Regulatory Mechanism through Which Old Soybean Leaves Respond to Mn Toxicity Stress.

Manganese (Mn) is a heavy metal that can cause excessive Mn poisoning in plants, disrupting microstructural homeostasis and impairing growth and development. However, the specific response mechanisms of leaves to Mn poisoning have not been fully elucidated. This study revealed that Mn poisoning of soybean plants resulted in yellowing of old leaves. Physiological assessments of these old leaves revealed significant increases in the antioxidant enzymes activities (peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT)) and elevated levels of malondialdehyde (MDA), proline, indoleacetic acid (IAA), and salicylic acid (SA), under 100 µM Mn toxicity. Conversely, the levels of abscisic acid (ABA), gibberellin 3 (GA3), and jasmonic acid (JA) significantly decreased. The Mn content in the affected leaves significantly increased, while the levels of Ca, Na, K, and Cu decreased. Transcriptome analysis revealed 2258 differentially expressed genes in the Mn-stressed leaves, 744 of which were upregulated and 1514 were downregulated; these genes included genes associated with ion transporters, hormone synthesis, and various enzymes. Quantitative RT-PCR (qRT-PCR) verification of fifteen genes confirmed altered gene expression in the Mn-stressed leaves. These findings suggest a complex gene regulatory mechanism under Mn toxicity and stress, providing a foundation for further exploration of Mn tolerance-related gene regulatory mechanisms in soybean leaves. Using the methods described above, this study will investigate the molecular mechanism of old soybean leaves' response to Mn poisoning, identify key genes that play regulatory roles in Mn toxicity stress, and lay the groundwork for cultivating high-quality soybean varieties with Mn toxicity tolerance traits.

Alpha lipoic acid mitigates adverse impacts of drought stress on growth and yield of mungbean: photosynthetic pigments, and antioxidative defense mechanism.

Context: Exogenous use of potential organic compounds through different modes is a promising strategy for the induction of water stress tolerance in crop plants for better yield. Aims: The present study aimed to explore the potential role of alpha-lipoic acid (ALA) in inducing water stress tolerance in mungbean lines when applied exogenously through various modes. Methods: The experiment was conducted in a field with a split-plot arrangement, having three replicates for each treatment. Two irrigation regimes, including normal and reduced irrigation, were applied. The plants allocated to reduced irrigation were watered only at the reproductive stage. Three levels of ALA (0, 0.1, 0.15 mM) were applied through different modes (seed priming, foliar or priming+foliar). Key results: ALA treatment through different modes manifested higher growth under reduced irrigation (water stress) and normal irrigation. Compared to the other two modes, the application of ALA as seed priming was found more effective in ameliorating the adverse impacts of water stress on growth and yield associated with their better content of leaf photosynthetic pigments, maintenance of plant water relations, levels of non-enzymatic antioxidants, improved activities of enzymatic antioxidants, and decreased lipid peroxidation and H2O2 levels. The maximum increase in shoot fresh weight (29% and 28%), shoot dry weight (27% and 24%), 100-grain weight (24% and 23%) and total grain yield (20% and 21%) in water-stressed mungbean plants of line 16003 and 16004, respectively, was recorded due to ALA seed priming than other modes of applications. Conclusions: Conclusively, 0.1 and 0.15 mM levels of ALA as seed priming were found to reduce the adverse impact of water stress on mungbean yield that was associated with improved physio-biochemical mechanisms. Implications: The findings of the study will be helpful for the agriculturalists working in arid and semi-arid regions to obtain a better yield of mungbean that will be helpful to fulfill the food demand in those areas to some extent.

A study on nickel application methods for optimizing soybean growth.

