Search Results (571)

Ultraviolet B (UV-B) radiation is a key environmental factor that limits plant growth and development. High UV-B intensity is a typical environmental feature in Turpan-Hami (Tuha) Basin in Xinjiang, China. In this study, the altitude-dependent UV-B adaptation strategies of plants in Tuha Basin were analyzed. Chlorophyll (Chl) and flavonoid (Fla) play an important role in absorbing UV-B radiation, scavenging free radicals, and maintaining photosynthetic performance under UV-B stress. Principal component analysis indicated that the total chlorophyll (Chl t), Chl a, Chl b, and Fla contents and the Chl a/Chl b ratio are important indicators for evaluating plant tolerance to UV-B. Noticeably, with increased altitudes, the roles of Chl b, Chl a/Chl b, and Fla become markedly significant. The characteristics of stomata, epidermal hair, and wax layer are closely correlated with the UV-B amount that reaches leaves. Epidermal hair density and cuticle thickness in leaves decreased with increased altitudes, whereas hydrogen oxide (H₂O₂) was significantly accumulated, but superoxide anion (O₂⁻) remained unchanged. High altitude significantly increased the stomatal apparatus area, density and specific leaf area. Moreover, plants without epidermal hair had a larger stomatal apparatus area compared with plants with epidermal hair. However, the presence or absence of epidermal hair had no effect on cuticle thickness, H₂O₂ and O₂⁻ levels. The carbon (C), nitrogen (N), and hydrogen (H) contents were high in plant leaves at high altitude, but the sulfur (S) content and C/N ratio were low. Taken together, plants in Tuha Basin could cope with UV-B radiation by synergistically regulating epidermal structures and synthesis of secondary metabolites. Meanwhile, these plants could further allocate and reconstruct organic elements to optimize their resource distribution in adaptation to UV-B radiation with different altitudes. Full article

Singlet oxygen (¹O₂), a reactive oxygen species, can oxidize lipids, proteins, and DNA at high concentrations, leading to cell death. Despite its extremely short half-life (10⁻⁵ s), ¹O₂ acts as a critical signaling molecule, triggering a retrograde pathway from chloroplasts to the nucleus to regulate nuclear gene expression. In this study, rice seeds were treated with 0, 5, 20 and 80 μM Rose Bengal (RB, a photosensitizer) under moderate light for 3 days to induce ¹O₂ generation. Treatment with 20 μM RB reduced stomatal density by approximately 25% in three-leaf-stage rice seedlings, while increasing the contents of pectin, hemicellulose, and cellulose in root cell walls by 30–40%. Under drought, salinity, or shading stress, 20 μM RB treatment significantly improved rice tolerance, as evidenced by higher relative water contents (49–58%) and chlorophyll contents (60–76%) and lower malondialdehyde (37–43%) and electrolyte leakage (29–37%) compared to the control. Moreover, RT-qPCR analysis revealed that the significant up-regulation of stomatal development genes (OsTMM and OsβCA1) and cell wall biosynthesis genes (OsF8H and OsLRX2) was associated with RB-induced ¹O₂ production. Thus, under controlled environmental conditions, ¹O₂ may regulate stomatal development and cell wall remodeling to enhance rice tolerance to multiple abiotic stresses. These results provide new perspectives for the improvement of rice stress tolerance. Full article

In recent years, high temperature and drought have severely impacted the growth and development of loquat [Eriobotrya japonica (Thunb.) Lindl.] plants. Although dopamine can improve the stress resistance of plants, its role in combined stress requires further exploration. This study investigated the alleviative effect and mechanism of exogenous dopamine on loquat seedlings subjected to the combined stress of high temperature and drought. The combined stress significantly reduced root viability, photosynthetic pigment content, and net photosynthetic rate (Pn) while markedly increasing reactive oxygen species (ROS) levels, thiobarbituric acid-reactive substances (TBARS) content, and electrolyte leakage (EL). The seedlings exhibited pronounced wilting symptoms, along with markedly reduced root surface area and volume. Dopamine treatment significantly alleviated combined stress-induced damage. This mitigation was manifested through substantially enhanced root viability, photosynthetic pigment content, Pn, antioxidant enzyme activities, and osmotic adjustment substances concomitantly with marked reductions in ROS, TBARS content, and EL. Dopamine significantly reduced seedling wilting severity and improved root morphological parameters. This study demonstrates that dopamine enhances loquat seedlings’ tolerance to combined stress through coordinated mechanisms: maintaining photosynthetic pigments and improving stomatal conductance to sustain photosynthetic efficiency, enhancing antioxidant enzyme activity and ROS scavenging capacity to mitigate oxidative damage, and promoting osmotic solute accumulation for osmotic potential regulation. Full article

