Search Results (609)

The first yellow-leafed crabapple variety developed in China is Malus ‘Duojiao’. The light level affects its leaf color. (1) Background: Plants are frequently shaded by photovoltaic panels and green buildings. It is unknown how genetic regulation and partial shadowing regulate leaf color. (2) Methods: Four 28-day shading treatments were used for ‘Duojiao’ crabapple and its maternal ‘Xifu’ crabapple. Virus-induced gene silencing (VIGS), overexpression transgenic validation experiments, and physiological index analysis were employed to identify the expression levels of significant candidate genes. (3) Results: Improvements in chlorophyll synthesis, mineral metabolism, and antioxidant status were observed. The net photosynthetic rate was 39.29% higher under double-layer shade than in the control. (4) Conclusions: Partial double-layer shading exhibited the optimal effect. MsCPOX was the key gene controlling leaf color. Our results provide a theoretical basis for analyzing light responses and determining genes regulating leaf color in crabapple. Full article

Alternate wetting and drying (AWD) is a crucial water-saving irrigation strategy in rice production, yet its regulatory mechanisms during drought–rewatering cycles remain unclear, particularly across recovery stages. Using a polyethylene glycol (PEG-6000) hydroponic system, we analyzed physiological, metabolomic, and transcriptomic responses of Oryza sativa L. ssp. japonica under control, continuous drought, and rewatering treatments. The net photosynthetic rate (P_n) recovered within one day after rewatering, and subsequently exceeded control levels, indicating a photosynthetic compensatory effect. In contrast, instantaneous water-use efficiency (WUE) showed only a transient increase before declining thereafter and remaining lower than under continuous drought, revealing an asynchronous recovery in which carbon assimilation precedes the recovery of transpiration. Metabolomic analysis indicated a shift from drought-induced accumulation to recovery-driven metabolic reprogramming, with coordinated up-regulation of central carbon metabolism and chlorophyll biosynthesis. Decreases in citrate, malate, and glutamate suggested their sustained utilization to support nitrogen assimilation and chlorophyll synthesis. Transcriptomic data further revealed large-scale reprogramming during late recovery, including up-regulation of nitrogen assimilation genes (e.g., NIA, NiR), linking carbon–nitrogen coordination with photosynthetic compensation. Overall, these results demonstrate that stage-specific integration of physiological recovery, metabolic restructuring, and transcriptional regulation underlies AWD-induced efficiency and identify early rewatering as a critical window for optimizing WUE. Full article

Chattonella marina is an ichthyotoxic, bloom-forming raphidophyte known for its hemolytic activity. However, the mechanisms by which nitrogen (N) and phosphorus (P) limitation influence this hemolytic toxicity remain poorly understood. In this study, both N and P limitation reduced growth, photosynthetic efficiency (F_v/F_m, Y_II, rETR_max), and the expression of nutrient-uptake, tetrapyrrole/chlorophyll biosynthesis genes. Nevertheless, the two nutrients produced opposite effects on toxicity: N limitation lowered hemolytic activity and ROS levels to near zero, whereas P limitation kept both relatively high, similar to nutrient-replete controls. The addition of the antioxidant NAC (N-Acetyl-L-cysteine) reduced hemolytic activity, confirming that ROS contributes to toxicity. Transcriptome data showed that under N limitation, genes for nitrogen uptake and initial reduction (NRT, NR, glnA) were upregulated, while downstream assimilation genes (nirA, GLT1) were downregulated. In contrast, under P limitation, all the nitrogen-metabolism-related genes (NRT, NR, glnA, nirA, GLT1) were downregulated. In the tetrapyrrole pathway, most genes were downregulated under both nutrient-limited conditions, except for HemD, suggesting a bottleneck that may result in the accumulation of porphyrin intermediates within the tetrapyrrole/chlorophyll biosynthesis pathway. Together, the secondary products derived primarily from the reaction of ROS with tetrapyrrole-based compounds appear to be the main contributors to hemolytic toxicity. Consequently, high levels of both ROS and porphyrin intermediates under P-limited conditions, as well as high ROS levels but low porphyrin intermediates under nutrient-sufficient conditions, may both contribute to the high hemolytic toxicity of C. marina. In contrast, under N limitation, despite the accumulation of porphyrin intermediates, the strong suppression of photosynthetic electron transport limits both ROS production and the synthesis of nitrogen-containing toxins, resulting in low hemolytic activity. These findings demonstrate that nutrient conditions regulate hemolytic activity in C. marina in a nutrient-specific manner. Full article

