Search Results (9,964)

Acetolactate synthase (ALS) is an important enzyme in plant branched-chain amino acid biosynthesis and the target of several major herbicide classes. Despite its agronomic importance, the role of ALS genes in stress adaptation in the invasive weed Amaranthus palmeri remains unstudied. In this study, four ApALS genes with high motif conservation were identified and analyzed in A. palmeri. Phylogenetic analysis classified ApALS and other plant ALS proteins into two distinct clades, and the ApALS proteins were predicted to localize to the chloroplast. Gene expression analysis demonstrated that ApALS genes are responsive to multiple stresses, including salt, heat, osmotic stress, glufosinate ammonium, and the ALS-inhibiting herbicide imazethapyr, suggesting roles in both early and late stress responses. Herbicide response analysis using an Arabidopsis thaliana ALS mutant (AT3G48560) revealed enhanced imazethapyr resistance, associated with higher chlorophyll retention. Furthermore, high sequence homology between AT3G48560 and ApALS1 suggests a conserved role in protecting photosynthetic function during herbicide stress. This study provides the first comprehensive analysis of the ALS gene family in A. palmeri and offers important insights into its contribution to stress resilience. These findings establish a vital foundation for developing novel strategies to control this pervasive agricultural weed and present potential genetic targets for engineering herbicide tolerance in crops. Full article

Halophytes are increasingly recognized as sustainable crops that offer a wide range of nutrients. This study provides a nutritional characterization of annual (Salicornia europaea) and perennial (Sarcocornia fruticosa, Arthrocaulon macrostachyum) species of glasswort, collected from different coastal habitats in southern Italy. S. europaea was also cultivated under non-saline conditions. Results showed differences in mineral content, and bioactive compounds among genotypes, but they were modulated by environmental conditions, leading to significant site-specific variation. S. europaea, regardless of the collecting sites, exhibited the highest concentration of minerals (K, Ca, and Mg), chlorophylls, carotenoids, and phenolic compounds as well as antioxidant activity. A. macrostachyum stood out for its high flavonoid and sterol content, exhibiting other nutritional traits comparable to S. europaea when collected in a more arid site. A. macrostachyum and S. fruticosa displayed similar compositional features, showing the highest anthocyanin and iodine (187.8 µg 100 g⁻¹ FW, on average) content. Sodium and potassium—critical for hypertension management—varied, exceeding the recommended Na/K ratio (1) for human consumption, especially in A. macrostachyum grown close to the sea. The most promising result was observed in non-saline S. europaea and in an A. macrostachyum sample (1.7, on average). Overall findings confirm the potential of both annual and perennial glassworts as nutritionally rich, sustainable crops for marginal environments. Full article

Cytokinins (CKs) are central regulators of leaf senescence, yet their cultivar-specific functions in cereals remain insufficiently understood. Here, we examined dark-induced senescence (DIS) in three barley (Hordeum vulgare L.) cultivars: Carina, Lomerit, and Bursztyn, focusing on responses to exogenous benzyladenine (BA) and inhibition of endogenous CK biosynthesis via the mevalonate (MVA) pathway using lovastatin (LOV). Bursztyn, a winter cultivar, displayed a previously uncharacterized stay-green phenotype, characterized by delayed chlorophyll and protein degradation and reduced sensitivity to BA with respect to chlorophyll retention. In contrast, Carina (spring) senesced rapidly but exhibited strong responsiveness to BA. Lomerit (winter) showed an intermediate phenotype, combining moderate natural resistance to senescence with clear responsiveness to BA. CK application suppressed SAG12 cysteine protease accumulation in all cultivars, serving as a marker of senescence and N remobilization, stabilized photosystem II efficiency, preserved photosynthetic proteins, and alleviated oxidative stress without promoting excessive energy dissipation. Although BA only partially mitigated the decline in net CO₂ assimilation, it sustained ribulose-1,5-bisphosphate regeneration, supported electron transport, and stabilized Rubisco and Rubisco activase. Moreover, LOV-based inhibition of the MVA pathway of CK biosynthesis revealed that endogenous CK contributions to senescence delay were most pronounced in Lomerit, moderate in Bursztyn, and negligible in Carina, indicating genotype-specific reliance on MVA-versus methylerythritol phosphate (MEP) pathway-derived CK pools. Collectively, these findings identify Bursztyn as a novel genetic resource for stay-green traits and demonstrate that BA delays DIS primarily by maintaining photosynthetic integrity and redox balance. The results highlight distinct regulatory networks shaping CK-mediated senescence responses in cereals, with implications for improving stress resilience and yield stability. Full article