Fertilization with nickel (Ni) can positively affect plant development due to the role of this micronutrient in nitrogen (N) metabolism, namely, through urease and NiFe-hydrogenase. Although the application of Ni is an emerging practice in modern agriculture, its effectiveness strongly depends on the chosen application method, making further research in this area essential. The individual and combined effects of different Ni application methods-seed treatment, leaf spraying and/or soil fertilization-were investigated in soybean plants under different edaphoclimatic conditions (field and greenhouse). Beneficial effects of the Soil, Soil + Leaf and Seed + Leaf treatments were observed, with gains of 7 to 20% in biological nitrogen fixation, 1.5-fold in ureides, 14% in shoot dry weight and yield increases of up to 1161 kg ha-1. All the Ni application methods resulted in a 1.1-fold increase in the SPAD index, a 1.2-fold increase in photosynthesis, a 1.4-fold increase in nitrogenase, and a 3.9-fold increase in urease activity. Edaphoclimatic conditions exerted a significant influence on the treatments. The integrated approaches, namely, leaf application in conjunction with soil or seed fertilization, were more effective for enhancing yield in soybean cultivation systems. The determination of the ideal method is crucial for ensuring optimal absorption and utilization of this micronutrient and thus a feasible and sustainable management technology. Further research is warranted to establish official guidelines for the application of Ni in agricultural practices.

Synergistic effect of seaweed extract and boric acid and/or calcium chloride on productivity and physico-chemical properties of Valencia orange.

Many citrus species and cultivars are grown successfully in tropical and subtropical countries, as well as in arid and semi-arid regions with low levels of organic matter and low cation exchange, resulting in lower nutrient uptake by the plant. The essential nutrients needed for citrus flowering and fruit set are limited in winter due to a reduction in transpiration rate, negatively effecting vegetative growth, flowering, yield, and fruit quality. The present investigation was carried out to assess the nutritional status, fruit yield parameters, and fruit quality of Valencia orange trees after foliar spraying of seaweed extract (SW) combined with calcium chloride and boric acid and their combinations in the 2020/2021 and 2021/2022 seasons. The treatments were arranged in a split-plot design (three levels spraying seaweed extract × four levels spraying calcium chloride and boric acid and their combinations × four replicates × one tree/replicate). The results indicated that all of the characteristics measured, including leaf chlorophyll, leaf mineral contents, fruit yield parameters, fruit physical properties, and fruit chemical properties, were significantly affected by the foliar spraying of seaweed extract (SW) combined with calcium chloride and boric acid and their combinations. Although all treatments increased the productivity and the physical and chemical properties of Valencia orange fruits compared to the control, a treatment of 10 g/L SW combined with 0.5 g/L boric acid and 1 g/L calcium chloride produced superior results. This ratio of SW, boric acid, and calcium chloride is therefore recommended to enhance productivity and improve the physico-chemical properties of Valencia orange for greater fruit yield.

Strigolactones promote flowering by inducing the miR319-LA-SFT module in tomato.

Strigolactones are a class of phytohormones with various functions in plant development, stress responses, and in the interaction with (micro)organisms in the rhizosphere. While their effects on vegetative development are well studied, little is known about their role in reproduction. We investigated the effects of genetic and chemical modification of strigolactone levels on the timing and intensity of flowering in tomato (Solanum lycopersicum L.) and the molecular mechanisms underlying such effects. Results showed that strigolactone levels in the shoot, whether endogenous or exogenous, correlate inversely with the time of anthesis and directly with the number of flowers and the transcript levels of the florigen-encoding gene SINGLE FLOWER TRUSS (SFT) in the leaves. Transcript quantifications coupled with metabolite analyses demonstrated that strigolactones promote flowering in tomato by inducing the activation of the microRNA319-LANCEOLATE module in leaves. This, in turn, decreases gibberellin content and increases the transcription of SFT. Several other floral markers and morpho-anatomical features of developmental progression are induced in the apical meristems upon treatment with strigolactones, affecting floral transition and, more markedly, flower development. Thus, strigolactones promote meristem maturation and flower development via the induction of SFT both before and after floral transition, and their effects are blocked in plants expressing a miR319-resistant version of LANCEOLATE. Our study positions strigolactones in the context of the flowering regulation network in a model crop species.

Effect of methyl jasmonate and GA3 on canola (Brassica napus L.) growth, antioxidants activity, and nutrient concentration cultivated in salt-affected soils.

