Search Results (144)

Proteomic profiling using ultrafast chromatography–mass spectrometry provides valuable insights into plant responses to abiotic factors by linking molecular changes with physiological outcomes. Nanopriming, a novel approach involving the treatment of seeds with nanoparticles, has demonstrated potential for enhancing plant metabolism and productivity. However, the molecular mechanisms underlying nanoparticle-induced effects remain poorly understood. In this study, we investigated the impact of gold nanoparticle (Au-NP) seed priming on the proteome of wheat (Triticum aestivum L.) seedlings. Differentially regulated proteins (DRPs) were identified, revealing a pronounced reorganization of the photosynthetic apparatus (PSA). Both the light-dependent reactions and the Calvin cycle were affected, with significant upregulation of chloroplast-associated protein complexes, including PsbC (CP43), chlorophyll a/b-binding proteins, Photosystem I subunits (PsaA and PsaB), and the γ-subunit of ATP synthase. The large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) exhibited over a threefold increase in expression in Au-NP-treated seedlings. The proteomic changes in the large subunit RuBisCo L were corroborated by transcriptomic data. Importantly, the proteomic changes were supported by physiological and biochemical analyses, ultrastructural modifications in chloroplasts, and increased photosynthetic activity. Our findings suggest that Au-NP nanopriming triggers coordinated molecular responses, enhancing the functional activity of the PSA. Identified DRPs may serve as potential biomarkers for further elucidation of nanopriming mechanisms and for the development of precision strategies to improve crop productivity. 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

Salt stress severely impairs photosynthesis and development in tomato seedlings. This study investigated the regulatory role of exogenous melatonin (MT) on photosynthetic performance under salt stress by determining chlorophyll content, chlorophyll a fluorescence parameters, Calvin cycle enzyme activities, and related gene expression. Results showed that salt stress significantly reduced chlorophyll content and impaired photosystem II (PSII) functionality, as evidenced by the increased minimum fluorescence (F_o) and decreased maximum quantum efficiency of PSII (F_v/F_m) and effective PSII quantum yield (Φ_PSII). MT application mitigated these negative effects, as reflected by higher F_v/F_m, increased chlorophyll content, and lower non-photochemical quenching (NPQ). In addition, MT-treated plants exhibited improved PSII electron transport and more efficient use of absorbed light energy, as shown by elevated Φ_PSII and qP values. These changes suggest improved PSII functional stability and reduced excess thermal energy dissipation. Furthermore, MT significantly enhanced both the activity and expression of key enzymes involved in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Rubisco activase (RCA), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose-1,6-bisphosphatase (FBPase), fructose-bisphosphate aldolase (FBA), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase), thereby promoting carbon fixation and ribulose-1,5-bisphosphate (RuBP) regeneration under salt stress. Conversely, inhibition of endogenous MT synthesis by p-CPA exacerbated salt stress damage, further confirming MT’s crucial role in salt tolerance. These findings demonstrate that exogenous MT enhances salt tolerance in tomato seedlings by simultaneously improving photosynthetic electron transport efficiency and upregulating the activity and gene expression of key Calvin cycle enzymes, thereby promoting the coordination between light reactions and carbon fixation processes. This study provides valuable insights into the comprehensive regulatory role of MT in maintaining photosynthetic performance under saline conditions. Full article

Despite being one of China’s largest soybean (Glycine max L. Merr.) production areas, the Huanghuaihai Farming Region (HFR) has long been plagued by suboptimal yields. While cultivar development has contributed to yield gains in the past, whether such breeding will afford resilience under more adverse climatic conditions expected in future remains an open question. Here, we conducted two-year field experiments to contrast the growth and development of soybean cultivars released between 1960 and 2010 in the HFR. We found that cultivar breeding significantly influenced phenology, with contemporary cultivars having shorter and longer vegetative and reproductive growth phases, respectively. Grain filling duration of modern cultivars (LD11, HD14, JD21, and QH34) was 10 days longer than that of older cultivars (JX23 and WF7). Maturity height of modern cultivars decreased over time to a current value of ~80 cm, despite having higher leaf area index (LAI) and SPAD values compared with older cultivars during reproductive development. The quantum yield of electron transport in photosystem I, quantum yield of electron transport chain, photosynthetic performance index, stomatal conductance, net photosynthetic rate, and Rubisco activity of contemporary cultivars was stronger than those of older cultivars during grain filling. Prolonged grain filling duration, higher LAI, greater light interception, and stronger photosynthetic capacity evoked greater rates of grain filling, leading to higher grain weight, seed number, and yield. Genetic evolution of the cultivars over time, warmer conditions, and more precipitation together afforded longer reproductive stages. Our results indicate that yield gains have been realized primarily by cultivar breeding, and to a lesser extent, beneficial climate change. We highlight dynamic source/sink relationships underpinning the co-evolution of photosynthetic traits through soybean breeding, and provide practical advice to guide future breeding efforts. Full article