Hydrogen sulfide (H₂S) functions as a pivotal gaseous signaling molecule in plants, yet its role in promoting crop yield remains elusive. Here, we demonstrate that sodium hydrosulfide (NaHS) application, a donor of hydrogen sulfide (H₂S), significantly accelerates growth, promotes flowering, and enhances grain yield in rice (Oryza sativa L.). Optimal NaHS treatment increased plant height, root length, and biomass accumulation, concomitant with elevated sucrose, starch, chlorophyll contents, and nitrate reductase activity. Integrated transcriptomic and proteomic analyses revealed that NaHS reprograms key biological pathways, including photosynthesis, carbon metabolism, lipid metabolism, the hormone signal transduction pathway, and reactive oxygen species (ROS) homeostasis. NaHS also remodels fatty acid metabolism, significantly increasing unsaturated fatty acids, linoleic acid (C18:2n6c), and α-linolenic acid (C18:3n3)—the latter serving as the direct precursor for JA biosynthesis—thereby fueling jasmonic acid (JA) biosynthesis. NaHS treatment also induced ROS accumulation while simultaneously activating antioxidant enzymes, maintaining redox homeostasis, and promoting cell proliferation in root meristems. Transmission electron microscopy revealed that NaHS enlarges peroxisomes and increases chloroplast oil body number, linking organellar dynamics to enhanced JA synthesis and ROS signaling. Collectively, our findings establish NaHS as a novel chemical regulator that coordinates JA and ROS signaling to boost rice growth, flowering, and grain yield, offering a promising strategy to improve crop productivity. Full article

Chromium (Cr) contamination leads to the accumulation of Cr in crops, thereby posing a significant threat to food security and human health. It is essential to comprehend the mechanisms underlying Cr toxicity and to develop effective mitigation strategies to ensure healthy crop growth. Melatonin (MT), a multifunctional regulatory molecule, plays a pivotal role in the response of plants to heavy metal stress. This study is designed to investigate the underlying mechanisms through which exogenous application of MT mitigates the toxicity of Cr stress in maize seedlings. The findings of the study indicate that under Cr stress conditions, treatment with MT significantly decreased the Cr concentrations in the roots and leaves of maize, with reductions of 22% and 28.5%, respectively. Concurrently, MT demonstrated effectiveness in alleviating the toxic effects induced by Cr exposure, as evidenced by substantial improvements in the leaf area, chlorophyll content, and photosynthetic rate, which increased by 40.3%, 47.7%, and 64.8%, respectively. This led to a 42.2% increase in the total dry weight of maize. Further analysis indicates that MT modulates the antioxidant system, thereby reducing the production of reactive oxygen species and reducing membrane lipid damage associated with Cr toxicity. Moreover, MT upregulates the expression and activity of enzymes involved in polyamine synthesis while simultaneously inhibiting the activity of polyamine-degrading enzymes, leading to a 38% increase in total polyamine content. This study has enhanced our understanding of the mechanisms through which melatonin alleviates chromium toxicity in crops and has provided a theoretical foundation for its sustainable application in agricultural production. Full article