Salinity stress is a significant challenge in agricultural production. When soil contains high salts, it can adversely affect plant growth and productivity due to the high concentration of soluble salts in the soil water. To overcome this issue, foliar applications of methyl jasmonate (MJ) and gibberellic acid (GA3) can be productive amendments. Both can potentially improve the plant's growth attributes and flowering, which are imperative in improving growth and yield. However, limited literature is available on their combined use in canola to mitigate salinity stress. That's why the current study investigates the impact of different levels of MJ (at concentrations of 0.8, 1.6, and 3.2 mM MJ) and GA3 (0GA3 and 5 mg/L GA3) on canola cultivated in salt-affected soils. Applying all the treatments in four replicates. Results indicate that the application of 0.8 mM MJ with 5 mg/L GA3 significantly enhances shoot length (23.29%), shoot dry weight (24.77%), number of leaves per plant (24.93%), number of flowering branches (26.11%), chlorophyll a (31.44%), chlorophyll b (20.28%) and total chlorophyll (27.66%) and shoot total soluble carbohydrates (22.53%) over control. Treatment with 0.8 mM MJ and 5 mg/L GA3 resulted in a decrease in shoot proline (48.17%), MDA (81.41%), SOD (50.59%), POD (14.81%) while increase in N (10.38%), P (15.22%), and K (8.05%) compared to control in canola under salinity stress. In conclusion, 0.8 mM MJ + 5 mg/L GA3 can improve canola growth under salinity stress. More investigations are recommended at the field level to declare 0.8 mM MJ + 5 mg/L GA3 as the best amendment for alleviating salinity stress in different crops.

Comparative proteomic and metabolomic analyses reveal stress responses of hemp to salinity.

KEY MESSAGE: Integrated omics analyses outline the cellular and metabolic events of hemp plants in response to salt stress and highlight several photosynthesis and energy metabolism related pathways as key regulatory points. Soil salinity affects many physiological processes of plants and leads to crop yield losses worldwide. For hemp, a crop that is valued for multiple aspects, such as its medical compounds, fibre, and seed, a comprehensive understanding of its salt stress responses is a prerequisite for resistance breeding and tailoring its agronomic performance to suit certain industrial applications. Here, we first observed the phenotype of salt-stressed hemp plants and found that under NaCl treatment, hemp plants displayed pronounced growth defects, as indicated by the significantly reduced average height, number of leaves, and chlorophyll content. Next, we conducted comparative proteomics and metabolomics to dissect the complex salt-stress response mechanisms. A total of 314 proteins and 649 metabolites were identified to be differentially behaving upon NaCl treatment. Functional classification and enrichment analysis unravelled that many differential proteins were proteases associated with photosynthesis. Through metabolic pathway enrichment, several energy-related pathways were found to be altered, such as the biosynthesis and degradation of branched-chain amino acids, and our network analysis showed that many ribosomal proteins were involved in these metabolic adaptations. Taken together, for hemp plants, influences on chloroplast function probably represent a major toxic effect of salinity, and modulating several energy-producing pathways possibly through translational regulation is presumably a key protective mechanism against the negative impacts. Our data and analyses provide insights into our understanding of hemp's stress biology and may lay a foundation for future functional genomics studies.

Phenotypical and biochemical characterization of tomato plants treated with triacontanol.

Biostimulants are heterogeneous products designed to support plant development and to improve the yield and quality of crops. Here, we focused on the effects of triacontanol, a promising biostimulant found in cuticle waxes, on tomato growth and productivity. We examined various phenological traits related to vegetative growth, flowering and fruit yield, the metabolic profile of fruits, and the response of triacontanol-treated plants to salt stress. Additionally, a proteomic analysis was conducted to clarify the molecular mechanisms underlying triacontanol action. Triacontanol application induced advanced and increased blooming without affecting plant growth. Biochemical analyses of fruits showed minimal changes in nutritional properties. The treatment also increased the germination rate of seeds by altering hormone homeostasis and reduced salt stress-induced damage. Proteomics analysis of leaves revealed that triacontanol increased the abundance of proteins related to development and abiotic stress, while down-regulating proteins involved in biotic stress resistance. The proteome of the fruits was not significantly affected by triacontanol, confirming that biostimulation did not alter the nutritional properties of fruits. Overall, our findings provide evidence of the effects of triacontanol on growth, development, and stress tolerance, shedding light on its mechanism of action and providing new insights into its potential in agricultural practices.

Zinc regulation of chlorophyll fluorescence and carbohydrate metabolism in saline-sodic stressed rice seedlings.