Understanding the contributions of source–sink relationships to photosynthesis will help achieve high wheat grain yields. A single-factor field experiment was conducted to quantify the regulatory effects of different sink–source ratios on wheat photosynthetic characteristics, including two wheat cultivars with different source–sink relationships as materials for detailed source–sink manipulations through flag leaf removal (LR) and removal of spikelets on one side of each spike (SR). Compared with a control (CK), LR increased the sink–source ratio (23.84%) and significantly reduced the yield (16.17%), 1000-kernel weight (11.73%), and kernels per spike (7.33%). LR increased the leaves’ net photosynthetic rate (Pn) (4.27–15.82%), the electron transfer rate (3.97–14.93%), and the Rubisco activity (2.16–12.25%) in the short term, and LR increased sucrose synthesis-related enzyme activities (3.96–19.95%) and gene expressions (SPS1, SUS1, CIN1, and SUT1). Compared with CK, SR reduced the sink–source ratio (44.12%) and significantly increased the 1000-kernel weight (10.02%) but reduced the yield (43.93%) and kernels per spike (49.31%). SR reduced the leaves’ Pn (8.54–21.41%), the electron transfer rate (3.51–16.71%), and the Rubisco activity (5.96–21.51%), and the photosynthetic process was limited. SR decreased sucrose synthesis-related enzyme activities (5.12–29.09%) and gene expressions (SPS1, SUS1, CIN1, and SUT1). Therefore, a higher sink–source ratio is an important indicator of high photosynthetic efficiency, which can be used as a screening and judgment index in variety selection and cultivation regulation. Full article

Sub-optimal light environments in controlled agricultural settings often limit the productivity of plants. While LED supplementary lighting has been widely adopted to mitigate light deficiencies, the spatial arrangement of LED light sources remains a critical but under-explored factor affecting plant physiological responses. In this study, we used the affiliation function method to comprehensively analyze the effects of four spatial LED supplementary lighting configurations—top-down lighting (T1), mid-canopy upward lighting (T2), mid-canopy downward lighting (T3), and bottom-up lighting (T4)—on the growth and photosynthetic performance of tomato plants. Our findings reveal that the T1 treatment significantly increased light absorption in the upper and middle leaves, enhanced photosynthetic efficiency, promoted the CO₂ assimilation rate, and elevated the activities of key Calvin cycle enzymes, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), fructose-1,6-bisphosphatase (FBPase), transketolase (TK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and fructose-1,6-bisphosphate aldolase (FBA). These changes led to improved carbohydrate metabolism and biomass accumulation. Additionally, the T4 treatment markedly enhanced photosynthetic activity in the lower leaves, increasing sugar metabolism-related enzyme activities, such as sucrose synthase (SS), sucrose phosphate synthase (SPS), acid invertase (AI), and neutral invertase (NI). Consequently, compared with the CK treatment, the T4 treatment significantly increased the accumulation of glucose, fructose, and sucrose, with increases of 47.36%, 27.61%, and 87.21%, respectively. Furthermore, LED supplementation regulated endogenous hormone levels, thereby promoting overall plant growth. This study highlights the importance of the spatial arrangement of LEDs in optimizing light distribution and enhancing plant productivity, providing valuable theoretical and practical insights for improving agricultural practices in controlled environments. Full article

Moss walls are acknowledged, though not widely, for their urban environmental benefits: humidity control, noise reduction, and air filtration. In this pioneering study, three outdoor living moss walls were installed in separate urban green spaces in Plovdiv, Bulgaria. One and five months later, the primary moss species used, Hypnum cupressiforme, a well-established biomonitor, was analyzed for 12 potentially toxic elements. The content of all measured elements increased, with zinc (Zn) and cadmium (Cd) showing the most significant rises—17-fold and 3-fold, respectively. The element accumulation is believed to originate from industrial activities related to non-ferrous metals. In addition to accumulating toxic elements, the moss exhibited physiological responses to environmental stress. Total lipids and tocopherols, lipophilic antioxidants produced exclusively by photosynthetic organisms, showed adaptive changes. As a molecular biomarker, the expression of the rbcL gene, which encodes the largest subunit of Rubisco, was analyzed, and showed a correlation with the Ecological Risk Index derived from the moss wall data. While living moss walls have been used to some extent to enhance urban aesthetics and improve air quality, this study is the first to highlight their potential as tools for air quality monitoring. Full article

