Search Results (151)

Soil phosphorus (P) availability is an important determinant of productivity in Pinus massoniana (Masson pine) forests. The mechanistic bases governing the physiological and growth responses of Masson pine to varying soil P conditions remain insufficiently characterized. This study aims to decipher the adaptive strategies of Masson pine to different soil P levels, focusing on root morphological–architectural plasticity and the allocation dynamics of nutrient elements and photosynthetic assimilates. One-year-old potted Masson pine seedlings were exposed to four P addition treatments for one year: P0 (0 mg kg⁻¹), P1 (25 mg kg⁻¹), P2 (50 mg·kg⁻¹), and P3 (100 mg kg⁻¹). In July and December, measurements were conducted on seedling organ biomass, root morphological indices [root length (RL), root surface area (RSA), root diameter (RD), specific root length (SRL), and root length ratio (RLR) for each diameter grade], root architectural indices [number of root tips (RTs), fractal dimension (FD), root branching angle (RBA), and root topological index (TI)], as well as the content of nitrogen (N), phosphorus (P), carbon (C), and non-structural carbohydrates (NSCs) in roots, stems, and leaves. Compared with the P0 treatment, P2 and P3 significantly increased root biomass, root–shoot ratio, RL, RSA, RTs, RLR of finer roots (diameter ≤ 0.4 mm), nutrient accumulation ratio in roots, and starch (ST) content in roots, stems and leaves. Meanwhile, they decreased soluble sugar (SS) content, SS/ST ratio, C and N content, and N/P and C/P ratios in stems and leaves, as well as nutrient accumulation ratio in leaves. The P3 treatment significantly reduced RBA and increased FD and SRL. Our results indicated that Masson pine adapts to low P by developing shallower roots with a reduced branching intensity and promoting the conversion of ST to SS. P’s addition effectively alleviates growth limitations imposed by low P, stimulating root growth, branching, and gravitropism. Although a sole P addition promotes short-term growth and P uptake, it triggers a substantial consumption of N, C, and SS, leading to significant decreases in N/P and C/P ratios and exacerbating N’s limitation, which is detrimental to long-term growth. Under high-P conditions, Masson pine strategically prioritizes allocating limited N and SS to roots, facilitating the formation of thinner roots with low C costs. Full article

As emerging contaminants increasingly detected in aquatic and terrestrial ecosystems, environmental estrogens (EEs) pose significant ecological risks to marine ecosystems, particularly affecting photosynthetic microorganisms occupying fundamental roles in marine food webs. This review summarizes the current knowledge on the toxicological effects of EEs in marine microalgae through a systematic analysis of dose-dependent physiological, biochemical, and molecular responses. Experimental evidence reveals a biphasic response pattern characterized by growth promotion and photosynthetic enhancement in microalgae under low-concentration EE exposure (0.1–10 μg/L), while marked inhibition of both growth and photosynthetic activity was observed at elevated EE concentrations (>50 μg/L). Notably, sustained EE exposure induces metabolic reprogramming, manifested through reduced protein and polysaccharide biosynthesis concurrent with accelerated lipid accumulation. Cellular stress responses include significant ultrastructural alterations such as chloroplast membrane disruption, cell wall thickening, and the formation of multicellular aggregates. The study further elucidates the concentration-dependent modulation of toxin metabolism, with sublethal doses stimulating intracellular microcystin synthesis (1.5–2.3-fold increase), while acute exposure triggers toxin release through membrane permeabilization. At molecular levels, transcriptomic analyses identify the up-regulation of heat shock proteins (HSP70/90) and the differential expression of genes governing cell cycle progression (cyclin-D), apoptotic pathways (caspase-3), photosynthetic electron transport (psbA), and oxidative stress responses (SOD, CAT). These findings demonstrate that EEs exert multilevel impacts on microalgal physiology through interference with fundamental metabolic processes, potentially disrupting marine primary productivity and biogeochemical cycles. The identified response mechanisms provide critical insights for environmental risk assessment and establish a conceptual framework for investigating estrogenic pollutant effects in aquatic ecosystems. Full article