Industrial wastewater can serve as a low-cost nutritional source for sustainable microalgal biomass production. This study investigated the biomass of Chlorella vulgaris var. vulgaris TISTR 8261 grown in untreated wastewater collected from four food industry factories in Phra Nakhon Sri Ayutthaya Province, Thailand. Among them, wastewater from a processed food production plant (PFPP) supported the highest algal growth. Supplementation with 17.4 mM sodium acetate significantly improved algal biomass yield. Further optimization with 3.7 mM NH₄Cl, 1.0 mM KH₂PO₄, 0.2 mM MgSO₄, and a moderate concentration of trace minerals enhanced the specific growth rate and chlorophyll concentration. Scaled-up cultivation in 3.5 L culture bottles in optimized PFPP yielded a maximum biomass yield of 8.436 ± 0.378 g L⁻¹, comparable to 6.498 ± 0.436 g L⁻¹ in standard TAP medium. Biomass composition analysis after 15 days of cultivation revealed 42.70 ± 1.40% protein, 17.10 ± 1.60% carbohydrate, and 1.90 ± 0.10% lipid on a dry weight basis. These findings demonstrate that optimized PFPP wastewater can effectively support high-density cultivation of C. vulgaris var. vulgaris TISTR 8261, yielding nutritionally rich biomass, and offering a cost-effective and environmentally sustainable strategy for industrial-scale microalgal production. Full article

Cucumber green mottle mosaic virus (CGMMV, Tobamovirus viridimaculae) is a tobamovirus that induces leaf green mottling, mosaic patterns, bleaching, fruit sponginess, rotting, and malformation symptoms in various cucurbit crops. The underlying mechanisms by which CGMMV elicits these symptoms have yet to be elucidated. In the present study, we observed that the infection of CGMMV in bottle gourd, but not in N. benthamiana, led to the significant upregulation of a key gene involved in chlorophyll degradation, Chlorophyllase 1 (CLH1). This induction may be closely linked to chlorophyll degradation, particularly that of chlorophyll a (Clh a) in bottle gourd plants. Phylogenetic analysis showed that the amino acid sequence of BgCLH1 has a closer relationship with those of CLH1 from other cucurbit crops and has a relatively farther relationship with those of the well-studied CLH1 from Arabidopsis thaliana and Citrus sinensis. Further, confocal microscopy analysis indicated that BgCLH1 may be localized to the cytoplasm instead of the chloroplast. Moreover, silencing of the BgCLH1 gene not only reduced viral accumulation but also resulted in an increase in chlorophyll content. Similar results were also observed in watermelon, suggesting that this regulatory mechanism may be conserved across cucurbit crops. Our findings thus reveal a complex and intricate interplay between viral infection and the chlorophyll metabolic pathway. Full article

