Search Results (446)

Parrotia subaequalis is a rare and endangered deciduous tree native to China, valued for its vibrant autumn foliage and ornamental appeal. Its leaves exhibit striking coloration, ranging from red to yellow and purple, yet the physiological and molecular mechanisms behind this variation remain poorly understood. Here, we combined transcriptomic, metabolomic, and physiological analyses to investigate pigment changes within the yellow leaf phenotype of P. subaequalis. Our findings revealed significant differences in gene expression and metabolic profiles between yellow and green leaves, particularly in starch and sucrose metabolism, photosynthesis, and carbon metabolism. Yellow leaves exhibited reduced photosynthetic capacity and carotenoid levels, alongside increased D-glucose concentration. These findings suggest that visible color transitions are likely driven by coordinated changes in carbohydrate metabolism, photosynthetic function, and organic compound accumulation. This study provides novel insights into the molecular and physiological mechanisms governing leaf pigmentation in an endangered tree, with useful information relevant to their conservation and sustainable utilization. Full article

Fe deficiency in apple trees can lead to leaf chlorosis and impede root development, resulting in significant alterations in signaling, metabolism, and genetic functions, which severely restricts fruit yield and quality. It is well established that WRKY transcription factors (TFs) are of vital significance in mediating plant responses to abiotic stress. Real-time quantitative fluorescence (RT-qPCR) analysis displayed that Fe deficiency stress can significantly induce WRKY69 TF gene expression. However, the potential mechanisms by which the WRKY69 gene involved in Fe deficiency stress remains to be investigated. To address this limitations, the WRKY69 gene (MD09G1235100) was successfully isolated from apple rootstock Malus halliana and performed both homologous and heterologous expression analyses in apple calli and tobacco to elucidate its functional role in response to Fe deficiency stress. The findings indicated that transgenic tobacco plants exhibited enhanced growth vigor and reduced chlorosis when subjected to Fe deficiency stress compared to the wild type (WT). Additionally, the apple calli that were overexpressed WRKY69 also exhibited superior growth and quality. Furthermore, the overexpression of the WRKY69 gene enhanced the ability of tobacco to Fe deficiency stress tolerance by stimulating the synthesis of photosynthetic pigments, increasing antioxidant enzyme activity, and facilitating Fe reduction. Additionally, it increased the resistance of apple calli to Fe deficiency stress by enhancing Fe reduction and elevating the activity of antioxidant enzymes. For example, under Fe deficiency stress, the proline (Pro) contents of the overexpression lines (OE-2, OE-5, OE-6) were 26.18 mg·g⁻¹, 26.13 mg·g⁻¹, and 26.27 mg·g⁻¹, respectively, which were 16.98%, 16.76%, and 17.38% higher than the proline content of 22.38 mg·g⁻¹ in the wild-type lines, respectively. To summarize, a functional analysis of tobacco plants and apple calli displayed that WRKY69 TF serves as a positive regulator under Fe deficiency stress, which provides candidate genetic resources for cultivating apple rootstocks or varieties with strong stress (Fe deficiency) resistance. Full article

The aim of this study was to evaluate whether intraspecific differences in zinc (Zn) tolerance and accumulation in the hyperaccumulator Noccaea caerulescens are linked to Zn-induced changes in transpiration and mineral composition. At 500 µM Zn in the nutrient solution, a decrease in the root and shoot biomass, the water content in roots, and the contents of photosynthetic pigments in shoots was observed only in the non-metallicolous population Wilwerwiltz, whereas in the calamine population Prayon, root growth was stimulated. Zinc-induced impairment of mineral nutrition was greater in Wilwerwiltz than in Prayon, which determined the manifestation of Zn toxicity in Wilwerwiltz. The absence of signs of Zn toxicity and the stimulation of root growth in Prayon may be due to lower Zn accumulation in Prayon than in Wilwerwiltz, as well as more effective mechanisms of Zn detoxification. The higher Zn content in the shoots and, in particular, in the water-storage cells of the leaf epidermis in Wilwerwiltz compared to Prayon may be partly due to the higher transpiration rate in Wilwerwiltz, at least at 500 µM Zn. These findings suggest that the metallicolous population maintains better control over Zn accumulation, which may be a part of the adaptive response to Zn-enriched media. Full article