Understanding why some plant species become widespread while others remain restricted to limited ranges is a central challenge in ecology and biogeography. This study investigates how functional traits, including morphological, physiological, and nutrient-related traits, relate to the global registrability—defined as the likelihood of a species being observed and recorded—for 144 herbaceous plant species from Guangzhou, China. We combined field-measured morphological, physiological, and nutrient-related traits with occurrence data from the Global Biodiversity Information Facility (GBIF), quantified as the number of unique 10 km × 10 km grid cells per species. Our analyses reveal that resource-acquisitive traits—such as high leaf water content, chlorophyll concentration, and photosynthetic capacity—are positively associated with registrability, whereas traits linked to nutrient conservation (e.g., high leaf carbon content and leaf carbon-to-nitrogen ratios) show negative associations. Principal component analysis further indicates that multivariate trait axes characterized by acquisitive strategies are significantly and positively associated with higher registrability. These findings suggest that species with fast-growth, resource-intensive strategies are more likely to be encountered and reported, potentially due to both ecological generalism and observation bias. Full article

Nanobiotechnology applications in plant tissue culture have improved the development and physiology of explants, resulting in plants with high genetic homogeneity and phytosanitary quality. Silver nanoparticles (AgNPs) are well-known for their microbicidal properties, but their biochemical effects on plants require further exploration. In this work, green-synthesized AgNPs were evaluated in strawberry in vitro culture, photosynthetic pigment production, and acclimatization. AgNPs produced by Lysinibacillus fusiformis were characterized. Strawberry explants were grown in vitro on MS medium with 0, 100, 200, and 300 mg L⁻¹ AgNPs at 24 ± 2 °C and a photoperiod of 16:8 h light/dark. Shoot height and number, number of leaves, number of roots, and root length were evaluated, and chlorophyll (a, b, and total) was quantified. Rooted shoots were acclimatized ex vitro on substrates containing 0 and 200 mg L⁻¹ AgNPs. The results showed that low AgNPs concentrations had a positive impact on shoot multiplication, development, and rooting, but at higher concentrations, the effects decayed. However, chlorophyll production improved with increasing AgNP concentration. Shoots treated with AgNPs showed higher ex vitro survival. Our study has direct implications for the profitability and sustainability of commercial strawberry production. Full article

The physiological and biochemical responses of Citrus reticulata Blanco var. Gonggan (Gonggan) to high-temperature stress were explored in the present study, offering valuable insights into the growth of this plant in elevated temperature scenarios. Plants were exposed to daytime temperatures of 22 °C, 40 °C, and 45 °C, with corresponding nighttime temperatures of 17 °C, 35 °C, and 40 °C, respectively. Each treatment was administered for 12 h, with a daytime light intensity of 14,400 lux. Key parameters such as the chlorophyll content, peroxidase activity, malondialdehyde content, cytoplasmic membrane permeability, and photosynthetic metrics were assessed. The results showed that the content of malondialdehyde decreased with the increase in temperature, with the highest content at 22 °C. After high-temperature treatment at 40 °C and 45 °C, there was a significant difference (p < 0.05) compared with the Gonggan plants treated at 22 °C. Peroxidase activity exhibited an increasing trend as the temperature increased, and there was a significant difference (p < 0.05) between the peroxidase activity at 22 °C and 45 °C. Similar trends are displayed for high-temperature stress, stomatal conductance, transpiration rate, and intercellular CO₂, which initially decreased and then significantly increased. The net photosynthetic rate (Pn) showed a trend of first increasing and then decreasing. When plants were subjected to high-temperature stress at 40 °C, the net photosynthetic rate showed a significant increase compared to the control group at 22 °C, but in a 45 °C stress environment, the Pn showed a decreasing trend. In the experimental group, relative conductivity decreased with the increase in temperature. Meanwhile, Gonggan plants exhibited moderate heat tolerance to short-term or moderate high-temperature stress, primarily through antioxidant and repair mechanisms. However, their heat tolerance was limited under prolonged or extremely high-temperature conditions, characterized by significant membrane damage and photosynthetic inhibition. Overall, Gonggan plants demonstrate moderate heat tolerance, making them suitable for intermittent high-temperature environments rather than prolonged extreme heat conditions. These findings provide a foundation for understanding the adaptive strategies of Gonggan plants and their cultivation in high-temperature settings. Full article