Solar radiation is crucial for intercropping, while partial shading can protect intercropped soybean leaves from irradiation damage during the pod-ripening period under high solar radiation. This study explored the leaf dynamics and soybean quality for the maize–soybean system, for monoculture soybean (MS), monoculture maize (MM), two-row maize + three-row soybean (IS2-3), and four-row maize + four-row soybean (IS4-4). The results revealed that soybean leaves under IS2-3 and IS4-4 treatments showed increases in Rubisco activity of 59.8% and 12.4% compared with MS, respectively. The antioxidant capacity in soybean leaves in MS was higher than that under intercropping treatments. Soybean leaves under IS2-3 and IS4-4 exhibited higher alpha and beta diversities in their endophytes compared with MS. The relative abundance of pathotrophs under IS2-3 was reduced by 19.1% and 22.6% compared to that of those under MS and IS4-4, respectively. The total land equivalent ratio (LER) under IS2-3 was more than 1.00, and increased by 6.4% and 15.7% compared with IS4-4 in 2023 and 2024, respectively. Soybean seeds under IS2-3 and IS4-4 showed 4.1% and 4.2% increases in crude protein content compared to those of MS, respectively. Among various biosynthesis and metabolism processes, flavone and flavonol biosynthesis exerted a stronger influence on soybean seeds in MS, IS2-3, and IS4-4. Soybean seeds under IS2-3 showed elevated genistein content and reduced daidzein content compared with those of MS. Intercropping soybean treatments, especially IS2-3, maintained leaf health during the pod-ripening period and enhanced the crude protein content compared with sole soybean treatment, thus guiding the design of intercropping in areas with high solar radiation. Full article

Phosphorus (P) is essential for crop growth, but its complex behavior in tropical soils necessitates alternative management strategies, such as foliar supplementation. Foliar-applied nutrients act as biostimulants, enhancing stress tolerance and plant productivity. This study assessed the physiological responses of soybean to foliar application of soluble monoammonium phosphate (MAP; at a rate of 5 kg ha⁻¹ each application) at different phenological stages (two during vegetative stages V₄ and V₆ and two during reproductive stages R₁ and R₃ or all four stages) across two growing seasons in tropical field conditions. Key parameters analyzed included leaf nutrient content, photosynthetic pigments, Rubisco activity, carbohydrate content, gas exchange (photosynthetic rate, stomatal conductance, transpiration, water use efficiency, and carboxylation efficiency), oxidative stress markers, and productivity indicators (100-grain weight and grain yield). MAP application improved all parameters, particularly at R₁ and R₃. Total chlorophyll increased by 29.2% at R₁ and 30.0% when applied at all four stages, while the net photosynthetic rate rose by 15.8% and 18.4%, respectively. Water use efficiency improved by 20.0% at R₁ and all four stages, while oxidative stress indicators, such as H₂O₂ levels, decreased. Rubisco activity increased most at R₃ (46.0%) and all four stages (59.9%). Grain yield was highest with MAP spread at all four stages (12.3% increase), though a single application at R₁ still boosted yield by 7.4%, compared to the control treatment. Full article

Substantial variation in the temperature dependence of parameters of the Farquhar, von Caemmerer, and Berry C₃ photosynthesis model, as well as those of in vitro Rubisco kinetic characteristics, have been observed in controlled conditions but have seldom been systematically examined in the field. In this work, A vs. C_i curves were measured over a 15 or 20 °C range of temperature in four C₃ species growing outdoors on two occasions about three weeks apart early in the growing season and also once near mid-season when air temperatures were more stable. The two early season occasions were chosen for having contrasting temperatures for 3 to 4 days preceding the measurements. Low temperatures (mean maximum/minimum temperatures of 19/11 °C) resulted in higher values of the V_Cmax of Rubisco and J_max at a given measurement temperature in most species compared with higher temperatures (max/min 31/25 °C). The apparent activation energy of V_Cmax of Rubisco ranged from 56 to 82 kJ mol⁻¹, and that of electron transport (J_max) ranged from 28 to 56 kJ mol⁻¹ across species and temperatures. In three of the four species, the activation energy of V_Cmax decreased and that of J_max increased after the cooler temperatures. Stomatal conductance measured at 20 and 25 °C increased strongly with the prior warm temperatures in all species. Measurements made near mid-season, after a period of relatively stable temperatures (mean maximum/minimum temperatures of 27/18 °C), also indicated a wide range of values of the activation energies of V_Cmax and J_max among these species. Full article

