Search Results (284)

Since the onset of industrialization, the safety of arable land has become a pressing global concern, with soil salinization emerging as a critical threat to agricultural productivity and food security. To address this challenge, the cultivation of economically valuable salt-tolerant plants has been proposed as a viable strategy. In the study, we investigated the physiological and molecular responses of Lycium ruthenicum Murr. to varying NaCl concentrations. Results revealed a concentration-dependent dual effect: low NaCl levels significantly promoted seed germination, while high concentrations exerted strong inhibitory effects. To elucidate the mechanisms underlying these divergent responses, a combined analysis of metabolomics and transcriptomics was applied to identify key metabolic pathways and genes. Notably, salt stress enhanced photosynthetic efficiency through coordinated modulation of ribulose 5-phosphate and erythrose-4-phosphate levels, coupled with the upregulation of critical genes encoding RPIA (Ribose 5-phosphate isomerase A) and RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase). Under low salt stress, L. ruthenicum maintained intact cellular membrane structures and minimized oxidative damage, thereby supporting germination and early growth. In contrast, high salinity severely disrupted PS I (Photosynthesis system I) functionality, blocking energy flow into this pathway while simultaneously inducing membrane lipid peroxidation and triggering pronounced cellular degradation. This ultimately suppressed seed germination rates and impaired root elongation. These findings suggested a mechanistic framework for understanding L. ruthenicum adaptation under salt stress and pointed out a new way for breeding salt-tolerant crops and understanding the mechanism. Full article

Ribulose bisphosphate carboxylase (RuBisCO) is the primary regulator of carbon fixation in the plant kingdom. Although the large subunit (RBCL) is the site of catalysis, RuBisCO efficiency is also influenced by the sequence divergence of the small subunit (RBCS). This project compared the RBCS gene family in C3 and C4 grasses to identify genetic targets for improved crop photosynthesis. Triticeae/Aveneae phylogeny groups exhibited a syntenic tandem duplication array averaging 326.1 Kbp on ancestral chromosomes 2 and 3, with additional copies on other chromosomes. Promoter analysis revealed a paired I-box element promoter arrangement in chromosome 5 RBCS of H. vulgare, S. cereale, and A. tauschii. The I-box pair was associated with significantly enhanced expression, suggesting functional adaptation of specific RBCS gene copies in Triticaeae. H. vulgare-derived pan-transcriptome data showed that RBCS expression was 50.32% and 28.44% higher in winter-type accessions compared to spring types for coleoptile (p < 0.05) and shoot, respectively (p < 0.01). Molecular dynamics simulations of a mutant H. vulgare Rubisco carrying a C4-like amino acid substitution (G59C) in RBCS significantly enhanced the stability of the Rubisco complex. Given the known structural efficiency of C4 Rubisco complexes, G59C could serve as an engineering target for enhanced RBCS in economically crucial crop species which, in comparison, possess less efficient Rubisco complexes. 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

Passion fruit (Passiflora edulis Sims), belonging to the Passifloraceae family, is an economically important plant in tropical and subtropical regions. The advances in functional genomics research of passion fruit have been significantly hindered by its recalcitrance to regeneration and stable transformation. This study establishes the first efficient Agrobacterium rhizogenes-mediated hairy root transformation system for passion fruit. Utilizing the eGFP marker gene, transformation efficiencies of 11.3% were initially achieved with strains K599, MSU440, and C58C1, with K599 proving most effective. Key transformation parameters were systematically optimized to achieve the following: OD₆₀₀ = 0.6, infection duration 30 min, acetosyringone concentration 100 μM, and a dark co-cultivation period of 2 days. The system’s utility was further enhanced by incorporating the red visual marker RUBY, enabling direct, instrument-free identification of transgenic roots via betaxanthin accumulation. Finally, this system was applied for functional analysis using PeMYB123, which may be involved in proanthocyanidin accumulation. Overexpression of PeMYB123 produced a higher content of proanthocyanidin in hairy roots. Additionally, the PeANR gene involved in the proanthocyanidin pathway was strongly activated in the transgenic hairy roots. This rapid and efficient visually simplified hairy root transformation system provides a powerful tool for functional gene studies in passion fruit. Full article