A detailed characterization of evapotranspiration (ET) patterns is of paramount importance for optimizing irrigation scheduling and enhancing water-use efficiency in the North China Plain. To delve into this, a two-season study was conducted at the National Experimental Station for Precise Agriculture in Beijing. Using 12 weighing lysimeters, the study compared two summer maize varieties with contrasting canopy sizes: Jingke 968 (JK), characterized by a large canopy, and CF 1002 (CF), with a small canopy. The comprehensive analysis yielded the following significant findings: (1) The daily average ET rates exhibited consistent trends across cultivars, yet with notable disparities in magnitude. JK consistently demonstrated higher water consumption throughout the growth seasons. In the first season, at the V13–R1 stage, the peak daily ET of JK and CF reached 5.91 mm/day and 5.52 mm/day, respectively. In the second season, during the R1–R3 stage, these values were 5.21 mm/day for JK and 5.22 mm/day for CF, highlighting the nuanced differences in water use between the varieties under varying growth conditions. (2) Regardless of canopy size, the hourly ET fluctuations across different growth stages followed similar temporal patterns. However, the most striking inter-varietal differences in ET emerged during the R1–R3 reproductive stages, when both cultivars had achieved peak canopy development (leaf area index, LAI > 4.5). Notably, the ET differences between JK and CF adhered to a characteristic diurnal “increase–decrease” pattern. These differences peaked during mid-morning (09:00–11:00) and early afternoon (13:00–15:00), while minimal divergence was observed at solar noon. This pattern suggests complex interactions between canopy structure, microclimate, and plant physiological processes that govern water loss over the course of a day. (3) Analysis of the pooled data pinpointed two critical time periods that significantly contributed to the cumulative ET differences between the varieties. The first period was from 12:00–17:00 during the R1–R3 (anthesis) stage, and the second was from 08:00–16:00 during the R3–R5 (grain filling) stage. JK maintained significantly higher transpiration rates (Tr) compared to CF, especially during the morning hours (09:00–12:00). On average, the Tr of JK exceeded that of CF by 5.3% during the pre-anthesis stage and by 16.0% during the post-anthesis stage. These observed Tr differentials strongly indicate that canopy architecture plays a pivotal role in modulating stomatal regulation patterns. Maize varieties with large canopies, such as JK, demonstrated enhanced morning photosynthetic activity, which likely contributed to increased transpiration. At the same time, both varieties seemed to employ similar midday water conservation strategies, possibly as an adaptive response to environmental stress. In summary, this study has comprehensively elucidated the intricate relationship between the leaf area index and the evapotranspiration of summer maize across multiple timescales, encompassing periodic, daily, and hourly variations. The findings provide invaluable data-driven insights that can underpin the development of precise and quantitative irrigation strategies, ultimately promoting sustainable and efficient maize production in the North China Plain. Full article