Saline-sodic stress can limit the absorption of available zinc in rice, subsequently impacting the normal photosynthesis and carbohydrate metabolism of rice plants. To investigate the impact of exogenous zinc application on photosynthesis and carbohydrate metabolism in rice grown in saline-sodic soil, this study simulated saline-sodic stress conditions using two rice varieties, 'Changbai 9' and 'Tonghe 899', as experimental materials. Rice seedlings at 4 weeks of age underwent various treatments including control (CT), 2 µmol·L-1 zinc treatment alone (Z), 50 mmol·L-1 saline-sodic treatment (S), and 50 mmol·L-1 saline-sodic treatment with 2 µmol·L-1 zinc (Z + S). We utilized JIP-test to analyze the variations in excitation fluorescence and MR820 signal in rice leaves resulting from zinc supplementation under saline-sodic stress, and examined the impact of zinc supplementation on carbohydrate metabolism in both rice leaves and roots under saline-sodic stress. Research shows that zinc increased the chloroplast pigment content, specific energy flow, quantum yield, and performance of active PSII reaction centers (PIABS), as well as the oxidation (VOX) and reduction rate (Vred) of PSI in rice leaves under saline-sodic stress. Additionally, it decreased the relative variable fluorescence (WK and VJ) and quantum energy dissipation yield (φDO) of the rice. Meanwhile, zinc application can reduce the content of soluble sugars and starch in rice leaves and increasing the starch content in the roots. Therefore, the addition of zinc promotes electron and energy transfer in the rice photosystem under saline-sodic stress. It enhances rice carbohydrate metabolism, improving the rice plants' ability to withstand saline-sodic stress and ultimately promoting rice growth and development.

A meta-analysis of photosynthetic efficiency and stress mitigation by melatonin in enhancing wheat tolerance.

BACKGROUND: Our meta-analysis examines the effects of melatonin on wheat under varying abiotic stress conditions, focusing on photosynthetic parameters, chlorophyll fluorescence, leaf water status, and photosynthetic pigments. We initially collected 177 publications addressing the impact of melatonin on wheat. After meticulous screening, 31 published studies were selected, encompassing 170 observations on photosynthetic parameters, 73 on chlorophyll fluorescence, 65 on leaf water status, 240 on photosynthetic pigments. RESULTS: The analysis revealed significant heterogeneity across studies (I² > 99.90%) for the aforementioned parameters and evidence of publication bias, emphasizing the complex interaction between melatonin application and plant physiological responses. Melatonin enhanced the overall response ratio (lnRR) for photosynthetic rates, stomatal conductance, transpiration rates, and fluorescence yields by 20.49, 22.39, 30.96, and 1.09%, respectively, compared to the control (no melatonin). The most notable effects were under controlled environmental conditions. Moreover, melatonin significantly improved leaf water content and reduced water potential, particularly under hydroponic conditions and varied abiotic stresses, highlighting its role in mitigating water stress. The analysis also revealed increases in chlorophyll pigments with soil drenching and foliar spray, and these were considered the effective application methods. Furthermore, melatonin influenced chlorophyll SPAD and intercellular CO2 concentrations, suggesting its capacity to optimize photosynthetic efficiency. CONCLUSIONS: This synthesis of meta-analysis confirms that melatonin significantly enhances wheat's resilience to abiotic stress by improving photosynthetic parameters, chlorophyll fluorescence, leaf water status, and photosynthetic pigments. Despite observed heterogeneity and publication bias, the consistent beneficial effects of melatonin, particularly under controlled conditions with specific application methods e.g. soil drenching and foliar spray, demonstrate its utility as a plant growth regulator for stress management. These findings encourage focused research and application strategies to maximize the benefits of melatonin in wheat farming, and thus contributing to sustainable agricultural practices.

Physiological, biochemical and transcriptomic insights into the mechanisms by which molybdenum mitigates cadmium toxicity in Triticum aestivum L.