Chlorophyll biosynthesis is essential for photosynthesis and plant development. Disruptions in this pathway often manifest as pigment-deficient phenotypes. This study characterizes the morphological, anatomical, and physiological consequences of a chlorophyll-deficient rice mutant (yellow seedling, YS) caused by a loss-of-function mutation in the OsCHLI gene, which encodes the ATPase subunit of magnesium chelatase. Comparative analyses between YSs and wild-type green seedlings (GSs) revealed that YSs exhibited severe growth retardation, altered mesophyll structure, reduced xylem and bulliform cell areas, and higher stomatal and papillae density. These phenotypes were strongly light-dependent, indicating that OsCHLI plays a crucial role in light-mediated chloroplast development and growth. Transcriptome analysis further revealed global down-regulation of photosynthesis-, TCA cycle-, and cell wall-related genes, alongside selective up-regulation of redox-related pathways. These results suggest that chlorophyll deficiency induces systemic metabolic reprogramming, prioritizing stress responses over growth. This study highlights the multifaceted role of OsCHLI in plastid maturation, retrograde signaling, and developmental regulation, providing new insights for improving photosynthetic efficiency and stress resilience in rice. Full article

Drought stress limits seedling growth, hindering morphological development and population establishment. Artocarpus nanchuanensis, a critically endangered species endemic to the karst regions of southwest China, exhibits poor population structure and limited natural regeneration in the wild, with water deficit during the seedling stage identified as a major factor contributing to its endangered status. Elucidating the physiological and molecular mechanisms underlying drought tolerance in A. nanchuanensis seedlings is essential for improving their drought adaptability and facilitating population recovery. In this study, 72 two-year-old seedlings were divided into two groups: drought (PEG) and ethephon (PEG + Ethephon), and subjected to drought-rehydration experiments. The results showed that exogenous application of 100 mg·L⁻¹ ethephon significantly improved stomatal conductance and photosynthetic pigment content in A. nanchuanensis seedlings. Under drought stress, the PEG + Ethephon group exhibited rapid stomatal closure, maintaining water balance and higher photosynthetic pigment levels. After rehydration, the PEG + Ethephon group significantly outperformed the PEG group in terms of photosynthetic rate. Ethephon treatment reduced H₂O₂ and MDA levels, enhanced antioxidant enzyme activity (SOD, CAT, POD, GR), and increased osmotic regulator activity (soluble sugars, soluble proteins, and proline), improving ROS-scavenging capacity and reducing oxidative damage. Ethephon application significantly enhanced ethylene accumulation in seedlings, while drought stress stimulated the concentrations of key ethylene biosynthetic enzymes (SAMS, ACS, and ACO), thereby further contributing to improved drought resistance. Transcriptomic data revealed that drought stress significantly upregulated key ethylene biosynthesis genes, with expression levels increasing with stress duration and rapidly decreasing after rehydration. WGCNA analysis identified eight key drought-resistance genes, providing valuable targets for future research. This study provides the first mechanistic insight into the physiological and molecular responses of A. nanchuanensis seedlings to drought and rehydration, underscoring the central role of endogenous ethylene in drought tolerance. Ethephon treatment effectively enhanced ethylene accumulation and biosynthetic enzyme activity, thereby improving drought adaptability. These findings lay a theoretical foundation for subsequent molecular functional studies and the conservation biology of this endangered species. Full article

Drought stress poses a significant threat to tree growth, making the development of drought-resistant species essential for ecological restoration. WRKY transcription factors are critical regulators of plant drought responses; however, the role of WRKY22 in the woody species Populus ussuriensis K. remains unclear. In this study, the PuWRKY22 gene was cloned from P. ussuriensis via homologous cloning and was found to be highly expressed in leaves and responsive to abscisic acid (ABA) signaling. Subcellular localization confirmed that PuWRKY22 is a nuclear protein. Using fluorescein enzyme complementation assays, PuWRKY22 was shown to bind specifically to W-box cis-elements, indicating its function as a transcriptional regulator. Under ABA and osmotic (sorbitol) stress, the seed germination rate, root growth, and biomass of tobacco and Populus davidiana × Populus bolleana strains overexpressing PuWRKY22 were significantly increased. Additionally, these overexpressed strains exhibited a reduction in reactive oxygen species (ROS) accumulation and a decrease in membrane lipid peroxidation. Transcriptomic analyses revealed that PuWRKY22 activates expression of the ABA receptor gene Ptr.PYL4 (Potri.006G104100.v4.1), which regulates stomatal closure to minimize water loss. Consistent with this, stomatal observations and photosynthetic measurements demonstrated that PuWRKY22 enhances drought tolerance by protecting photosystem II and preserving chlorophyll content. Collectively, this study elucidates the molecular mechanism by which PuWRKY22 enhances drought resistance in woody plants through ABA signaling, providing a foundation for breeding drought-tolerant forest species. Full article