Selenium (Se), as a vital trace element, plays an important role in regulating the antioxidant systems of plants, strengthening photosynthetic capacity, and enhancing their stress resistance. Selenate and selenite are the dominant forms of Se available to plants in soils. This research takes highland barley as the research object, aiming to assess the impacts of plant growth, organic acid metabolite, and six transcription factor families in highland barley seedlings under varying concentrations of Na₂SeO₃. The study indicated that compared to the control group (CK), the plant height of highland barley seedlings under Se1 (0.02 g/kg Na₂SeO₃) treatment significantly increased by 66%. Under the Se2 (0.2 g/kg Na₂SeO₃) treatment, plant height significantly decreased by 28%. With Na₂SeO₃ concentration increased, the pigment content, O₂⁻ production rate, and soluble protein content in highland barley seedlings decreased, while the contents of soluble sugar, MDA, and H₂O₂ increased. Se1 treatment was found to be more beneficial for the growth and development of seedlings. The organic selenium in leaves and roots under Se2 treatment significantly increased by 1105-fold and 188-fold, respectively. The most effective migration capability from soil to leaf under Se1 or Se2 treatment was up to 6.15 or 6.56, respectively. Based on metabolomics, 30 differential metabolites of organic acids were screened from highland barley seedlings under Na₂SeO₃ treatment and showed positive correlationships with organic selenium, inorganic selenium, and total selenium in highland barley seedling leaves. Through transcriptome analysis, heatmap analysis on six major categories of transcription factors (bHLH, MYB, NAC, WRKY, GATA, and HSF) was performed. Under Se2 treatment, approximately two-thirds of the transcription factors showed high expressions. We further screened 26 differentially expressed genes (DEGs) related to Na₂SeO₃ concentration. Based on correlation analysis, there were six genes in the bHLH family, five in MYB, three in NAC, five in WRKY, and three in the GATA and HSF families that showed positive correlations with 30 differential organic acid metabolites. These results enhance our understanding of the relationship between the organic acid metabolites and transcription factor expression in highland barley seedlings under Na₂SeO₃ treatment. Full article

Invasive alien species are one of the main threats to global biodiversity, and pose significant management challenges in several areas outside their natural range. In southern Mediterranean Europe, the invasion of Acacia species is particularly severe and its control requires costly and often ineffective actions. The use of vermicompost derived from these species to replace peat-based substrates in horticulture offers a promising alternative to mitigate their economic and environmental impacts while enhancing the sustainability of their control. This study explored the potential of vermicompost produced from the fresh aboveground waste biomass (leaves + stems + flowers) of Acacia dealbata and Acacia melanoxylon (75:25 w/w), two of the most aggressive Acacia species in the Mediterranean, using Eisenia fetida over twelve weeks. In essence, this study aimed to evaluate the quality of the produced vermicompost and its suitability as a partial substitute for potting substrate in the production of cucumber (Cucumis sativus) seedlings for transplant. Four substrate mixtures containing 0%, 10%, 30%, and 50% of Acacia vermicompost (w/w), combined with commercial peat-based potting substrate and perlite (20%) were tested in polystyrene seedling trays. Seedling emergence, growth, and leaf biochemical parameters (photosynthetic pigments, phenolics, soluble sugars and starch, and total thiobarbituric acid-reactive substances—TBARSs) were evaluated. The results showed that the addition of Acacia vermicompost to the commercial substrate did not affect its germination but significantly enhanced seedling growth, particularly in mixtures containing 30% and 50% Acacia vermicompost. In addition, the absence of accumulation of TBARSs also reflected the superiority of these two treatments. These findings suggest that vermicompost derived from A. dealbata and A. melanoxylon biomass can be a viable peat-based substrate alternative for horticultural production, with the dual benefit of promoting sustainable agricultural practices and contributing to invasive species management. Full article