The guava tree (Psidium guajava L.) is a tropical fruit tree of worldwide importance; however, the salinity of irrigation water severely limits its development in semi-arid regions. However, magnesium (Mg) can mitigate this stress by promoting plant photosynthetic activity. The objective was to evaluate the effect of foliar Mg in mitigating saline stress on photosynthesis and the growth of guava cultivar seedlings. The experiment was conducted in a randomized complete block design, in a 2 × 2 × 3 factorial scheme, with two guava cultivars (Kumagai and Paluma), two irrigation water salinity levels (a low-salinity control—0.5 dS m⁻¹, and salt stress—2.5 dS m⁻¹), and three doses of foliar Mg (0, 1, and 2 mL L⁻¹), and six replications. A salinity of 2.5 dS m⁻¹ reduced growth and gas exchange in both cultivars, with a reduction of approximately 30% in total dry mass, and 16% in CO₂ assimilation rate. Supplementation with 1 mL L⁻¹ of Mg attenuated the effects of stress, stimulating chlorophyll synthesis and gas exchange, reducing approximately leaf temperature in 3.5%, and vapor pressure deficit (VPD) in 12%. The Paluma cultivar was more responsive to Mg under salinity, with improved CO₂ assimilation rate, stomatal control, and water use efficiency. Kumagai showed greater growth in height and diameter with 1 mL L⁻¹ under stress. Foliar application of magnesium (1 mL L⁻¹) is a promising strategy to produce guava seedlings under saline stress. Full article

Chroococcidiopsis sp. was isolated from the endolithic habitat of the Atacama Desert (northern Chile), one of the most challenging-to-life polyextreme environments on Earth. The photosynthetic machinery of microorganisms inhabiting this environment is supposed to be highly adapted to cope with the intense solar radiation of the area. Thus, PAR-red light ranging from 100 to 900 µmol photon·m⁻²·s⁻¹ has been investigated as a strategy to enhance culture productivity and stimulate the synthesis of bioactive molecules in Chroococcidiopsis sp. A control culture was maintained under white light at 100 µmol photon·m⁻²·s⁻¹. The results revealed that red light was utilized more efficiently than white light of similar irradiance, and its modulation enhanced both growth and photosynthetic activity of the cyanobacterium. Furthermore, Chroococcidiopsis sp. appeared to activate mechanisms to mitigate photooxidative stress produced by excess light energy. Specifically, increasing light irradiance induced photoacclimation responses, characterized by a decrease in chlorophyll content and a concomitant increase in carotenoid accumulation, likely aimed at reducing photon flux transduced to photosynthesis. Additionally, scytonemin synthesis was enhanced under high irradiances, contributing to dissipating excess light energy. Overall, this study demonstrates that modulation of red-light irradiance effectively improves the growth of Chroococcidiopsis sp. while promoting the accumulation of antioxidant compounds—primarily carotenoids and, to a lesser extent, scytonemin. Full article

Global freshwater resources face severe water quality degradation, with chlorophyll-a (Chl-a) concentration serving as a critical eutrophication indicator. While deep learning methods enable accurate Chl-a retrieval from remote sensing reflectance (Rrs) spectra, the scarcity of paired Rrs-Chl-a samples limits model generalization and causes overfitting, particularly in optically complex inland waters. To address this data bottleneck, we propose a physics-constrained latent diffusion model for synthesizing high-fidelity paired Rrs-Chl-a data to augment limited training sets for deep learning-based water quality retrieval. Our framework integrates three key innovations: (1) a lightweight variational autoencoder achieving 8.6:1 latent space compression, reducing computational overhead while preserving spectral features; (2) band-selective attention mechanisms targeting chlorophyll-sensitive wavelengths (440, 550, 680, and 700–750 nm) based on bio-optical principles; and (3) physics-guided conditional encoding that captures concentration-dependent spectral responses across oligotrophic to eutrophic regimes. Evaluated on the GLORIA dataset, our model demonstrates superior performance in spectral similarity (0.535), sample diversity (0.072), and distribution matching (Fréchet distance 0.0008) compared to conventional generative models. When applied to data augmentation, synthetic spectra improved downstream Chl-a retrieval from R²= 0.75 to 0.91, reducing RMSE by 39%. This physics-informed generative approach addresses data scarcity in aquatic remote sensing research, supporting global needs for enhanced understanding of inland and coastal water quality dynamics in data-limited regions. Full article