There are many heavy metal stresses in agricultural biological systems, especially cadmium (Cd) stress, which prevent the full growth of plants, lead to a serious decline in crop yield, and endanger human health. Molybdenum (Mo), an essential nutrient element for plants, regulates plant growth mainly by reducing the absorption of heavy metals and protecting plants from oxidative damage. The aim of this study was to determine the protective effect of Mo (1 µM) application on wheat plants under conditions of Cd (10 µM) toxicity. The biomass, Cd and Mo contents, photosynthesis, leaf and root ultrastructure, antioxidant system, and active oxygen content of the wheat plants were determined. Mo increased the total chlorophyll content of wheat leaves by 43.02% and the net photosynthetic rate by 38.67%, and ameliorated the inhibitory effect of cadmium on photosynthesis by up-regulating photosynthesis-related genes and light-trapping genes. In addition, Mo reduced the content of superoxide anion (O2•-) by 16.55% and 31.12%, malondialdehyde (MDA) by 20.75% and 7.17%, hydrogen peroxide (H2O2) by 24.69% and 8.17%, and electrolyte leakage (EL) by 27.59% and 16.82% in wheat leaves and roots, respectively, and enhanced the antioxidant system to reduce the burst of reactive oxygen species and alleviate the damage of Cd stress on wheat. According to the above results, Mo is considered a plant essential nutrient that enhances Cd tolerance in wheat by limiting the absorption, accumulation and transport of Cd and by regulating antioxidant defence mechanisms. ENVIRONMENTAL IMPLICATION: Cadmium (Cd)，is one of the most toxic heavy metals in the environment, and Cd pollution is a global environmental problem that threatens food security and human health. Molybdenum (Mo), as an essential plant nutrient, is often used to resist environmental stress. However, the mechanism of Mo treatment on wheat subjected to Cd stress has not been reported. In this study, we systematically analysed the effects of Mo on the phenotype, physiology, biochemistry, ultrastructure and Cd content of wheat subjected to Cd stress, and comprehensively analysed the transcriptomics. It not only reveals the mechanism of Mo tolerance to Cd stress in wheat, but also provides new insights into phytoremediation and plant growth in Cd-contaminated soil.

NMR and LC-MS-based metabolomics to investigate the efficacy of a commercial bio stimulant for the treatment of wheat (Triticum aestivum).

INTRODUCTION: Bio stimulants are substances and/or microorganisms that are used to improve plant growth and crop yields by modulating physiological processes and metabolism of plants. While research has primarily focused on the broad effects of bio stimulants in crops, understanding their cellular and molecular influences in plants, using metabolomic analysis, could elucidate their effectiveness and offer possibilities for fine-tuning their application. One such bio stimulant containing galacturonic acid as elicitor is used in agriculture to improve wheat vigor and strengthen resistance to lodging. OBJECTIVE: However, whether a metabolic response is evolved by plants treated with this bio stimulant and the manner in which the latter might regulate plant metabolism have not been studied. METHOD: Therefore, the present study used 1H-NMR and LC-MS to assess changes in primary and secondary metabolites in the roots, stems, and leaves of wheat (Triticum aestivum) treated with the bio stimulant. Orthogonal partial least squares discriminant analysis effectively distinguished between treated and control samples, confirming a metabolic response to treatment in the roots, stems, and leaves of wheat. RESULTS: Fold-change analysis indicated that treatment with the bio stimulation solution appeared to increase the levels of hydroxycinnamic acid amides, lignin, and flavonoid metabolism in different plant parts, potentially promoting root growth, implantation, and developmental cell wall maturation and lignification. CONCLUSION: These results demonstrate how non-targeted metabolomic approaches can be utilized to investigate and monitor the effects of new agroecological solutions based on systemic responses.

Repairing Host Damage Caused by Tobacco Mosaic Virus Stress: Design, Synthesis, and Mechanism Study of Novel Oxadiazole and Arylhydrazone Derivatives.

Tobacco mosaic virus (TMV), as one of the most traditional and extensive biological stresses, poses a serious threat to plant growth and development. In this work, a series of 1-phenyl/tertbutyl-5-amino-4-pyrazole oxadiazole and arylhydrazone derivatives was synthesized. Bioassay evaluation demonstrated that the title compounds (P1-P18) without a "thioether bond" lost their anti-TMV activity, while some of the ring-opening arylhydrazone compounds exhibited superior in vivo activity against TMV in tobacco. The EC50 value of title compound T8 for curative activity was 139 µg/mL, similar to that of ningnanmycin (NNM) (EC50 = 152 µg/mL). Safety analysis revealed that compound T8 had no adverse effects on plant growth or seed germination at a concentration of 250 µg/mL. Morphological observation revealed that compound T8 could restore the leaf tissue of a TMV-stressed host and the leaf stomatal aperture to normal. A mechanism study further revealed that compound T8 not only restored the photosynthetic and growth ability of the damaged host to normal levels but also enhanced catalase (CAT) activity and reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in the damaged host, thereby reducing the oxidation damage to the host. TMV-green fluorescent protein (GFP) experiments further demonstrated that compound T8 not only slowed the transmission speed of TMV in the host but also inhibited its reproduction. All of the experimental results demonstrated that compound T8 could reduce the oxidative damage caused by TMV stress and regulate the photosynthetic ability of the host, achieving the ability to repair damage, to make the plant grow normally.

