have a greater ability to adapt to water-deficit conditions than diploids. Under drought stress, apple tetraploids exhibited better physiological and biochemical parameters and maintained a greater capacity for continued growth than diploids. We propose that the primary mechanism underlying the increased drought tolerance in apple tetraploids is a faster and more efficient activation of antioxidant defenses and proline accumulation compared to diploids. The high plasticity of anatomical traits in apple tetraploids in response to adverse environmental conditions was also demonstrated. Full article

Tolerance to metals develops independently across plant species and even among populations of the same species under strong environmental pressure. This study compares the morphology and leaf anatomy of Dianthus carthusianorum L. originating from a Zn–Pb waste dump (metallicolous ecotype, M) and from unpolluted areas (non-metallicolous ecotype, NM), exposed to toxic concentrations of Cd, Pb, or Zn under chronic (field) and acute (hydroponic) metal stress. The aim was to identify leaf anatomical adaptations that support growth of the M ecotype in metal-polluted environments and to assess structural changes induced by acute exposure in both ecotypes. In both ecotypes, metal exposure caused alterations of mesophyll cells and the formation of abundant calcium oxalate (CaOx) crystals. Two oxalate forms were determined: insoluble (CaOx crystals) and soluble oxalates, with the former predominating. Following metal treatment, the M ecotype accumulated nearly twice as much of both forms as the NM ecotype, indicating a key role of oxalates in metal detoxification via precipitation of excess metal ions as metabolically inactive CaOx. Interestingly, elevated CaOx levels were also observed in M ecotype leaves grown under control (no metal application) conditions, suggesting a genetically fixed adaptation to metal-rich environments. Full article

The response of cocoa (Theobroma cacao L.) to low oxygen availability in the soil and the possibility of recovery after stress relief are associated with the plasticity capacity of each genotype; however, studies evaluating the influence of rootstock on stress response are scarce. Thus, in the northern region of the state of Espírito Santo, municipality of São Mateus, the physiological, biochemical, and anatomical responses and recovery capacity of cocoa PS-1319 grafted onto the rootstocks TSH-1188, Cepec-2002, Pará, Esfip-02, and SJ-02 were evaluated under flooded conditions. The plants were subjected to flooding for 60 days, and their recovery capacity was assessed after this period. The gas exchange, relative chlorophyll content, stem and leaf anatomy, photosynthetic pigments, and carbohydrates were evaluated. All genotypes showed reductions in net photosynthetic assimilation, stomatal conductance, and transpiration rate in the flooded environment compared to the non-flooded environment. All pigments were degraded, with average values of Chl a, Chl b, total Chl, and total carotenoids of 9.33, 10.418, 19.75, and 590.75 μg.mL⁻¹ in the non-flooded environment and 6.43, 7.69, 14.12, and 500.33 μg.mL⁻¹ in the flooded environment. The rootstocks Cepec-2002 and Esfip-02 showed the highest carotenoid accumulation, with 585.78 and 650.47 μg.mL⁻¹, respectively, when compared to SJ-02 (474.03 μg.mL⁻¹), Pará (491.58 μg.mL⁻¹), and TSH-1188 (525.86 491.58 μg.mL⁻¹). The Pará rootstock did not show differences in stomatal density between environments, with values of 32.25 in flooding, 34.83 in non-flooding, and 31.61 in recovery. During flooding, lenticels formed in all rootstocks. After recovery, all rootstocks normalized their gas exchange, carbohydrate levels, and anatomy, showing that the root system was able to re-establish its functions, making these rootstocks suitable for areas at risk of flooding. Full article

Estimated climate change scenarios demand robust coffee cultivars tolerant to supra-optimal temperatures, water deficit, diseases, and other stresses. Wild Coffea species represent important genetic resources for resilience. The study of variations in morphological structures associated with transpiration control, such as stomata, represents an important approach for identifying genotypes with greater stress tolerance. This study evaluated stomatal density and morphology in 48 wild accessions, 24 of Coffea racemosa and 24 of C. zanguebariae, from provinces of Mozambique. Leaf samples provided microscopic images to assess stomatal traits: density (SD), polar diameter (PD), equatorial diameter (ED), stomatal functionality (SF), and leaf dry mass. Principal components were analyzed for all 48 accessions and separately by species. Mean distribution independence was tested with the Mann–Whitney test (p < 0.05). Results revealed inter- and intraspecific variation. The ability to distinguish accessions varies with the set of traits and species. A significant negative correlation between ED and SF was shared by both species, suggesting a conserved functional pattern. This study discusses the differences in stomatal traits between wild and commercial coffee species and aspects related to possible alterations of stomatal structures during their adaptation to climate change. Additionally, it points to accessions with potential use in genetic breeding programs to increase stomatal function and the possible adaptation of new cultivars. Full article

Thinopyrum intermedium (c.n. intermediate wheatgrass), marketed under the trade name Kernza, is a promising species for perennial grain production based on seed size, ease of threshing, resistance to shattering, and grain quality. Although numerous generations of breeding for seed yield have been completed, the impact of selection on non-target traits is unknown. Here, we evaluated structural and functional changes brought about by selection for seed yield over a sequence of nine selection cycles (C0 to C9). In two experiments under semi-controlled environmental conditions, we compared gas exchange (A, E, gs, and A/Ci curves), leaf and root morphology, and the structure of seedlings from 10 generations. We found that the selection for yield throughout cycles indirectly changed the leaf structure (leaf size, leaf thickness, and leaf anatomy) and physiology (carbon acquisition and transpiration per unit area), with later cycles showing larger leaves with higher rates of CO₂ assimilation and transpiration. Changes in root structure followed similar trends: selection resulted in longer, more branched, and finer roots. These changes in non-target traits are linked to resource-use strategies and to ecosystem services provided by Kernza. Understanding how the domestication of perennial grains impacts non-target traits will aid in the design of integrated breeding programs for Kernza and other perennial grain crops. Full article