Microalgae-based wastewater treatment systems are an environmentally friendly technology for reuse of polluted water produced in livestock farming. Since pollution removal depends on light availability, the performance should be evaluated under different seasonal conditions, even in reduced lab scale systems. This study evaluates the treatment of livestock digestate in an experimental High-Rate Algae Pond (HRAP) that recreates outdoor conditions. Chemical and biological pollution removal were analyzed, as well as the response of photosynthetic activity of the culture. Pollutant removal varied between seasons, while summer was characterized by higher nitrogen and phosphorus removal (81 and 69%, respectively), on the other hand, winter presented higher elimination of organic matter (91%) and pathogens. In this sense, P. aeruginosa removal was notably higher in winter (100%) than in summer (50%). Higher light penetration and increased photosynthetic efficiency in winter, along with greater fluctuations in pH and dissolved oxygen concentrations, contributed to higher levels of pathogen decay. Photosynthetic response tests indicated higher oxygen production per unit biomass in winter, suggesting physiological adaptations to lesser light conditions. This adaptation was correlated with the relative high pH and dissolved oxygen values registered. The findings highlight the adaptation and robustness of algae cultures as a solution for wastewater treatment and reuse in the primary sector. Full article

Oil palm (Elaeis guineensis Jacq.) is the leading global oil-producing crop due to its high oil yield. Increasing global demands for palm oil require efficient propagation. Conventional breeding is practical but slow, making micropropagation an attractive alternative for rapidly multiplying superior genotypes. However, transitioning from in vitro to ex vitro conditions causes physiological stress, restricting survival and productivity. This study assessed gas exchange and chlorophyll fluorescence dynamics during acclimatization from in vitro conditions to field establishment, comparing the seedlings obtained in vitro with conventional seed-derived palm seedlings to conventional seed-derived palms. A pronounced photosynthetic efficiency decline occurred after transfer from in vitro culture, followed by a gradual recovery. The photosynthetic rate (A) increased from 0.86 µmol m⁻² s⁻¹ early in acclimatization to 15.43 µmol m⁻² s⁻¹ in field-established seedlings. Physiological characterization using CO₂ and light response curves identified the reductions in carboxylation efficiency and overall quantum yield CO₂. These biochemical constraints gradually diminished during acclimatization, facilitating a transition from heterotrophic to autotrophic growth. Chlorophyll fluorescence analysis revealed remarkable photoinhibition during initial ex vitro stages, indicated by a decreased maximum quantum efficiency of photosystem II. However, the seedlings progressively restored photochemical function throughout subsequent acclimatization phases. These findings highlight the importance of carefully regulating environmental parameters—particularly irradiance, humidity, and carbon availability—during early seedling acclimatization. The effective management of growth conditions significantly mitigates physiological stress, ensuring robust photosynthetic activity and optimized stomatal regulation. The improved acclimatization practices, therefore, can substantially enhance seedling survival rates, physiological resilience, and the overall field performance of micropropagated oil palms. Future research should focus on refining acclimatization protocols, emphasizing targeted physiological interventions to maximize the efficiency, commercial viability, and sustainability of oil palm clonal propagation. Full article

The mechanisms underlying leaf variegation in the ornamental Ilex × ‘Solar Flare’ remain poorly understood. To investigate this phenomenon, we conducted a comprehensive characterization of its variegated leaves. Compared to green sectors, yellow sectors exhibited severe chloroplast structural abnormalities, including swollen chloroplasts, damaged thylakoid membranes, and reduced chloroplast numbers. These yellow sectors also showed significantly lower chlorophyll and carotenoid levels, along with a depletion of key chlorophyll precursors—protoporphyrin IX (Proto IX), magnesium protoporphyrin IX (Mg-Proto IX), and protochlorophyllide (Pchlide). Photosynthetic efficiency was significantly impaired. Comparative transcriptome analysis identified 3510 differentially expressed genes (DEGs) between yellow and green sectors. Key disruptions in chlorophyll biosynthesis included upregulated CHLD expression and downregulated CHLH and CHLG expression, leading to impaired chlorophyll synthesis. Additionally, chlorophyll degradation was accelerated by PAO upregulation. Defective chloroplast development in yellow sectors was associated with the downregulation of GLK1, GLK2, and thylakoid membrane-related genes (PsbC, PsbO, PsbR, PsaD, and PsaH). These molecular alterations likely drive the variegated phenotype of I. × ‘Solar Flare’. These observations advance our understanding of the genetic and physiological mechanisms regulating leaf variegation in this cultivar. Full article