Liriope muscari is a medicinal and ornamental herbaceous plant with significant economic value, as its tuberous roots are used for medicinal purposes. However, the current production of medicinal plants is characterized by wasteful use of resources and ecological risks caused by the unreasonable application of nitrogen fertilizers. In this study, based on uniform application of phosphorus and potassium fertilizers, six nitrogen application levels were set in pot experiments (expressed as N): N0: 0 kg/ha, N1: 208.33 kg/ha, N2: 416.66 kg/ha, N3: 625 kg/ha, N4: 833.33 kg/ha, N5: 1041.66 kg/ha). The morphological characteristics, photosynthetic physiology, tuber yield and quality, and seven nitrogen fertilizer utilization indices of L. muscari were analyzed and measured. Correlation analysis and structural equation modeling (SEM) were employed to investigate the mechanism by which nitrogen influences its growth and development, photosynthetic characteristics, tuber yield and quality, and nitrogen fertilizer utilization efficiency. The results showed that (1) nitrogen significantly promoted plant height, crown width, tiller number, and chlorophyll synthesis, with the N3 treatment (625 kg/ha) reaching the peak value, and the crown width and tiller number increasing by 26.44% and 38.90% compared to N0; the total chlorophyll content and net photosynthetic rate increased by 39.67% and 77.04%, respectively, compared to N0; high nitrogen (N5) inhibited photosynthesis and increased intercellular CO₂ concentration; (2) Fresh weight of tuberous roots, polysaccharide content, and saponin C content peaked at N3 (34.67 g/plant, 39.89%, and 0.21%), respectively, representing increases of 128.69%, 28.37%, and 33.66% compared to N0; (3) Nitrogen uptake, nitrogen fertilizer utilization efficiency, agronomic utilization efficiency, and apparent utilization efficiency were optimal at N3, while high nitrogen (N4–N5) reduced nitrogen fertilizer efficiency by 40–60%; (4) SEM analysis indicated that tiller number and transpiration rate directly drive yield, while stomatal conductance regulates saponin C synthesis. Under the experimental conditions, 625 kg/ha is the optimal nitrogen application rate balancing yield, quality, and nitrogen efficiency. Excessive nitrogen application (>833 kg/ha) induces photosynthetic inhibition and “luxury absorption”, leading to source-sink imbalance and reduced accumulation of secondary metabolites. This study provides a theoretical basis and technical support for the precise management of nitrogen in Liriope-type medicinal plants. It is expected to alleviate the contradictions of “high input, low output, and heavy pollution” in traditional fertilization models. Full article

Stomatal blockers are hydrophobic polymers applied to leaves to physically block stomatal pores and restrict gas exchange, and which have potential as plant growth regulators to retard growth. Three experiments in a heated glasshouse, one sown in autumn and two sown in winter, were conducted with pot-grown rapeseed plants at the four-leaf stage to evaluate retardant potential of two bio-based polymers: di-1-p-menthene (DPM) and extracted cauliflower leaf wax. Both stomatal blockers reduced stomatal conductance and plant dry weight in the autumn-sown experiment, when solar radiation was high during leaf development and stomatal conductance of water-treated plants was relatively high. Wax was more effective than DPM at reducing plant dry weight, despite no difference in stomatal conductance. In the two winter-sown experiments, when solar radiation was lower during leaf development, stomatal conductance in water-treated plants was less than in the autumn-sown experiment. Stomatal conductance was reduced by the blockers in the winter-sown experiments, but plant dry weight was unaffected. It was concluded that stomatal blockers may have potential to act as plant growth regulators to retard growth in rapeseed, but further research is necessary to define the circumstances when a response will occur. Full article

Abiotic stresses, such as heat, cold, drought, and salt, pose severe challenges to global agriculture, with climate change exacerbating these threats and intensifying risks to crop productivity and food security. Strigolactones (SLs), a class of phytohormones, play pivotal roles in mediating plant development and enhancing stress resilience. This review highlights the multifaceted mechanisms through which SLs regulate plant responses to abiotic stresses, integrating molecular, physiological, biochemical, and morphological dimensions. Molecularly, SLs regulate the expression of stress-responsive genes, such as those encoding antioxidant enzymes and mitogen-activated protein kinase (MAPK), to enhance plant acclimation and survival under abiotic stress conditions. Moreover, genes involved in SL biosynthesis and signaling pathways are indispensable in these processes. Physiologically and biochemically, SLs improve resilience by modulating photosynthesis, stomatal closure, reactive oxygen species (ROS) metabolism, and osmotic adjustment. Morphologically, SLs modulate leaf morphology, shoot development, and root architecture, enhancing plant stress tolerance. Collectively, SLs emerge as key regulators of plant tolerance to abiotic stresses, offering promising strategies for advancing crop improvement and securing agricultural sustainability in the face of climate change. Full article