Mikania micrantha, commonly known as mile-a-minute weed, is listed among the world’s top 10 worst weeds. Although native to humid regions of South America, it has recently been found to colonize arid habitats as well. Despite pronounced seasonal hydroclimatic variations in South China and increasing drought due to global climate change, the mechanisms underlying M. micrantha’s drought tolerance remain poorly understood. In this study, we compared the photosynthetic responses of M. micrantha leaves and stems between the dry (June) and wet (December) seasons through field experiments. We measured changes in phenotype, photosynthetic characteristics, and the content of antioxidant and osmotic adjustment substances, using the co-occurring native vine Paederia scandens as a control. The results revealed that during the dry season, M. micrantha leaves exhibited wilting, along with significant reductions in relative water content (RWC), chlorophyll (Chl), soluble sugar (SS), and soluble protein (SP). In contrast, the stems of M. micrantha maintained relatively stable phenotypes and chlorophyll levels compared to those of P. scandens. Notably, M. micrantha stems exhibited significant increases in vessel wall thickness, vessel density, total phenol content, and the activities of peroxidase (POD) and ascorbate peroxidase (APX). Furthermore, compared to P. scandens, M. micrantha stems displayed a greater increase in cortex proportion, flavonoid content, and soluble protein content. Expression analysis of bZIP transcription factors further revealed drought-responsive upregulation of specific genes (bZIP60, ZIP42-1), suggesting their potential involvement in drought response. These results indicate that although the leaves of M. micrantha are susceptible to prolonged drought, the stems exhibit considerable resilience, which may be attributed to a combination of traits including structural modifications in stem anatomy, enhanced antioxidant capacity, and osmotic adjustment. These insights suggest that stem-specific adaptations are key to its drought tolerance, providing a theoretical foundation for understanding the habitat distribution of M. micrantha and informing effective management strategies. Full article

Arbuscular Mycorrhizal Fungi (AMF) can form symbiotic relationships with most plants. They can alleviate the toxic effects of heavy metals on plants. This study analyzed the effects of AMF (Diversispora versiformis, D.v.) on the physiological responses and root organic acid secretion of tomato (Solanum lycopersicum L.) under cadmium (Cd) stress, in order to elucidate how AMF enhance Cd tolerance. The results indicated that when the AMF inoculation rate of tomato seedlings ranged from 26.75% to 38.23%, the AMF treatment significantly promoted tomato growth. Cd significantly reduced the agronomic traits of tomato. However, AMF inoculation dramatically lowered the Cd level from 19.32 mg/kg to 11.54 mg/kg in tomato roots, and effectively reduced the negative effect of Cd toxicity on seedling growth. Cd stress also significantly reduced the chlorophyll fluorescence parameters, chlorophyll contents, and photosynthetic intensity parameters in seedling leaves, while the AMF treatment significantly increased these indicators. Under Cd stress, the AMF treatment significantly increased the activities of SOD, POD, and CAT, and reduced the levels of reactive oxygen species and the contents of osmotic regulatory substances in roots. Under Cd stress conditions, the AMF treatment also significantly increased the auxin level (57.24%) and reduced the abscisic acid level (18.19%), but had no significant effect on trans-zeatin riboside and gibberellin contents in roots. Cd stress markedly reduced the content of malic acid and succinic acid by 17.28% and 25.44%, respectively; however, after the AMF inoculation, these indicators only decreased by 2.47% and 2.63%, respectively. Under Cd stress, AMF could increase tomato roots’ antioxidant capacity to reduce ROS level, thereby alleviating the toxicity induced by ROS and maintaining reactive oxygen metabolism, enhancing the plant’s stress resistance. In summary, the AMF treatment enhances the osmotic regulation capacity and maintains the stability of cell membranes by reducing the levels of osmotic regulatory substances in roots. It also enhances the Cd tolerance of tomato plants by regulating the contents of root hormones and aerobic respiration metabolites, among other pathways. Therefore, inoculating plants with AMF is a prospective strategy for enhancing their adaptive capacity to Cd-polluted soils. Full article