Water scarcity can negatively affect crop yield, posing a significant threat to global food security, such as drought. Plant growth-promoting rhizobacteria (PGPR), either as single strains or synthetic communities (SynComs), has shown promise in alleviating drought stress in various plant species. In this study, we examined the effects of water limitation on Salvia officinalis and the potential of a SynCom composed of five phosphate-solubilizing, auxin-producing, and/or nitrogen-fixing Gram-negative bacteria to enhance plant growth and drought tolerance. Plant growth, morphology, physiology, and leaf metabolomic profiles were assessed using a combination of physiological measurements and LC-MS untargeted metabolomics. Mild water stress induced a conservative water-use strategy in S. officinalis, characterized by increased root-to-shoot ratio and altered leaf morphology, without compromising photosynthetic performance. SynCom inoculation under well-watered conditions elicited drought-like responses, including transient reductions in stomatal conductance. Leaf metabolomic analysis revealed that inoculation influenced the abundance of several metabolites, including biogenic amines and dipeptides, under both irrigation regimes. Notably, drought stress and SynCom inoculation increased histamine and α-ketoglutaric acid levels, highlighting potential impacts on food quality. Under reduced irrigation, inoculation further modulated leaf morphology and biomass allocation, promoting thicker leaves and increased root biomass allocation. These results demonstrate the ability of the SynCom to modulate plant physiology and metabolism in response to both optimal and reduced irrigation, potentially enhancing drought resilience without directly improving growth. The study also highlights the complex interactions among microbial inoculation, plant stress responses, and leaf metabolite profiles, emphasizing the importance of considering the effects on the production of bioactive compounds when developing microbial inoculants for edible plants. Full article

The homeostasis of the proline-Δ¹-pyrroline-5-carboxylate (Pro-P5C) cycle, mediated by proline dehydrogenase (ProDH), plays a critical role in plants in response to abiotic stresses. The biological function of gene CsProDH1 under drought stress and its effects on amino acid metabolism and photosynthesis through proline metabolism were investigated. Enzymatic characterization of the CsProDH1 protein was conducted in vitro. Overexpression of CsProDH1 aggravated plant stress, as evident by reduced photosynthetic efficiency and increased reactive oxygen species, which activated the Pro-P5C cycle. In contrast, silencing CsProDH1 enhanced plant drought resistance, increased proline accumulation, and protected photosynthesis. Studies indicate that exogenous amino acid application mitigates drought-induced physiological impairments in plants by maintaining cellular homeostasis, with particular efficacy observed in enhancing tea plant drought resilience through improved osmotic adjustment and antioxidant capacity. This study uncovers the significant role of CsProDH1 in plant drought resistance and its regulatory mechanism, offering potential gene targets and application strategies for enhancing crop drought resistance. Full article

The extensive utilization of nano-zero-valent iron (nZVI) and its engineered derivatives has prompted significant environmental concerns, particularly regarding their phytotoxicological impacts, which remain inadequately characterized. This investigation systematically evaluated the phytotoxicological responses induced by nZVI, Chlorella vulgaris biochar (BC), and Chlorella vulgaris biochar loaded with nano-zero-valent iron (BC/nZVI) on mung bean seed germination and subsequent seedling development. The experimental data revealed that both the nZVI and BC/nZVI treatments significantly suppressed the germination indices, including germination rate, radicle and plumule elongation, and biomass accumulation, with nZVI demonstrating the most pronounced inhibitory effects. During the vegetative growth phases, nZVI exposure substantially impaired plant morphogenesis, manifested through reduced vertical growth, diminished fresh and dry biomass production, and the onset of premature foliar chlorosis, necrosis, desiccation, and, ultimately, plant mortality. A comparative analysis indicated that the BC/nZVI composites exhibited less severe photosynthetic inhibition relative to pristine nZVI. Biochemical assays demonstrated that nZVI exposure elicited the substantial upregulation in antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), concomitant with abnormal ferric ion accumulation in root tissues. Notably, BC/nZVI composites demonstrated the partial mitigation of these physiological disturbances. These empirical findings underscore that excessive iron bioavailability from nZVI induces substantial phytotoxicological stress, while BC matrix incorporation provides the partial amelioration of these adverse effects on seedling ontogeny. Full article