Physicochemical properties and fractal characterizations of the functionalized porous clinoptilolites for controlling alginate delivery in growing cauliflower and leaf mustard.

Using natural clinoptilolite (NCP) as a carrier and alginate (Alg)-calcium as an active species, the porous silicon calcium alginate nanocomposite (Alg-Ca-NCP) was successfully fabricated via adsorption-covalence-hydrogen bond. Its structural features and physicochemical properties were detailed investigated by various characterizations. The results indicated that Alg-Ca-NCP presented the disordered lamellar structures with approximately uniform particles in size of 300-500 nm. Specially, their surface fractal evolutions between the irregular roughness and dense structures were demonstrated via the SAXS patterns. The results elucidated that the abundant micropores of NCP were beneficial for unrestricted diffusing of Alg-Ca, which was conducive to facilitate a higher loading and sustainable releasing. The Ca content of leaf mustard treated with Alg-Ca-NCP-0.5 was 484.5 mg/100g on the 21st day, higher than that by water (CK) and CaCl2 solution treatments, respectively. Meanwhile, the prepared Alg-Ca-NCPs presented the obvious anti-aging effects on peroxidase drought stress of mustard leaves. These demonstrations provided a simple and effective method to synthesize Alg-Ca-NCPs as delivery nanocomposites, which is useful to improve the weak absorption and low utilization of calcium alginate by plants.

Exogenous curcumin mitigates As stress in spinach plants: A biochemical and metabolomics investigation.

The spinach (S. oleracea L.) was used as a model plant to investigate As toxicity on physio-biochemical processes, exploring the potential mitigation effect of curcumin (Cur) applied exogenously at three concentrations (1, 10, and 20 µM Cur). The employment of Cur significantly mitigated As-induced stress in spinach photosynthetic performance (Fv/Fm, Fo/Fm, and Fv/Fo). Moreover, the co-incubation of Cur with As improved physiological processes mainly associated with plant water systems affected by As stress by recovering the leaf's relative water content (RWC) and osmotic potential (ψπ) nearly to the control level and increasing the transpiration rate (E; 39-59%), stomatal conductivity (gs; 86-116%), and carbon assimilation rate (A; 84-121%) compared to As stressed plants. The beneficial effect of Cur in coping with As-induced stress was also assessed at the plant's oxidative level by reducing oxidative stress biomarkers (H2O2 and MDA) and increasing non-enzymatic antioxidant capacity. Untargeted metabolomics analysis was adopted to investigate the main processes affected by As and Cur application. A multifactorial ANOVA discrimination model (AMOPLS-DA) and canonical correlation analysis (rCCA) were employed to identify relevant metabolic changes and biomarkers associated with Cur and As treatments. The results highlighted that Cur significantly determined the accumulation of glucosinolates, phenolic compounds, and an increase in glutathione redox cycle activities, suggesting an overall elicitation of plant secondary metabolisms. Specifically, the correlation analysis reported a strong and positive correlation between (+)-dihydrokaempferol, L-phenylalanine (precursor of phenolic compounds), and serotonin-related metabolites with antioxidant activities (ABTS and DPPH), suggesting the involvement of Cur application in promoting a cross-talk between ROS signaling and phytohormones, especially melatonin and serotonin, working coordinately to alleviate As-induced oxidative stress. The modulation of plant metabolism was also observed at the level of amino acids, fatty acids, and secondary metabolites synthesis, including N-containing compounds, terpenes, and phenylpropanoids to cooperate with As-induced stress response.

Physiological response and molecular mechanism of Quercus variabilis under cadmium stress.