Satellite remote sensing has become essential for water quality assessment across inland and coastal environments, with rapid improvements in recent years. Significant advances have been made in detecting optically active parameters (such as chlorophyll-a, suspended matter, and turbidity), showing consistently strong performance across multiple studies. Specifically, the median validation performance (R²) derived from the quantitative synthesis indicates R² = 0.82 for chlorophyll-a (interquartile range—IQR: 0.75–0.90), R² = 0.80 for total suspended matter (IQR: 0.78–0.85), and R² = 0.88 for turbidity (IQR: 0.85–0.90). Conversely, the retrieval of optically inactive parameters (such as nutrients like total phosphorus and total nitrogen) remains more context dependent. It exhibits moderate, more variable results, with median R² = 0.68 (IQR: 0.64–0.74) for total phosphorus and R² = 0.75 (IQR: 0.70–0.80) for total nitrogen. These findings clearly illustrate the varying success of retrievals of optically active and inactive parameters and underscore the inherent difficulties of indirect estimation methods. However, high reported accuracy has yet to translate into transferable, uncertainty-informed, and operational monitoring systems. This gap stems from structural issues in validation design, physics integration, uncertainty management, and multi-sensor compatibility rather than data limitations alone. We present a PRISMA-guided, distribution-aware quantitative synthesis of 152 peer-reviewed studies (1980–2025), based on a systematic search protocol, to evaluate satellite-based retrievals of both optically active and inactive parameters. Instead of simply averaging performance, we analyse the empirical distributions of validation metrics, considering the validation protocol, sensor type, parameter category, degree of physics integration, and uncertainty quantification. The synthesis demonstrates that validation strategy often influences reported results more than the algorithm class itself, with accuracy inflated under non-independent cross-validation methods and notable variability between studies concealed by mean-based reports. Across four decades, four persistent structural challenges remain: limited transferability across sites and sensors beyond calibration areas; weak or implicit physical integration in many data-driven models; lack of or inconsistency in uncertainty quantification; and fragmented multi-sensor harmonisation that restricts operational scalability. To address these issues, we introduce two evidence-based coding frameworks: a physics-integration taxonomy (P0–P4) and an uncertainty-quantification hierarchy (U0–U4). Applying these frameworks shows that most studies remain focused on low-to-moderate levels of physics integration and primarily consider uncertainty at the prediction stage, with limited attention to upstream sources throughout the observation and inference process. Building on this structured synthesis, we propose a transferable, physics-informed, and uncertainty-aware conceptual framework that links model architecture, validation robustness, and probabilistic uncertainty to well-founded design principles. By shifting satellite water quality modelling from isolated algorithm demonstrations towards integrated, evidence-based system design, this study promotes scalable, decision-grade environmental monitoring amid the accelerating impacts of climate change. Full article

The aim of this study was to investigate how delayed fertilization with individual macronutrients (N, P, K, Ca, Mg, and S) affects the growth, yield components, biomass, and spectrophotometric indicators of spring wheat grown under controlled hydroponic conditions. Nutrient deprivation was initiated at BBCH stage 23 and maintained for 21, 28, 35, or 133 days, corresponding to BBCH stages 30, 32, 37, and 99, respectively. In selected treatments, the complete nutrient solution was subsequently restored until harvest to evaluate recovery potential. N, P, and Ca deprivation exerted the strongest negative effects on biomass accumulation across all deprivation durations. Compared to the fully supplied control, biomass was reduced by 60% under N deprivation and by 44.5% under P deprivation after 21 days. After 35 days, calcium deprivation resulted in a 97.7% reduction in biomass. Following 133 days of deprivation, biomass was reduced by 98%, 96.8%, and 95.9% under N, calcium, and P deficiencies, respectively. Root mass followed a similar pattern: after 21 days, it decreased by 52.46% (N) and 36.44% (P); after 28 days—by 57.4% (N) and 52.7% (P); after 35 days—by 90.7% (Ca), 66% (N), and 59.1% (P); and after 133 days—by 95.1–90.1% (Ca, N, P). Magnesium deprivation caused substantial reductions in growth parameters, reflecting its central role in chlorophyll structure and photosynthetic efficiency. Sulfur deprivation resulted in moderate but consistent biomass suppression and spectral divergence, indicating its importance in protein synthesis and redox regulation. Short-term deficiencies allowed partial recovery of growth and productivity, whereas long-term deprivation induced pronounced morphological alterations linked to stress adaptation. These effects were further confirmed through in vivo spectral reflectance measurements compared to healthy control plants. Full article