Cultural eutrophication caused by human activity significantly impacts benthic ecosystems. This study investigated how different phytobenthic components—rhodophyte germlings, mesoalgal and macroalgal assemblages, and Ulva cf. lactuca—respond to nutrient enrichment in a tidal channel system in San Antonio Bay, Argentina. Two experiments were conducted: one in spring examined the interaction between nutrient enrichment (N + P, N + P + Fe) and grazing pressure on early and established algal communities, and the other in autumn assessed nutrient effects on assemblages and Ulva cf. lactuca. Results showed that early successional stages, such as germlings and mesoalgae, responded most strongly to nutrient inputs, while mature macroalgae remained largely unaffected. Significant growth of mesoalgae, with increased pigment concentrations (chlorophyll a, c, and carotenoids), occurred at the eutrophied SAO Channel in spring. Nutrient additions increased rhodophyte germlings but eventually reduced diatom-dominated mesoalgal growth. Mature macroalgae showed site-specific differences but did not respond to fertilization. Grazing effects were evident in treatments with protective cages, suggesting herbivory influences early-stage algal development. Overall, the study emphasizes the importance of the successional stage, grazing pressure, and environmental nutrient history in shaping benthic algal responses to eutrophication, offering key insights into the dynamics of coastal ecosystems under increasing nutrient stress. Full article

This study investigates the effects of rising temperatures on photosynthetic efficiency and stress tolerance in major Greek grapevine cultivars by using Sauvignon Blanc and Merlot as references. Muscat and Assyrtiko displayed the most heat-tolerant photosynthetic apparatus among the white cultivars, while Mavrodafni was the most heat-tolerant among the red ones, by effectively managing excess light energy. Sauvignon Blanc, although exhibiting heat susceptibility, maintained high photosystem II (PSII) functionality under heat stress by activating photoprotective mechanisms. Savvatiano and Agiorgitiko were more vulnerable to photo-oxidative stress above 35 °C, while Agiorgitiko maintained a functional photosynthetic apparatus, even at 40 °C, by shifting to a more photoprotective strategy. In contrast, Merlot, despite its resistance to photo-oxidative stress, lacked photoprotective investment, resulting in suppressed PSII under heat stress. Moschofilero was the most susceptible cultivar to photo-oxidative stress. Leaf morphological traits also contributed to heat stress tolerance, with smaller, thicker leaves facilitating thermoregulation. The present results provide important insights into specific responses to heat stress of major Greek grapevine cultivars. This knowledge may aid in selecting heat-tolerant genotypes and optimizing vineyard site selection, thereby enhancing the sustainability and climate resilience of viticulture. Full article

Lead (Pb) in soil poses serious environmental and health risks, and its removal requires complex and costly treatment methods to meet strict regulatory standards. To effectively address this challenge, innovative and efficient techniques are essential. Sepiolite-supported MnFe₂O₄ (MnFe₂O₄/SEP) composites were synthesized via a chemical co-precipitation method. The effects of MnFe₂O₄/SEP on soil pH, cation exchange capacity (CEC), available Pb content, Pb²⁺ uptake, and the activities of antioxidant enzymes in Brassica chinensis (Pak Choi) were examined. MnFe₂O₄/SEP showed superior Pb²⁺ adsorption compared to SEP alone, fitting Langmuir models, Dubinin-Radushkevich (D-R) models, Temkin models and pseudo-second-order kinetics. The maximum adsorption capacities at 298, 308, and 318 K were 459, 500 and 549 mg·g⁻¹, respectively. XPS analysis indicated that chemisorption achieved through ion exchange between Pb²⁺ and H⁺ was the main mechanism. MnFe₂O₄/SEP increased the soil pH by 0.2–1.5 units and CEC by 18–47%, while reducing available Pb by 12–83%. After treatment with MnFe₂O₄/SEP, acid-extractable and reducible Pb in the soil decreased by 14% and 39%, while oxidizable and residual Pb increased by 26% and 21%, respectively. In Brassica chinensis, MnFe₂O₄/SEP reduced Pb²⁺ uptake by 76%, increased chlorophyll content by 36%, and decreased malondialdehyde (MDA) levels by 36%. The activities of antioxidant enzymes—superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)—were decreased by 29%, 38% and 17%, respectively. These findings demonstrate that MnFe₂O₄/SEP is an efficient Pb²⁺ adsorbent that immobilizes Pb in soil mainly through ion exchange, thereby providing a highly effective strategy for remediating Pb-contaminated soils and improving plant health. Full article