Heavy metal pollution is a global environmental problem, and Quercus variabilis has a stronger tolerance to Cd stress than do other species. We aimed to explore the physiological response and molecular mechanisms of Q. variabilis to Cd stress. In this study, the antioxidant enzyme activities of leaves were determined, while the photosynthetic parameters of leaves were measured using Handy PEA, and ion fluxes and DEGs in the roots were investigated using noninvasive microtest technology (NMT) and RNA sequencing techniques, respectively. Cd stress at different concentrations and for different durations affected the uptake patterns of Cd2+ and H+ by Q. variabilis and affected the photosynthetic efficiency of leaves. Moreover, there was a positive relationship between antioxidant enzyme (CAT and POD) activity and Cd concentration. Transcriptome analysis revealed that many genes, including genes related to the cell wall, glutathione metabolism, ion uptake and transport, were significantly upregulated in response to cadmium stress in Q. variabilis roots. WGCNA showed that these DEGs could be divided into eight modules. The turquoise and blue modules exhibited the strongest correlations, and the most significantly enriched pathways were the phytohormone signaling pathway and the phenylpropanoid biosynthesis pathway, respectively. These findings suggest that Q. variabilis can bolster plant tolerance by modulating signal transduction and increasing the synthesis of compounds, such as lignin, under Cd stress. In summary, Q. variabilis can adapt to Cd stress by increasing the activity of antioxidant enzymes, and regulating the fluxes of Cd2+ and H+ ions and the expression of Cd stress-related genes.

Post-synthetic modification of nano-chitosan using gibberellic acid: Foliar application on sorghum under salt stress conditions and estimation of biochemical parameters.

The challenge of desert farming with a high salt level has become an ecological task due to salt stress negatively affecting plant growth and reproduction. The current study deals with the cultivation of sorghum under salt stress conditions to counteract the effect of chitosan and gibberellic acid (GA3). Here, the effects of chitosan, GA3 and nano-composite (GA3@chitosan) on biochemical contents, growth and seed yield of sorghum under salinity stress conditions were studied. The results showed that spraying with GA3@chitosan increased sorghum grain yield by 2.07, 1.81 and 1.64 fold higher than salinity stressed plants, chitosan treatment and GA3 treatment, respectively. Additionally, compared to the control of the same variety, the GA3@chitosan spraying treatment improved the concentration of microelements in the grains of the Shandweel-1 and Dorado by 24.51% and 18.39%, respectively for each variety. Furthermore, spraying GA3@chitosan on sorghum varieties increased the accumulation of the macroelements N, P, and K by 34.03%, 47.61%, and 8.67% higher than salt-stressed plants, respectively. On the other hand, the proline and glycinebetaine content in sorghum leaves sprayed with nano-composite were drop by 51.04% and 11.98% less than stressed plants, respectively. The results showed that, in Ras Sudr, the Shandweel-1 variety produced more grain per feddan than the Dorado variety. These findings suggest that GA3@chitosan improves the chemical and biochemical components leading to a decrease in the negative effect of salt stress on the plant which reflects in the high-yield production of cultivated sorghum plants in salt conditions.

Impact of exogenous melatonin foliar application on physiology and fruit quality of wine grapes (Vitis vinifera) under salt stress.

Soil salinisation is an important abiotic stress faced in grape cultivating, leading to weakened plant vigour and reduced fruit quality. Melatonin as a novel hormone has shown positive exogenous application value. Therefore, this study used wine grape (Vitis vinifera ) 'Pinot Noir' as a test material to investigate the changes of foliar spraying with different concentrations of melatonin on the physiology and fruit quality of wine grapes in a field under simulated salt stress (200mmolL-1 NaCl). The results showed that foliar spraying of melatonin significantly increased the intercellular CO2 concentration, maximum photochemical quantum yield of PSII, relative chlorophyll and ascorbic acid content of the leaves, as well as the single spike weight, 100-grain weight, transverse and longitudinal diameters, malic acid, α-amino nitrogen and ammonia content of fruits, and decreased the initial fluorescence value of leaves, ascorbate peroxidase activity, glutathione content, fruit transverse to longitudinal ratio and tartaric acid content of plants under salt stress. Results of the comprehensive evaluation of the affiliation function indicated that 100µmolL-1 melatonin treatment had the best effect on reducing salt stress in grapes. In summary, melatonin application could enhance the salt tolerance of grapes by improving the photosynthetic capacity of grape plants under salt stress and promoting fruit development and quality formation, and these results provide new insights into the involvement of melatonin in the improvement of salt tolerance in crop, as well as some theoretical basis for the development and industrialisation of stress-resistant cultivation techniques for wine grapes.