Plants are constantly exposed to various environmental challenges, such as drought, flooding, heavy metal toxicity, and pathogen attacks. To cope with these stresses, they employ several adaptive strategies. This review highlights the potential of plant-derived smoke (PDS) solution as a natural biostimulant for improving plant health and resilience, contributing to both crop productivity and ecological restoration under abiotic and biotic stress conditions. Mitigating effects of PDS solution against various stresses were observed at morphological, physiological, and molecular levels in plants. PDS solution application involves strengthening the cell membrane by minimizing electrolyte leakage, which enhances cell membrane stability and stomatal conductance. The increased reactive-oxygen species were managed by the activation of the antioxidant system including ascorbate peroxidase, superoxide dismutase, and catalase to meet oxidative damage caused by challenging conditions imposed by flooding, drought, and heavy metal stress. PDS solution along with other by-products of fire, such as charred organic matter and ash, can enrich the soil by slightly increasing its pH and improving nutrient availability. Additionally, some studies indicated that PDS solution may influence phytohormonal pathways, particularly auxins and gibberellic acids, which can contribute to root development and enhance symbiotic interactions with soil microbes, including mycorrhizal fungi. These combined effects may support overall plant growth, though the extent of PDS contribution may vary depending on species and environmental conditions. This boost in plant growth contributes to protecting the plants against pathogens, which shows the role of PDS in enduring biotic stress. Collectively, PDS solution mitigates stress tolerance in plants via multifaceted changes, including the regulation of physico-chemical responses, enhancement of the antioxidant system, modulation of heavy metal speciation, and key adjustments of photosynthesis, respiration, cell membrane transport, and the antioxidant system at genomic/proteomic levels. This review focuses on the role of PDS solution in fortifying plants against environmental stresses. It is suggested that PDS solution, which already has been determined to be a biostimulant, has potential for the revival of plant growth and soil ecosystem under abiotic and biotic stresses. Full article

Agro-photovoltaics (APV) or agrivoltaic systems integrate crop cultivation with solar energy production, offering a promising solution through the dual-use of land. This two-year study (2023 and 2024) examined the effects of an APV system on rice production. The results indicated that APV arrays created spatially variable light environments, with shadow lengths following predictable solar azimuth patterns and cloudy conditions mitigating shading effects through enhanced diffuse light. Compared with CK (non-shadow area), inter-panel plots (BP) maintained 77% photosynthetic efficiency and 85.4% plant height, whereas the areas beneath the panel showed a significant decrease in the relative chlorophyll content (SPAD values), photosynthesis rates, and yield. BP plots preserved a 78% fruiting rate through adaptive stomatal regulation, whereas LP zones (directly under the low eave) exhibited 35% higher intercellular CO₂ because of the limited assimilation in shading. Rice yield losses were correlated with shading intensity, driven by reduced panicles and grain filling. Moreover, the APV system achieved a high land equivalent ratio of 148–149% by combining 65–66% rice yield with 82.5% photovoltaics output. Based on the microenvironment created by the APV system, optimal crop types and fertilisation are essential for enhancing agricultural yields and improving land use efficiency. Full article

Forced-air cooling (FAC) is a method for rapidly reducing the temperature of horticultural products. However, its effects on the physiological properties and quality of cut flowers remain elusively unclear. This study investigated the impact of FAC with different vent hole diameters (4, 8, and 12 cm) on multiple metabolic pathways and the quality of cut rose flowers. Compared with controls with a conventional slow cooling method, FAC using 8 cm vent holes (FAC8) prolonged the vase life of cut roses by 3 days and reduced Botrytis cinerea incidence by 60%. The data revealed that FAC8 suppressed excessive transpiration in the late vase stages while it enhanced water uptake throughout the vase period. Additionally, FAC8 reduced the respiratory rate in cut roses, decreasing cumulative respiration by 15% versus controls. When detached leaves from cut roses were subjected to water loss treatment, FAC8 induced tighter stomatal closure, resulting in a 33% smaller stomatal aperture than that of controls after 2 h. Correlation analysis of measured indices demonstrated that FAC significantly contributed to the improvement of postharvest quality (p < 0.05) via the regulation of physiological properties. In conclusion, FAC enhances the postharvest quality of cut roses by maintaining stomatal regulatory ability. Full article