Porphyra specimens are red macroalgae with significant economic importance for food and pharmaceutical industries due to their physiological activities resulting from their bioactive compounds (BACs). Due to its economic importance, this research aimed to characterize the photosynthetic and biochemical aspects of the conchocelis and blade phases of Porphyra linearis to understand and help improve production of this algae. The algae were cultured for 7 days with nutrients for blade phase measurements, while another portion was cultured without nutrients for 21 days to release carpospores, which were cultivated for 4 months. For both phases, the content of BACs (chlorophyll a, carotenoids, phycobiliproteins, phenols, carbohydrates, proteins, mycosporine-like amino acids), antioxidant activity, and photosynthetic parameters were analyzed. Most of the parameters showed the blade phase had better results than conchocelis, except for carbohydrates. Phycobiliproteins showed no statistical differences between the phases. These findings highlight that conchocelis is not a good BACs source compared to the blade phase, but it is a crucial phase in the life cycle of Porphyra. Understanding the key parameters for maintaining the cultivation of conchocelis stocks for the development of the blade phase is a way to produce macroscopic biomass of this economically important algae throughout the year. Full article

The genus Camphora encompasses species of significant ecological and economic importance, such as C. parthenoxylon and C. officinarum, which exhibit distinct phenotypic traits and stress responses. This study seeks to elucidate the molecular basis of cold tolerance through comparative transcriptomic analysis complemented by physiological characterization. RNA sequencing revealed 6123 differentially expressed genes between the two species, with enriched pathways related to cold stress, oxidative stress, carotenoid biosynthesis, and photosynthesis. Key genes, such as annexin D5, chlorophyll a/b-binding protein, early light-induced protein 1, 9-cis-epoxycarotenoid dioxygenase, were identified as critical regulators of frost resistance, photosynthetic efficiency, and carotenoid biosynthesis. Functional enrichment analyses highlighted the involvement of signal transduction, membrane stabilization, and secondary metabolism in adaptive responses. Physiological assays supported these findings, showing higher chlorophyll and carotenoid content and enhanced antioxidative enzyme activities in C. parthenoxylon. These results provide valuable insights into the genetic and biochemical mechanisms underlying stress adaptation in Camphora species and offer promising targets for enhancing resilience in economically valuable plants. Full article

Drought stress significantly impacts global agricultural productivity, necessitating the identification of resilient genotypes and genetic markers to develop stress-tolerant crops. This study evaluates 48 watermelon (Citrullus lanatus L.) genotypes under controlled drought conditions to assess their morphological, physiological, and molecular responses. Key parameters such as root length, plant height, stem diameter, SPAD index (Soil and Plant Analysis Development index), and MDA levels (Malondialdehyde) were measured. Genotypes W20, W48, W13, and W60 exhibited superior drought tolerance, characterized by enhanced biomass retention, water-use efficiency, and photosynthetic capacity. Correlation analysis revealed significant relationships among traits, such as a strong positive correlation between plant height and stem diameter (r = 0.84) and a negative correlation between MDA and root length (r = −0.99), underscoring the physiological trade-offs under stress. Molecular analyses using inter-primer binding site (iPBS) markers showed a high polymorphism rate (93.2%) and identified 18 markers significantly associated with drought-related traits. Markers iPBS-2239 and iPBS-2400 emerged as highly informative, offering the potential for marker-assisted breeding. This integrative approach highlights the complex mechanisms underlying drought tolerance in watermelons and provides valuable genetic resources and candidate genotypes for developing drought-resilient cultivars. These findings contribute to advancing breeding strategies to address the challenges of climate change and water scarcity in agriculture. Full article