The response of plants to elevated atmospheric [CO₂] is highly dynamic and influenced by developmental stage, yet its role in photosynthetic acclimation remains underexplored. This study examines the physiological and molecular responses of wheat (Triticum durum, var. Amilcar) to elevated [CO₂] (700 ppm vs. 400 ppm) at two distinct developmental stages: the vegetative stage at the end of the elongation stage and the reproductive stage at the beginning of ear emergence (Z39 and Z51, respectively). Wheat plants at the developmental stage Z39, cultivated under elevated [CO₂], maintained photosynthetic rates despite a carbohydrate build-up. However, at Z51, photosynthetic acclimation became more evident as the decline in Rubisco carboxylation capacity (Vc_max) persisted, but also stomatal conductance and diffusion were decreased. This was accompanied by the up-regulation of the CA1 and CA2 genes, likely as a compensatory mechanism to maintain CO₂ supply. Additionally, hormonal adjustments under elevated [CO₂], including increased auxin and bioactive cytokinins (zeatin and isopentenyl adenine), may have contributed to delayed senescence and nitrogen remobilization, sustaining carbon assimilation despite biochemical constraints. These findings highlight the developmental regulation of photosynthetic acclimation, emphasizing the need for the stage-specific assessments of crop responses to future atmospheric conditions. Full article

The establishment of a transient expression system in petals is significant for elucidating gene functions in flowering trees characterized by a prolonged juvenile phase. Genetic improvements in Camellia japonica have been hindered due to the absence of a functional validation platform. In this study, we explored an Agrobacterium-mediated and readily observable transient expression system in camellia petals to systematically optimize four critical factors affecting transformation efficiency. As a result, the bud stage, ‘Banliuxiang’ genotype, OD600 of 1.0, and 1-day co-cultivation achieved the highest intensity of transient expression, and overexpression of the Ruby1 reporter gene induced substantial anthocyanin synthesis, manifested as distinct red pigmentation. Furthermore, the optimized transient expression system revealed that the R2R3-MYB transcription factor CjMYB5, which interacted with CjGL3, promoted anthocyanin biosynthesis in camellia petals by transactivating key DFR structural genes. This transient expression platform not only advances functional genomics studies in ornamental woody species but also lays a foundation for molecular breeding programs in C. japonica. 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

As one of the key processes of photosynthesis, carbon fixation and reduction is one of the most important biochemical reactions on planet Earth. Yet, reducing oxidized carbon elements through directly harnessing solar energy by using water-soluble, simple enzymes continues to be challenging. Here, CO₂ and bicarbonate were found to be transformed into methanol by fluorescent protein mRuby by using light as the single energy input. The binding of substrates to mRuby chromophore was supported by crystallography and light spectrometry. Gas chromatography showed the generation of methanol in mRuby-bicarbonate aqueous solution upon sunlight illumination. Atomic-resolution serial structures of mRuby showed snapshots of the step-by-step reduction of bicarbonate and CO₂. The amino, imino, or carboxylate group of residues near the chromophore was within hydrogen bonding distances of the substrates, respectively. A decrease in fluorescence was observed upon binding of bicarbonate, and the energy liberated from fluorescence was presumably utilized for methanol production. This research represents an exciting example of sunlight-driven photobiocatalysis by water-soluble small proteins. The new, green, and sustainable mechanisms uncovered here indicated great promises to harness solar energy straightforwardly, for, i.e., fuel production and green chemistry. Full article

Climate change imposes significant challenges on viticulture, especially in subtropical regions, where thermal and water stresses impact vine physiology and yield. This study evaluated the effects of two rootstocks (‘IAC 766 Campinas’ and ‘106-8 Mgt’) and two training systems (low and high trellis) on the photosynthesis, biochemical parameters, and productivity of Vitis labrusca (‘Bordô’ and ‘Isabel’). The interaction between rootstock and training system significantly influenced gas exchange, chlorophyll fluorescence, antioxidant enzyme activity, and yield components. In ‘Bordô’, grapevines trained on high trellis and grafted onto ‘IAC 766 Campinas’ showed a 45.1% higher electron transport rate and 39.8% greater total chlorophyll content at flowering compared to the low trellis and ‘106-8 Mgt’ combination. Productivity increased by 49% under this combination. In ‘Isabel’, low trellis combined with ‘IAC 766 Campinas’ enhanced water use efficiency by 50% and SPAD index by 11%. These results highlight that selecting suitable rootstock and training system combinations can optimize physiological efficiency and yield, representing an effective adaptation strategy for viticulture under subtropical conditions. 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