The main aim of this study was to analyze the excessive biomass of invasive alien aquatic plants reducing the water quality of a lake which was restored in the past. This study was conducted on Długie Lake (26.8 ha, 17.3 m, Masurian Lake District, northeastern Poland), which was completely degraded by raw wastewater inflow. After the long-term restoration (1987–2003) and recovery of submerged macrophyte meadows, the invasion of Elodea nuttallii—an invasive alien aquatic plant (IAAP)—was observed due to the increasing water temperature in recent years, impairing the functioning, biodiversity, and ecosystem services of this urban lake, as well as causing the deterioration of lake water quality. Therefore, an excessive biomass of E. nuttallii has been removed from the lake since 2022. The analysis of physico-chemical water quality parameters showed that consecutive excessive biomass macrophyte gradual removal (three times during the growing season) helps to limit the excessive growth of E. nuttallii and also removes nutrient loads from the ecosystem. Removing excess aquatic vegetation also helps maintain the lake’s aesthetic and recreational value. Currently, the total phosphorus concentration in lake water did not exceed 0.3 mg P/L and total nitrogen did not exceed 2.0 mg N/L. Chlorophyll a contents oscillated in the range of 5 to 9 µg/L, and Secchi disk visibility exceeded 3 m. Full article

Soil salinity disrupts rhizosphere interactions, impairing root–microbe symbioses, nutrient uptake, and water relations in onion (Allium cepa L.) and garlic (Allium sativum L.). This study evaluated the efficacy of biofertilizers (Azotobacter chroococcum SARS 10 and Azospirillum lipoferum SP2) and organic amendments (sewage sludge and poultry manure) in salt-affected soils in Kafr El-Sheikh, Egypt. Five treatments were applied: (T1) control (no amendments); (T2) biofertilizer (3 L/ha for onion, 12 L/ha for garlic) + inorganic P (150 kg/ha P₂O₅ for onion, 180 kg/ha for garlic) and K (115 kg/ha K₂SO₄ for onion, 150 kg/ha for garlic); (T3) 50% inorganic N (160 kg/ha for onion, 127.5 kg/ha for garlic) + 50% organic manure (6000 kg/ha for onion, 8438 kg/ha for garlic) + P and K; (T4) biofertilizer + T3; and (T5) conventional inorganic NPK (320 kg/ha N for onion, 255 kg/ha N for garlic + P and K). Soil nutrients (N, P, K), microbial biomass carbon (MBC), dehydrogenase activity, and microbial populations were analyzed using standard protocols. Plant growth (chlorophyll, photosynthetic rate), stress indicators (malondialdehyde, proline), and yield (bulb diameter, fresh yield) were measured. Treatment T4 increased MBC by 30–40%, dehydrogenase activity by 25–35%, available N (39.7 mg/kg for onion, 35.7 mg/kg for garlic), P (17.9 mg/kg for onion), and K (108 mg/kg for garlic). Soil organic matter rose by 8–12%, and cation exchange capacity by 26–36%. Chlorophyll content improved by 25%, malondialdehyde decreased by 20–30%, and fresh yields increased by 20–30% (12.17 tons/ha for garlic). A soybean bioassay confirmed sustained fertility with 20–25% higher dry weight and 30% greater N uptake in T4 plots. These findings highlight biofertilizers and organic amendments as sustainable solutions for Allium productivity in saline rhizospheres. Full article

Polyploidization is a rapid breeding strategy for producing new varieties with superior agronomic traits. Kenaf (Hibiscus cannabinus L.), an important fiber crop, exhibits high adaptability to diverse stress conditions. However, comprehensive studies on polyploid induction, screening, and genetic identification in kenaf remain unreported. This study first established an optimal tetraploid induction system for diploid kenaf seeds using colchicine. The results showed that a 4-h treatment with 0.3% colchicine yielded the highest tetraploid induction rate of 37.59%. Compared with diploids, tetraploid plants displayed distinct phenotypic and physiological characteristics: dwarfism with shortened internodal distance, increased stem thickness, larger and thicker leaves with deeper green color and serration, as well as enlarged flowers, capsules, and seeds. Physiologically, tetraploid leaves featured increased chloroplast numbers in guard cells, reduced stomatal density, and larger pollen grains, elevated chlorophyll content. Further analyses revealed that tetraploid kenaf had elevated contents of various trace elements, enhanced photosynthetic efficiency, prolonged growth duration, and superior agronomic traits with higher biomass (54.54% higher fresh weight, 79.17% higher dry weight). These findings confirm the effectiveness of colchicine-induced polyploidization in kenaf, and the obtained tetraploid germplasm provides valuable resources for accelerating the breeding of elite kenaf varieties with improved yield and quality. Full article