Salt stress is a major abiotic stress that interferes with plant growth and affects crop production. Dehydrin (DHN), a member of the late embryogenesis abundant (LEA) protein family, was considered to be a stress protein involved in the protective reaction of plant dehydration. Our previous research has shown that overexpression of the Suaeda salsa SsDHN gene enhances tolerance to salt stress in tobacco. However, the research on its protection in photosynthesis under salt stress remains unclear. In this study, gene overexpression (SsDHN-OE) tobacco plants were utilized to study the effect of the SsDHN gene on plant photosynthesis under salt stress. Our findings showed that overexpression of SsDHN increased the biomass, leaf area, root length, and root surface area in tobacco seedlings under salt stress conditions. The transgenic tobacco with overexpression of SsDHN had obvious stomatal closure, which effectively alleviated the adverse effects of salt stress on photosynthetic efficiency. Overexpression of the SsDHN gene in tobacco can effectively reduce the degree of photoinhibition and chloroplast damage caused by salt stress. Moreover, the SsDHN-overexpressing transgenic tobacco plants exhibited a decrease in oxidative damage and protected membrane structures related to photosynthesis by increasing antioxidant enzyme activity and antioxidant substance content. It was further found that the expression levels of photosynthetic and antioxidant-related genes Rubisco, SBPase, POD7, CAT3, APX2, and SOD3 were significantly up-regulated by overexpressing the SsDHN gene in tobacco seedlings under salt stress. In conclusion, the SsDHN gene might improve the salt stress resistance of tobacco seedlings and be involved in regulating photosynthesis and antioxidant activity under salt stress. Full article

Chemical weed control is a significant agricultural concern, and reliance on a limited range of herbicide action modes has increased resistant weed species, many of which use C4 metabolism. As a result, the identification of novel herbicidal agents with low toxicity targeting C4 plants becomes imperative. An assessment was conducted on the impact of 3-cyanobenzoic acid on the growth and photosynthetic processes of maize (Zea mays), a representative C4 plant, cultivated hydroponically over 14 days. The results showed a significant reduction in plant growth and notable disruptions in gas exchange and chlorophyll a fluorescence due to the application of 3-cyanobenzoic acid, indicating compromised photosynthetic activity. Parameters such as the chlorophyll index, net assimilation (A), stomatal conductance (g_s), intercellular CO₂ concentration (C_i), maximum effective photochemical efficiency (F_v′/F_m′), photochemical quenching coefficient (q_P), quantum yield of photosystem II photochemistry (ϕ_PSII), and electron transport rate through PSII (ETR) all decreased. The A/PAR curve revealed reductions in the maximum net assimilation rate (A_max) and apparent quantum yield (ϕ), alongside an increased light compensation point (LCP). Moreover, 3-cyanobenzoic acid significantly decreased the carboxylation rates of RuBisCo (V_cmax) and PEPCase (V_pmax), electron transport rate (J), and mesophilic conductance (g_m). Overall, 3-cyanobenzoic acid induced substantial changes in plant growth, carboxylative processes, and photochemical activities. The treated plants also exhibited heightened susceptibility to intense light conditions, indicating a significant and potentially adverse impact on their physiological functions. These findings suggest that 3-cyanobenzoic acid or its analogs could be promising for future research targeting photosynthesis. Full article