Conventional micropropagation of cannabis struggles with excessive callus hyperhydration, slow growth, low rooting efficiency, and high contamination risk, all of which greatly restrict its feasibility for large-scale propagation. In contrast, photoautotrophic micropropagation (PAM) has emerged as an efficient and cost-effective propagation strategy that can significantly enhance plantlet growth and improve seedling quality by optimizing the LED lighting environment. This study investigated the effects of four light intensities (50, 100, 150, and 200 µmol m⁻² s⁻¹) and three photoperiods (16, 20, and 24 h d⁻¹) on the growth and rooting of two medicinal cannabis cultivars (the short-day cultivar ‘Charlotte’ and the day-neutral cultivar ‘Auto Charlotte’). Cluster analysis revealed that plantlets grown under the photoperiod of 20 h d⁻¹ and light intensity of 100–150 µmol m⁻² s⁻¹ exhibited optimal growth performance in terms of plant height, root length, leaf number, leaf area, biomass, and root activity. Moreover, increasing the light intensity from 50 to 100–150 µmol m⁻² s⁻¹ significantly enhanced net CO₂ exchange rates by 41.5% and 204.9% for Charlotte and Auto Charlotte, respectively, along with corresponding increases in dry matter accumulation of 44.3% and 27.9%. However, the plantlets exhibited photooxidative damage under continuous lighting and light intensity of 200 µmol m⁻² s⁻¹, as evidenced by reduced photosynthetic pigment content and suppressed antioxidant enzyme activity. Therefore, PAM of medicinal cannabis is recommended under the LED lighting environment with light intensity of 100–150 µmol m⁻² s⁻¹ and photoperiod of 20 h d⁻¹ to achieve optimal growth and rooting. These findings provide essential technical support for the large-scale propagation of vigorous, disease-free female plantlets with well-developed root systems and high genetic uniformity, thereby meeting the stringent quality standards for planting materials in the commercial cultivation of cannabis for medical and pharmaceutical use. Full article

Egypt’s rapid population increase has resulted in higher water demand. It may significantly reduce the amount of water available for agriculture, increasing the chance of using saline water in agriculture. Using saline water certainly poses a major threat to maize growth and may severely affect the growth and productivity of this important crop. Therefore, the aim of this study was to isolate newly native salt-tolerant bacteria from Egyptian saline soils and assess their ability to produce growth-promoting substances under salinity stress, as well as test the mitigating impact of these isolated salt-tolerant bacteria along with arbuscular mycorrhizal fungi (AMF) in maize plants under salinity stress. We isolated ninety-seven salt-tolerant bacterial isolates, and these isolates show a high ability to grow under different concentrations of NaCl. The nine most efficient isolates show a high ability to produce indole acetic acid (IAA), gibberellic acid (GA), P-solubilized exopolysaccharides (EPS), proline, and antioxidants under different NaCl concentrations. Using the 16S rRNA gene, the most effective isolate STB 89 was identified, and its impact, along with AMF, on the growth of salinity-stressed maize was tested in a pot experiment. Our results showed that the growth parameters (shoot length, root length, dry weight, and leaf area), photosynthetic-related pigments (Chlorophyll a, b, and carotenoids), NPK content, and antioxidant enzymes (PPO, POX, and CAT) were improved significantly at p ≤ 0.05 due to the bioinoculant applications, while reduced proline accumulation, Na uptake, and the Na⁺/K⁺ ratio in maize plant tissues were observed compared to the control plants. Moreover, the indices of AMF colonization in maize roots and the count of bacteria in the rhizosphere were enhanced due to the bioinoculant applications under salinity stress. In addition, we found that the combined application was more pronounced than the individual application impact. Hence, our results recommended that salt-tolerant bacteria (STB 89) could support salinity, mitigating the impact of AMF in maize plants, as well as allowing better practical techniques for maize cultivation and soil sustainability under salinity stress. Full article