Global climate change-induced precipitation reduction severely threatens the sustainability of sandy grassland ecosystems. Understanding the adaptive strategies of native psammophytes is crucial for desertification control. We integrated leaf anatomy and transcriptomics (RNA-seq/WGCNA) to decipher drought resistance in three dominant psammophytes from Horqin Sandy Grassland. The finding revealed that the C3 annual/biennial herb Artemisia scoparia exhibited the most robust transcriptomic response, with co-expression modules linking tyrosine metabolism to cuticular thickening; the C3 semi-shrub Lespedeza davurica showed superior anatomical adaptation, underpinned by phenylpropanoid biosynthesis, while the C4 perennial herb Cleistogenes squarrosa exhibited molecular signatures of high drought sensitivity, with severe drought disrupting its flavonoid biosynthesis and circadian rhythms. In this study, the C4 herbaceous species showed stronger precipitation dependence than the C3 herbs. Our study provides molecular–anatomical insights into the ecological restoration of sandy grasslands under global change, suggesting the use of shrubs as primary stabilizers for sand fixation, alongside breeding herbaceous genotypes with optimized anatomical and transcriptomic traits to meet the needs of sustainable vegetation recovery in sandy grasslands under climate change. Full article

Warm-season grasses are the main source of feed in tropical and subtropical beef cattle production systems. The objective was to assess cattle preference among three warm-season grasses and explore its relationship with forage yield and plant structural traits. The three species were cultivated in 2 × 2 m plots using a completely randomized design. Cattle preference was evaluated in spring (December 2016 and 2017), summer (March 2017), and autumn (May 2017) using six Braford steers that grazed the plots for 4 h on two consecutive days. Pre-grazing forage yield, plant height, leaf-blade length, leaf-blade width, and the proportions of five leaf tissues at three leaf regions were measured at each date. Cattle preference was variable among the three species and evaluation dates. Paspalum atratum exhibited the highest pre-grazing forage yield, and constituted the tallest plants with the longest leaves during the summer. Urochloa brizantha showed the greatest proportion of vascular bundle sheath (17–30% at the midrib region, 25–31% at the interveinal region and 14–23% at the margin region) and P. atratum exhibited the greatest number of primary vascular bundle. Cattle preference was negatively correlated with the number of primary vascular bundle, pre-grazing forage yield, plant height and leaf-blade length. Full article

Cold stress significantly impairs plant growth and development, making the study of cold resistance mechanisms a critical research focus. Oreorchis patens (Lindl.) exhibits strong cold hardiness, yet its molecular and physiological adaptations to cold stress remain unclear. This study utilized microscopy, physiological assays, and RNA sequencing to comprehensively investigate O. patens’s responses to cold stress. The results reveal that cold stress altered leaf anatomy, leading to irregular mesophyll cells, deformed chloroplasts, and variable epidermal thickness. Physiologically, SOD and POD activities peaked at 5 °C/−10 °C, while CAT activity declined; osmotic regulators (soluble sugars, proline) increased with decreasing temperatures. Compared to the reference plants (e.g., Erigeron canadensis, Allium fistulosum), O. patens exhibited lower SOD and POD but markedly higher CAT activities, alongside reduced MDA, soluble sugars, proline, and proteins, underscoring its distinctive tolerance strategy. Low temperature stress (≤10 °C/5 °C) significantly decreased the SPAD index; the net photosynthetic rate (Pn) initially increased and then approached zero within the temperature range from 30 °C/25 °C to 25 °C/20 °C; transpiration rate (Tr) and stomatal conductance (Gs) changed synchronously, accompanied by an increase in intercellular CO₂ concentration (Ci). RNA sequencing identified 1139 cold-responsive differentially expressed genes, which were primarily enriched in flavonoid/lignin biosynthesis, jasmonic acid synthesis, and ROS scavenging pathways. qRT-PCR analysis revealed the role of secondary metabolites in O. patens response to cold stress. This study was the first to discuss the physiological, biochemical, and molecular regulatory mechanisms of O. patens resistance to cold stress, which provides foundational insights into its overwintering mechanisms and informs breeding strategies for cold-hardy horticultural crops in northern China. Full article

The present study investigates the leaf anatomical traits of representatives of Gentiana section Ciminalis in the Balkan Peninsula, focusing on the ecologically and geographically vicariant species Gentiana acaulis, G. clusii, and G. dinarica. These species are distributed across a variety of mountainous habitats, including calcareous and siliceous rocky grounds, and exhibit pronounced morphological similarities that have led to misidentifications in the past. In order to address the challenges in species delimitation, a comparative analysis of leaf anatomical traits was performed on cross-sections of ten rosette leaves from each population. Statistical data analyses were conducted on 18 morphometric traits. A range of statistical techniques were used to assess variability and identify important discriminating traits, including descriptive statistics, principal component analysis, and discriminant analysis. The results indicate that the species can be distinguished based on leaf anatomy, particularly mesophyll thickness and number of cells that contain calcium oxalate crystals. The leaf of G. acaulis has a smaller mesophyll thickness (mean value: 164.31 μm), G. dinarica a larger mesophyll thickness (mean value: 365.85 μm), while G. clusii lies between these two (mean value: 305.35 μm). Crystal-containing cells are most abundant in G. clusii, where they are distributed throughout the entire leaf mesophyll; followed by G. dinarica, where the distribution of these cells are mainly in the upper half of the leaf; while they are sparse or absent in G. acaulis. These results suggest that leaf anatomy is a valuable diagnostic tool for distinguishing taxa within the section Ciminalis of the genus Gentiana. Full article