Investigating the physiological responses and resistance mechanisms in plants under drought stress provides critical insights for optimizing irrigation water utilization efficiency and promoting the development of irrigation science. In this study, cotton seedlings were cultivated in a light incubator. Three drought stress levels were applied: mild (M1, 50–55% field moisture), moderate (M2, 45–50%), and severe (M3, 40–45%). Transcriptome analysis was performed under mild and severe stress. The results revealed that differentially expressed genes (DEGs) related to proline degradation were down-regulated and proline content increased in cotton. Under different stress treatments, cotton exhibited a stress-intensity-dependent regulation of carbohydrate metabolism and soluble sugar content decreased and then increased. And the malondialdehyde content analysis revealed a dose-dependent relationship between stress intensity and membrane lipid peroxidation. Stress activated the antioxidant system, leading to the down-regulation of DEGs for reactive oxygen species production in the mitogen-activated protein kinase (MAPK) signaling pathway. Concurrently, superoxide dismutase activity and peroxidase content increased to mitigate oxidative damage. Meanwhile, the photosynthetic performance of cotton seedlings was inhibited. Chlorophyll content, stomatal conductance, the net photosynthetic rate, the transpiration rate and water use efficiency were significantly reduced; intercellular carbon dioxide concentration and leaf stomatal limitation value increased. But photosynthesis genes (e.g., PSBO (oxygen-evolving enhancer protein 1), RBCS (ribulose bisphosphate carboxylase small chain), and FBA2 (fructose-bisphosphate aldolase 1)) in cotton were up-regulated to coordinate the photosynthetic process. Furthermore, cotton seedlings differentially regulated key biosynthesis and signaling components of phytohormonal pathways including abscisic acid, indoleacetic acid and gibberellin. This study elucidates the significant gene expression of drought-responsive transcriptional networks and relevant physiological response in cotton seedlings and offers a theoretical basis for developing water-saving irrigation strategies. Full article

Stomata, highly specialized structures that evolved on the aerial surfaces of plants, play a crucial role in regulating hydration, mitigating the effects of abiotic stress. Stomatal lineage development involves a series of coordinated events, such as initiation, stem cell proliferation, and cell fate determination, ultimately leading to the differentiation of guard cells. While core transcriptional regulators and signaling pathways controlling stomatal cell division and fate determination have been characterized over the past twenty years, the molecular mechanisms linking stomatal development to dynamic environmental cues remain poorly understood. Therefore, stomatal development is considered an active and compelling frontier in plant biology research. On the one hand, this review aims to provide an understanding of the molecular networks governing stomatal ontogenesis, which relies on the activation and function of the transcription factors SPEECHLESS (SPCH), MUTE, and FAMA; the EPF–TMM and ERECTA receptor systems; and downstream MAPK signaling. On the other hand, it synthesizes current discoveries of how hormonal signaling pathways regulate stomatal development in response to environmental changes. As the climate crisis intensifies, the understanding of the complex interplay between stress stimuli and key factors regulating stomatal development may reveal key mechanisms that enhance plant resilience under adverse environmental conditions. Full article

Maize–soybean intercropping is widely practised to improve land use efficiency, but shading from maize often limits soybean growth and productivity. Melatonin, a plant signaling molecule with antioxidant and growth-regulating properties, has shown potential in mitigating various abiotic stresses, including low light. This study investigated the efficacy of applying foliar melatonin (MT) to enhance shade tolerance and yield performance of soybean under intercropping. Four melatonin concentrations (0, 50, 100, and 150 µM) were applied to soybean grown under mono- and intercropping systems. The results showed that intercropping significantly reduced growth, photosynthetic activity, and yield-related traits. However, the MT application, particularly at 100 µM (MT₁₀₀), effectively mitigated these declines. MT₁₀₀ improved plant height (by up to 32%), leaf area (8%), internode length (up to 41%), grain yield (32%), and biomass dry matter (30%) compared to untreated intercropped plants. It also enhanced SPAD chlorophyll values, photosynthetic rate, stomatal conductance, chlorophyll fluorescence parameters such as Photosystem II efficiency (ɸPSII), maximum PSII quantum yield (Fv/Fm), photochemical quenching (qp), electron transport rate (ETR), Rubisco activity, and soluble protein content. These findings suggest that foliar application of melatonin, especially at 100 µM, can improve shade resilience in soybean by enhancing physiological and biochemical performance, offering a practical strategy for optimizing productivity in intercropping systems. Full article