Leaf colour is a valuable morphological phenotype for studying plant metabolism and physiology. To elucidate the mutation mechanism of leaf colour variation in maize, we compared the ethyl methylsulfonate (EMS)-induced maize mutant zmpgl, which has light green leaves, with the wild-type maize line B73. At the seedling stage, the zmpgl mutant presented distinct light green leaf colouration. Comprehensive analyses revealed that both the photosynthetic parameters and pigment contents of the mutant seedlings were significantly lower than those of the wild-type seedlings. Transmission electron microscopy of the mutant leaves revealed alterations in the chloroplast structure, which consequently impaired the photosynthetic efficiency and accumulation of organic matter. Through integrated transcriptomic and metabolomic profiling, we identified differentially expressed genes (DEGs) and differentially abundant metabolites associated with the zmpgl phenotype. These molecular components were associated with pathways related to plant metabolism, chloroplast structure-associated hormone signalling, and redox homeostasis. Further investigation revealed a significant differential expression of genes involved in several critical biological processes, including tetrapyrrole synthesis, lipid metabolism (related to leaf photosynthesis), amino acid metabolism (associated with chlorophyll synthesis and the light response), and abscisic acid (ABA) biosynthesis. These processes are crucial for plant photosynthesis, respiration, and catalytic functions. This study not only provides a valuable resource for further investigation of plant photosynthetic systems but also establishes a foundational framework for the comprehensive functional characterisation of genes involved in the leaf colour change in the zmpgl mutant. These findings contribute to our understanding of the molecular basis of leaf colour variation and its impact on photosynthetic performance in maize. Full article

Submerged macrophytes play a crucial role in the ecological restoration of aquatic environments, and enclosed plot planting technology is one of the economical and effective methods to establish submerged macrophyte communities in high-turbidity water bodies. This study focused on Vallisneria spinulosa Yan (V. spinulosa), examining the impact mechanism of planting density on the water restoration effectiveness of V. spinulosa growth systems constructed within enclosed plots, based on its growth and physiological characteristics as well as the water purification effects of its growth system. The research results indicate that low to medium planting densities (50–100 plants/m²) favor leaf elongation and expansion, as well as the growth of root diameter, surface area, and volume, while high densities (150–200 plants/m²) inhibit leaf and root growth. The content of photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids) in V. spinulosa increased with planting density. At high densities, significant increases in superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) levels in V. spinulosa suggest enhanced antioxidant activity. High protein content at low densities indicates stronger metabolic activity. Medium planting density (100 plants/m²) had significant effects on increasing dissolved oxygen (DO), regulating pH, and reducing electrical conductivity (EC), and exhibited the optimum removal loadings for total phosphorus (TP), phosphate (PO₄³⁻-P), total nitrogen (TN), and nitrate (NO₃⁻), achieving the average value of 0.44, 0.42, 6.94, 0.83 mg m⁻² d⁻¹. The findings of this study can provide a theoretical basis and technical support for practical ecological restoration projects involving submerged macrophytes in aquatic environments. Full article

Alginate oligosaccharides (AOSs) have been shown to be effective in enhancing crop growth. However, their functions in horticulture crops and growth-promoting mechanisms remain insufficiently characterized. This study employed pot cultivation experiments to investigate the effects of AOS root drenching (0, 15, 30, 45 mg·L⁻¹) on tomato (Solanum lycopersicum L.) seedling growth, photosynthetic performance, and phytohormone accumulation. The results showed that AOS promoted the leaf count per plant, leaf area of the youngest fully expanded leaves, shoot and root dry mass, chloroplast pigment contents and photosynthetic rate of tomato seedlings. And the 30 mg·L⁻¹ treatment consistently showed optimal efficacy, in which tomato seedlings also exhibited a significantly longer total root length, a larger root surface area and a greater number of root tips compared to the control. Phytohormone profiling revealed that AOS differentially regulated shoot/root phytohormones as follows: increasing auxins/cytokinins (CKs)/GA₁₉ content in shoots and Indole-3-acetic acid (IAA)/CKs/1-aminocyclopropane-1-carboxylic acid (ACC) content in roots, while decreasing root Jasmonic acid (JA)/5-deoxystrigol (5DS) contents. Finally, these findings demonstrate that AOS enhances tomato growth by coordinately reprogramming phytohormone homeostasis. Full article