Granule-bound starch synthase (GBSS) is primarily recognized for its role in amylose production and starch granule formation in plant plastids. While its biochemical function in storage organs has been well documented, its broader contribution to plant growth and stress adaptation remains less defined. To explore these aspects, the maize gene ZmGBSS1 was ectopically expressed in Arabidopsis thaliana and its physiological effects were examined. Subcellular localization assays confirmed that ZmGBSS1 is specifically localized to chloroplasts. Phenotypic analysis of transgenic lines revealed that overexpression of ZmGBSS1 significantly altered early seedling development, promoted root elongation, and accelerated flowering, with flowering occurring approximately four days earlier than in wild-type plants. Changes in development were accompanied by increased starch accumulation, elevated amylose levels, and a higher abundance of enlarged starch granules within chloroplasts. Under drought and PEG-induced osmotic stress, transgenic plants maintained improved growth performance and recovery capacity, together with greater proline accumulation and chlorophyll retention. These physiological advantages coincided with more rapid starch utilization and clear rises in transcripts for proline synthesis enzymes (AtP5CS1, AtP5CS2) and starch-degrading proteins (AtBAM1, AtBAM3, AtDPE1). Collectively, these findings suggest that ZmGBSS1 not only regulates starch biosynthesis but also plays a crucial role in coordinating plant development and drought stress responses, highlighting its potential for improving stress tolerance through metabolic regulation. Full article

Selenium nanoparticles (SeNPs) synthesized through green routes have emerged as promising nanobiostimulants in sustainable agriculture due to their ability to enhance plant growth and antioxidant defense. The aim of this study was to evaluate the biostimulant effect of SeNPs on Capsicum annuum at two stages of crop development to characterize the response to SeNP exposure and identify concentration-dependent effects and application methods. Physiological indicators, including growth, photosynthetic pigment content, and antioxidant activity, were evaluated. Different concentrations of SeNPs were tested during germination, and dosage and two types of application were compared during the vegetative phase in a hydroponic experiment. SeNPs at concentrations of 1.25, 2.5, 5, 10, 20, 40, and 80 µM were applied to chili seeds for 20 days. The plants were exposed to SeNPs concentrations ranging from 1.25 to 80 µM, applied through the roots and leaves. Germination parameters were not significantly affected except for the seed vigor index, which increased at all concentrations, particularly at 20 µM. Low to moderate doses (1.25–20 µM) acted as biostimulants, enhancing plant height, root length, biomass accumulation, photosynthetic pigment content, and phenolic and flavonoid compound synthesis. Conversely, high doses (80 µM) induced phytotoxic effects, especially via root exposure, reflected by growth inhibition, and reduced chlorophyll content. Foliar application demonstrated a systemic biostimulant response, improving root growth and photosynthetic activity without toxicity symptoms. Antioxidant assays (DPPH and ABTS) revealed dose-dependent modulation of redox balance, suggesting adaptive responses to SeNP-induced oxidative conditions. These findings highlight the potential of SeNPs as biostimulants that improve physiological performance in chili plants, while emphasizing the importance of an optimal dosing and application method for sustainable nanotechnology-based crop management. Full article