Meta-cresol (m-cresol) is highly corrosive and toxic, and is widely present in industrial wastewater. As a pollutant, it adversely affects various aspects of human production and daily life. To evaluate the feasibility of using sunflowers to remediate m-cresol-contaminated wastewater, this study used Helianthus annuus L. as the test subject to analyze its tolerance and the wastewater purification efficiency under different m-cresol concentrations. The results showed that the net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), and light energy utilization efficiency (LUE) of Helianthus annuus L. exhibited an overall decreasing trend, while the intercellular CO₂ concentration (Cᵢ) initially increased and subsequently decreased with increasing m-cresol concentration. When m-cresol concentration reached or exceeded 60 mg·L⁻¹, the net photosynthetic rate and intercellular CO₂ concentration in the leaves showed opposite trends with further increases in m-cresol stress. The inhibition of net photosynthesis in sunflowers by m-cresol was mainly attributed to non-stomatal factors. The maximum photochemical efficiency (F_v/F_m), actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (q^P), PSII excitation energy partition coefficient (α), and the fraction of absorbed light energy used for photochemistry (P) all decreased with increasing m-cresol concentration. In contrast, non-photochemical quenching (NPQ), the quantum yield of regulated energy dissipation [Y(NPQ)], and the fraction of energy dissipated as heat through the antenna (D) first increased and then decreased. Under low-concentration m-cresol stress, sunflowers protected their photosynthetic system by dissipating excess light energy as heat as a stress response. However, high concentrations of m-cresol caused irreversible damage to Photosystem II (PSII) in sunflowers. Under m-cresol stress, chlorophyll a exhibited strong stability with minimal degradation. As the m-cresol concentration increased from 30 to 180 mg·L⁻¹, the removal rate decreased from 84.91% to 11.84%. In conclusion, sunflowers show good remediation potential for wastewater contaminated with low concentrations of m-cresol and can be used for treating m-cresol wastewater with concentrations ≤ 51.9 mg·L⁻¹. Full article

In the context of contemporary climate change, drought is widely recognized as a major stressor affecting plant growth. While numerous studies have demonstrated that Serendipita indica enhances stress resistance in host plants and is widely used in agriculture, research on its symbiotic interactions with woody plants for improving drought tolerance remains limited. This study investigated the effects of S. indica inoculation on the growth of Phoebe sheareri seedlings under varying drought conditions—well-watered (WW), moderate drought (MD), and severe drought (SD)—and explored the physiological mechanisms underlying improved drought resistance. The results showed that under WW conditions, S. indica inoculation promoted seedling growth and development. Under MD and SD conditions, although drought stress inhibited growth, inoculation significantly increased plant biomass, root parameters, chlorophyll content, and photosynthetic efficiency. Additionally, it alleviated drought-induced damage by reducing REC, MDA, H₂O₂, and O₂⁻ levels, while enhancing SOD, POD, and CAT activities, and increasing root ABA, GA, IAA, and CTK content. Under MD stress, adaptive changes in root architecture and hormone levels were observed, including increases in total root length, surface area, volume, average diameter, and elevated IAA and CTK levels—all of which were further enhanced by S. indica inoculation. In conclusion, symbiosis with S. indica improved drought tolerance in P. sheareri seedlings likely through enhanced photosynthesis, antioxidant enzyme activity, and hormone regulation. Full article