The necessity of optimizing the nutrient and water efficiency in conventional hydroponics and enhancing their sustainability has given rise to the concept of cascade cropping systems. These achieve high water and resource use efficiencies, together with a lower environmental footprint, which is especially important for Mediterranean areas. However, scientific questions about the mechanisms that drive productivity in this system remain to be answered. This study aimed at a comprehensive evaluation of crop performance in cascade systems in terms of morphoanatomical and functional responses, also including product quality parameters, which influence the marketability of the fruit. In a three-month experiment, the dynamics of melon’s photosynthetic light use efficiency, pigment contents, growth parameters, and leaf compactness were assessed in a cascade system using drainage of tomato cultivation in comparison to classic hydroponic melon. The fruits’ chroma, hardness, total soluble solids, and pH were also measured. Comparable plant functional responses in the control and cascade melon plants resulted in similar growth and morphoanatomical traits. The fruit quality attributes were also found to be almost identical. It is proposed that the cascade system is both effective and sustainable in regions facing climatic and water scarcity pressures, such as those that are prevalent around the Mediterranean basin. Full article

Background/Objectives: Globally, antibiotic contamination has become an emerging issue in agricultural lands. The presence of antibiotic residues in farmlands, especially through the application of manure fertilizers containing veterinary antibiotics, e.g., tetracycline (TC), can cause severe toxicity, which inhibits crop growth and performance, subsequently threatening human health via consumption of contaminated products. This study was conducted to evaluate the phytotoxicity of TC on Kimchi cabbage (Brassica campestris L.) during seed germination, seedling, and vegetative growth stages, along with its physiological responses and bioaccumulation under TC stress. Methods: The responses of cabbage plants to TC stress were assessed through a germination test and a pot experiment, conducted for three days and six weeks, respectively, under different doses of TC (0, 5, 10, 25, and 50 mg/L). Results: As a result of the germination test, higher TC doses (25 and 50 mg/L) tended to delay seed germination, but all treatments achieved a 100% germination percentage by Day 3 after sowing. Eight days after sowing, the length of shoots and roots of seedlings exhibited a TC dose-dependent decline, specifically under 50 mg TC/L, showing a considerable decrease of 24% and 77%, respectively, compared to control. Similar results were observed in the plants transitioning from the seedling to vegetative stages in the pot experiment. Four and six weeks after sowing, the 50 mg TC/L dose showed the strongest phytotoxicity in cabbage plants with physiological parameters, such as the maximum photosystem II quantum yield (F_v/F_m), pigment content (chlorophyll and carotenoid), biomass, and leaf number, significantly reduced by 26 to 60% compared to control. Interestingly, at lower TC doses (5 and 10 mg/L), a hormesis effect was observed in the phenotype and biomass of the plants. In addition, the degree of TC accumulation in the plants was highly dose-dependent at Week 4 and Week 6, but a temporal decline in TC accumulation was noted between these time points in all TC treatments. This phenomenon might affect the value of the bio-concentration factor (BCF) as an indicator of the plant’s tendency to uptake TC. That is, in Week 6, the dose-dependent reduction in BCF for TC in the plants was likely attributed to a dilution effect caused by plant biomass increase or a degradation mechanism within the plant. Conclusions: Overall, our findings suggest that tetracycline toxicity induces seed germination delay and influences seedling elongation and photosynthetic functions, ultimately impairing crop growth and performance. Also, the antibiotic dynamics related to accumulation and degradation in plants were identified. These results will not only suggest the toxicity threshold of TC for cabbage but also provide insights into effective soil management strategies for food production safety and agroecosystem sustainability in antibiotic-contaminated soils. Full article