In this study, we dissect the genetic effects of two major rice heading date genes, Heading date 1 (Hd1) and Grain number, plant height, and heading date 7 (Ghd7), in the regulation of six photosynthesis-related traits: the chlorophyll a/b contents, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), and transpiration rate (Tr). Using two sets of near-isogenic lines (Z43 and Z44) derived from a Zhenshan97/Milyang46 cross, functional Hd1 increased the chlorophyll contents but decreased the photosynthesis-related parameters; however, functional Ghd7 consistently inhibited all six traits. More importantly, there is a significant epistatic interaction between them: Hd1 only enhances the photosynthetic capacity under the non-functional background of ghd7 but intensifies its photosynthesis inhibition under the functional background of Ghd7. Transcriptome analysis showed that functional Ghd7 mainly down-regulated the expression of genes related to photosynthesis and chloroplast development, and the inhibitory effect was significantly enhanced in the presence of functional Hd1. GO enrichment analysis further confirmed that the chlorophyll synthesis, photosystem assembly, and electron transfer pathways were downregulated in the bifunctional allele combination. Although Hd1 promotes chlorophyll accumulation, it reduces the actual photosynthetic efficiency, indicating that it has different regulatory paths for chlorophyll synthesis and photosynthetic function. Both physiological and molecular evidence showed that the Hd1-Ghd7 module coordinated the regulation of the heading date and photosynthetic capacity, forming a trade-off relationship between “early heading–high photosynthesis” and “late heading–low photosynthesis”. This study reveals the pleiotropy of genes at the heading stage and provides a theoretical basis for the optimization of the source–sink balance in high-yield rice breeding. Full article

In the study of eggplant (Solanum melongena L.), a cross between the green peel line 19143 and the white peel line 19147 produced E4957 F₁ hybrids with a purple–brown peel. Self-fertilization of the F₁ hybrids yielded E4957 F₂ offspring with a segregation ratio of 27:9:21:7 among individuals with purple–brown, purple–red, green, and white peel colors, respectively, which was consistent with a genetic model controlled by reciprocal recessive epistasis between D and P, and Gv1 likely acting as a modifying factor. The green peel line 19143 exhibited higher chlorophyll but lower anthocyanin levels than the white peel line 19147, which contained low levels of both pigments, while the E4957 F₁ hybrids had elevated levels of both pigments. Two epistatic genes, D and P, associated with anthocyanin synthesis, were mapped on chromosomes 10 and 8, respectively. The putative modifying locus Gf, involved in chlorophyll accumulation in the flesh, was mapped on chromosome 8, and the localization interval was close to the previously reported Gv1 locus associated with chlorophyll synthesis in the peel. DNA markers (InDel22522, InDel5531, InDel-APRR2) were developed to genotype 237 F₂ individuals and correlate genotypes with phenotypes. Sequence analysis revealed a 6 bp deletion in the SmMYB1 (D) gene and a large deletion in the SmAPRR2-Like (Gv1) gene in the white peel line 19147, as well as a T to A mutation in the SmANS (P) gene in the green line 19143. This study provided evidence for inheritance between loci involved in anthocyanin and chlorophyll pathways contributing to eggplant peel color variation and provides molecular markers that may facilitate the breeding of eggplant varieties with diverse peel colors. Full article

Soil salinity in wheat represents a severe threat to global productivity, requiring a deep understanding of physiological adaptation mechanisms to ensure food security in the context of continuous agricultural land degradation. The study aim was to assess the impact of a salinity gradient (0–75 mM NaCl) on the dynamics of stomatal opening and chlorophyll content of the varieties Glosa, Taisa, Boema and Granny. The methodology integrated four joint classes, of which two were from detailed physiological parameters, stomatal features and chlorophyll content, and two morphological characteristics, growth visual indices and biomass allocation. All data was corroborated into an original hierarchical synthesis model presented in a multi-layered sunburst plot. The most relevant results indicate that the concentration of 45 mM NaCl represents the osmotic adjustment threshold, where the active accumulation of ions decreases the internal osmotic potential, facilitating an influx of water that maximizes guard cell turgor and, implicitly, stomatal width. Maximal physiological parameters and biomass ranked the variety Granny first, followed by Taisa. Despite stomatal increases, Boema ranked third and Glosa showed overall decreased development and the lowest plant biomass. These findings validate the use of interconnected effects analysis as a screening tool for identifying the salinity responses of wheat varieties. Full article