Basic inventory is required for proper understanding and utilization of Earth’s natural resources, especially with increasing soil degradation and species loss. Soil carbon is newly refined at >30,000 Gt C (gigatonnes C), ten times above prior totals. Soil organic carbon (SOC) is up to 24,000 Gt C, plus plant stocks at ~2400 Gt C, both above- and below-ground, hold >99% of Earth’s biomass. On a topographic surface area of 25 Gha with mean 21 m depth, Soil has more organic carbon than all trees, seas, fossil fuels, or the Atmosphere combined. Soils are both the greatest biotic carbon store and the most active CO₂ source. Values are raised considerably. Disparity is due to lack of full soil depth survey, neglect of terrain, and other omissions. Herein, totals for mineral soils, Permafrost, and Peat (of all forms and ages), are determined to full depth (easily doubling shallow values), then raised for terrain that is ignored in all terrestrial models (doubling most values again), plus SOC in recalcitrant glomalin (+25%) and friable saprock (+26%). Additional factors include soil inorganic carbon (SIC some of biotic origin), aquatic sediments (SeOC), and dissolved fractions (DIC/DOC). Soil biota (e.g., forests, fungi, bacteria, and earthworms) are similarly upgraded. Primary productivity is confirmed at >220 Gt C/yr on land supported by Barrow’s “bounce” flux, C/O isotopes, glomalin, and Rubisco. Priority issues of species extinction, humic topsoil loss, and atmospheric CO₂ are remedied by SOC restoration and biomass recycling via (vermi-)compost for 100% organic husbandry under Permaculture principals, based upon the Scientific observation of Nature. Full article

The Cd hyperaccumulator Solanum nigrum L. exhibits a cosmopolitan character and proven high and differentiated efficiency. This suggests the possibility of optimizing its Cd phytoremediation capacity and applicability through searching among remote ecotypes/genotypes. However, the extensive studies on this hyperaccumulator have been limited to Far East (Asian) regions. Pioneer pot experiments on the Middle European ecotype of S. nigrum within a concentration range of 0–50 mg kg⁻¹ Cd in soil revealed its Cd phytoremediation capacity to be comparable to Asian ecotypes but with a fundamentally different Cd tolerance threshold. While biomass of the Asian ecotypes declined sharply at C_soil ≈ 10 mg kg⁻¹ Cd, in the Middle European ecotype, a gradual mild biomass decrease occurred within the whole C_soil ≈ 0–50 mg kg⁻¹ Cd range with no toxic symptoms. Its adapted A50 variety was obtained from the seeds of first-generation plants grown in soil with C_soil ≈ 50 mg kg⁻¹ Cd. In this variety, Cd tolerance, accumulation performance, and all physiological parameters (chlorophyll, carotenoids, RuBisCO, and first- and second-line defense anti-oxidant activity) were significantly enhanced, while cell damage by ROS was considerably lesser. This makes the Middle European ecotype and its adapted variety A50 particularly useful to sustainable decontamination of heavily polluted “hot spots” in degraded post-industrial areas. Full article

Drought stress is a major environmental constraint that limits rice (Oryza sativa L.) production worldwide. In this study, we investigated the effects of drought stress at the booting stage on rice leaf physiological characteristics and yield. The results showed that drought stress would lead to a significant decrease in chlorophyll content and photosynthesis in rice leaves, which would affect rice yield. Three different rice varieties were used in this study, namely Hanyou73 (HY73), Huanghuazhan (HHZ), and IRAT109. Under drought stress, the chlorophyll content of all cultivars decreased significantly: 11.1% and 32.2% decreases in chlorophyll a and chlorophyll b in HHZ cultivars, 14.1% and 28.5% decreases in IRAT109 cultivars, and 22.9% and 18.6% decreases in HY73 cultivars, respectively. In addition, drought stress also led to a significant decrease in leaf water potential, a significant increase in antioxidant enzyme activity, and an increase in malondialdehyde (MDA) content, suggesting that rice activated a defense mechanism to cope with drought-induced oxidative stress. This study also found that drought stress significantly reduced the net photosynthetic rate and stomatal conductance of rice, which, in turn, affected the yield of rice. Under drought stress, the yield of the HHZ cultivars decreased most significantly, reaching 30.2%, while the yields of IRAT109 and HY73 cultivars decreased by 13.0% and 18.2%, respectively. The analysis of yield composition showed that the number of grains per panicle, seed-setting rate, and 1000-grain weight were the key factors affecting yield formation. A correlation analysis showed that there was a significant positive correlation between yield and net photosynthetic rate, stomatal conductance, chla/chlb ratio, Rubisco activity, and Fv/Fm, but there was a negative correlation with MDA and non-photochemical quenching (NPQ). In summary, the effects of drought stress on rice yield are multifaceted, involving changes in multiple agronomic traits. The results highlight the importance of selecting and nurturing rice varieties with a high drought tolerance, which should have efficient antioxidant systems and high photosynthetic efficiency. Future research should focus on the genetic mechanisms of these physiological responses in order to develop molecular markers to assist in the breeding of drought-tolerant rice varieties. Full article