Scallions are a highly valued leafy vegetable and are enjoyed worldwide due to their appealing taste and nutritional benefits. A combination of short cultivation cycles and high market demand not only enhances food security but also offers a profitable opportunity for growers. In our study, we aim to evaluate the effect of increasing boron (B) applications, specifically 0, 0.2, 0.4, 0.8, 1.2, and 1.6 mM B supplied as boric acid (H₃BO₃) in the nutrient solution, on several key physiological and agronomic parameters in scallions. Results showed that the effects of increasing B levels on biomass production were insignificant, but the root fresh weight (FW) significantly decreased with all B levels. Higher B levels (1.2 and 1.6 mM) caused decreases of 22.9% and 29.6%, respectively. The effects of all B levels on photosynthetic pigment contents [chlorophyll (Chl) a, b, a + b, and carotenoid (Car)], root and shoot membrane permeability (MP), and root, shoot, and leaf nutritional status [phosphorus (P), potassium (K), calcium (Ca), and sodium (Na) concentrations] were found insignificantly. However, all B levels caused a significant increase in the B concentrations of the root, shoot, and leaf of scallions and plants translocated the majority of applied B into their leaves. The translocation factor (TF) of B from the root to the leaf was found to be 138.2%, 133.3%, and 107.3% with 0.8, 1.2, and 1.6 mM B levels, respectively. Moreover, plants exposed to high levels of B showed no significant response or toxicity symptoms. We concluded that B is a phloem mobile element in onion, a non-graminaceous monocotyledonous plant, and therefore accumulates in the upper organs but illustrates partial toxicity symptoms in leaves. Studies with higher B concentrations could be recommended to determine critical B levels for green onion production in B-contaminated areas. Full article

Soil salinity is a major constraint on crop cultivation, affecting millions of hectares of land and increasing drastically worldwide. Identifying sources of tolerance within the crops and their wild relatives is imperative. Recently, Solanum dasyphyllum L. has been identified as source of tolerance to drought for eggplant (S. melongena L.). In this article, the potential use of S. dasyphyllum as a source of tolerance to salinity is investigated through the characterization of young plants’ performance under three salt stress treatments, well water (control), as well as 200 mM and 400 mM NaCl. Biometric parameters such as leaf and radicular biomass, plant height, root length, and biochemical parameters—such as photosynthetic pigments, main ions accumulation, proline, total soluble sugars, malondialdehyde, total phenolics, flavonoids, and antioxidant enzymes’ activity—were quantified. The results showed a certain reduction in leaf and stem plant growth up to 60% in response to extreme salinity, while root biomass was maintained under mid-salt stress. Salt stress caused toxic ions to accumulate in plant organs, up to 1600 mmol g⁻¹ dry weight Na⁺ and a 2250 mmol g⁻¹ dry weight Cl⁻ in leaves under extreme salinity exposure. However, S. dasyphyllum maintained K⁺ levels at around 450 mmol g⁻¹ in leaves and roots and 750 mmol g⁻¹ in stems, indicating a mechanism related to ion transport to cope with ion toxicity. The biochemical response indicated osmotic adjustments and antioxidant activity without the need of activating antioxidant enzymes. S. dasyphyllum has proved to be a valuable genetic tool for new eggplant breeding programs regarding salt stress, with somewhat improved performance regarding biometric parameters and ion transport. Full article

Maize is very sensitive to salt stress during seed germination and seedling growth periods, which can seriously affect the development of the maize industry. In this study, we applied exogenous melatonin (MT) to treat maize seeds and seedlings to investigate the alleviation mechanism of salt damage in maize. Phenotypic analyses showed that 100 µmol/L MT alleviated the effects of salt stress on maize seed germination, and germination index and vigor index were increased compared with salt treatment. MT also alleviated the effects of salt stress on biomass and photosynthesis of maize seedlings, and at a concentration of 100 µmol/L, root and shoot lengths were increased, Gs and Tr were significantly elevated, and LWUEint and LWUEins were decreased. MT also scavenged ROS accumulation, reduced MDA, H₂O_2, and O₂⁻ production, and increased antioxidant enzyme activities and osmoregulatory substances in maize seedlings, but too high a concentration exacerbated oxidative and osmotic stresses. In addition, MT reduced Na⁺ content and increased K⁺ content in leaves and roots of maize seedlings. The principal components analysis explained 99.1% of the total variance in the first two axes (PC1 and PC2), and the differences between the treatment groups along the PC1 and PC2 axes were obvious. Correlation analysis elucidated the correlation between the indicators. Random forest analysis showed that different treatments had significant effects on germination percentage (GP), free proline (FP), CAT, and leaf intrinsic water use efficiency (LWUEint). Partial least squares analysis showed that photosynthetic parameters and pigment content played an important role in the salt tolerance of maize seedlings. In conclusion, the application of exogenous MT can effectively alleviate the negative effects of salt stress on the growth of maize seeds and seedlings, especially at a concentration of 100 µmol/L, which is the most effective. Full article