Evaluation of potential increase in photosynthetic efficiency of cassava (Manihot esculenta Crantz) plants exposed to elevated carbon dioxide.

Cassava (Manihot esculenta Crantz), an important tropical crop, is affected by extreme climatic events, including rising CO2 levels. We evaluated the short-term effect of elevated CO2 concentration (ECO2 ) (600, 800 and 1000ppm) on the photosynthetic efficiency of 14 cassava genotypes. ECO2 significantly altered gaseous exchange parameters (net photosynthetic rate (P n ), stomatal conductance (g s ), intercellular CO2 (C i ) and transpiration (E )) in cassava leaves. There were significant but varying interactive effects between ECO2 and varieties on these physiological characteristics. ECO2 at 600 and 800ppm increased the P n rate in the range of 13-24% in comparison to 400ppm (ambient CO2 ), followed by acclimation at the highest concentration of 1000ppm. A similar trend was observed in g s and E . Conversely, C i increased significantly and linearly across increasing CO2 concentration. Along with C i , a steady increase in water use efficiency [WUEintrinsic (P n /g s ) and WUEinstantaneous (P n /E )] across various CO2 concentrations corresponded with the central role of restricted stomatal activity, a common response under ECO2 . Furthermore, P n had a significant quadratic relationship with the ECO2 (R 2 =0.489) and a significant and linear relationship with C i (R 2 =0.227). Relative humidity and vapour pressure deficit during the time of measurements remained at 70-85% and ~0.9-1.31kPa, respectively, at 26±2°C leaf temperature. Notably, not a single variety exhibited constant performance for any of the parameters across CO2 concentrations. Our results indicate that the potential photosynthesis can be increased up to 800ppm cassava varieties with high sink capacity can be cultivated under protected cultivation to attain higher productivity.

Investigating the growth promotion potential of biochar on pea (Pisum sativum) plants under saline conditions.

Pea, member of the plant family Leguminosae, play a pivotal role in global food security as essential legumes. However, their production faces challenges stemming from the detrimental impacts of abiotic stressors, leading to a concerning decline in output. Salinity stress is one of the major factors that limiting the growth and productivity of pea. However, biochar amendment in soil has a potential role in alleviating the oxidative damage caused by salinity stress. The purpose of the study was to evaluate the potential role of biochar amendment in soil that may mitigate the adverse effect of salinity stress on pea. The treatments of this study were, (a) Pea varieties; (i) V1 = Meteor and V2 = Green Grass, Salinity Stress, (b) Control (0 mM) and (ii) Salinity (80 mM) (c) Biochar applications; (i) Control, (ii) 8 g/kg soil (56 g) and (iii) 16 g/kg soil (112 g). Salinity stress demonstrated a considerable reduction in morphological parameters as Shoot and root length decreased by (29% and 47%), fresh weight and dry weight of shoot and root by (85, 63%) and (49, 68%), as well as area of leaf reduced by (71%) among both varieties. Photosynthetic pigments (chlorophyll a, b, and carotenoid contents decreased under 80 mM salinity up to (41, 63, 55 and 76%) in both varieties as compared to control. Exposure of pea plants to salinity stress increased the oxidative damage by enhancing hydrogen peroxide and malondialdehyde content by (79 and 89%), while amendment of biochar reduced their activities as, (56% and 59%) in both varieties. The activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) were increased by biochar applications under salinity stress as, (49, 59, and 86%) as well as non-enzymatic antioxidants as, anthocyanin and flavonoids improved by (112 and 67%). Organic osmolytes such as total soluble proteins, sugars, and glycine betaine were increased up to (57, 83, and 140%) by biochar amendment. Among uptake of mineral ions, shoot and root Na+ uptake was greater (144 and 73%) in saline-stressed plants as compared to control, while shoot and root Ca2+ and K+ were greater up to (175, 119%) and (77, 146%) in biochar-treated plants. Overall findings revealed that 16 g/kg soil (112 g) biochar was found to be effective in reducing salinity toxicity by causing reduction in reactive oxygen species and root and shoot Na+ ions uptake and improving growth, physiological and anti-oxidative activities in pea plants (Fig. 1). Figure 1 A schematic diagram represents two different mechanisms of pea under salinity stress (control and 80 mM NaCl) with Biochar (8 and 16 g/kg soil).