Plants' Physio-Biochemical and Phyto-Hormonal Responses to Alleviate the Adverse Effects of Drought Stress: A Comprehensive Review

Phosphogypsum improves soil and benefits crop growth: An effective measure for utilizing solid waste resources

The utilization rate of phosphogypsum (PG) is currently low, and prolonged storage poses environmental pollution. Therefore, there is an urgent need to promote resource-efficient utilization. This study investigated the alterations in the characteristics of modified PG artificial soil (MPG-soil) and their influence on buckwheat (Fagopyrum esculentum Moench) growth using hierarchical land reclamation technique (HLRT) and integrated land reclamation technique (ILRT). The results demonstrated that MPG-soil reduced bulk density (3.8-6.9%), enhanced moisture content (up to 22%), and improved enzymatic activity. HLRT achieved superior phosphorus mineralization (7.53 U/g S-NP activity) and increased buckwheat yield by 130.6% over controls. Despite elevated soil salinity, MPG amendments restricted heavy metal accumulation in grains (BCF < 0.3), though Pb levels exceeded national standards due to background contamination. Nutrient dynamics revealed increased phosphorus availability but reduced organic matter, necessitating supplemental fertilization. The Nemerow index confirmed all treatments as "Safe and Clean", while principal component analysis highlighted HLRT's efficacy in balancing soil structure and fertility. Proline accumulation in high-PG treatments indicated adaptive stress responses. MPG-soil effectively contained heavy metal migration, ensuring agricultural product safety. This study assessed the potential of PG for land reclamation, and provided guidelines for its safe utilization in agriculture.

Role of plant growth-promoting rhizobacteria in sustainable agriculture: Addressing environmental and biological challenges

This review underscores the importance of plant growth-promoting rhizobacteria (PGPR), fostering sustainability to address various environmental and biological issues. PGPR helps crops withstand salinity, nutrient deficiencies, and drought stress while tackling agricultural threats. Sustainable agriculture has emerged as a response to the social and economic problems farming practices face. Plants encounter obstacles from biotic stressors such as bacteria, viruses, nematodes, arachnids, and weeds that impede their growth. Furthermore, PGPR enhances plant growth through improved nutrient absorption and defense against pests. Bacillus subtilis utilizes indirect methods to combat diseases and protect plants from various diseases and pests. Additionally, PGPR acts as a bio-fertilizer that mitigates drought stress effects on crops in various regions worldwide. This review proposes strategies to boost productivity and improve bio-inoculant efficiency under real-world conditions. PGPR demonstrates its role in combating threats by influencing plant defense mechanisms, initiating systemic resistance responses, and regulating gene expression related to pathogen detection and defense signaling pathways. It maintains a balanced root microbiome by suppressing harmful microbial proliferation while promoting beneficial microbial interactions. Despite the challenges posed by technology and ethical considerations surrounding their modification, integrating PGPR into farming methods holds promise for sustainable agriculture. Given the increasing impact of climate change, PGPR plays a crucial role in improving crop resilience, enhancing soil quality, and reducing dependence on synthetic agricultural inputs.

The potential of seaweed-derived polysaccharides as sustainable biostimulants in agriculture

Seaweed polysaccharides such as alginate, carrageenan, agar, and ulvan are emerging as key bioresources in sustainable agriculture due to their unique structural characteristics and functional properties. This review highlights their potential as eco-friendly biostimulants capable of enhancing soil health, plant growth, and stress resilience. Specific mechanisms, including the gel-forming capacity of alginate, ion exchange abilities, and the hydrophilic nature of these polysaccharides, enable improved water retention, nutrient uptake, and plant productivity under adverse conditions, including drought, salinity, and extreme temperatures. Moreover, their role as hydrogels and bio-elicitors introduces novel approaches to addressing global challenges in agriculture, such as climate change and food security. Real-world applications, such as the use of Ascophyllum nodosum extract for drought tolerance and Gracilaria tenuistipitata var. liui to boost grain yields, underscore the practicality and success of these biostimulants. Despite their promising applications, challenges like variability in seaweed quality, high extraction costs, and limited product standardization hinder their scalability. This review provides an integrated analysis of their biochemical properties, agricultural applications, and commercial products while proposing solutions to optimize their use for advancing sustainable farming practices.

The regulatory role of phytohormones in plant drought tolerance

MAIN CONCLUSION

This paper highlights the role of various signaling hormones in drought stress tolerance. It explains how phytohormones act and interact under drought conditions. Drought stress significantly impairs plant growth, development and productivity. The likelihood of adverse impacts of drought will increase due to variations in global climate patterns. Phytohormones serve as key regulators of drought tolerance mechanisms in plants. The in-depth understanding of the role and signaling of such hormones is thus of great significance for plant stress management. In this review, we conducted a bibliometric analysis and thematic mapping of recent research on drought and phytohormones, and phytohormone interactions. It is assumed that different classes of phytohormones such as abscisic acid (ABA), auxins (IAA), cytokinins (CTK), ethylene (ETH), gibberellic acid (GA), brassinosteroids (BRs), salicylates (SA), jasmonates (JA), and strigolactones (SLs) play a pivotal role in drought resistance mechanisms in many crops. The present work highlights recent advances in plant responses to drought and uncovers the recent functions of phytohormones in the establishment of drought-specific tolerance strategies. It also deciphers the various interactions between phytohormones allowing plant adaptation to drought stress. Overall, this review highlights recent and original discoveries useful for developing new strategies to improve plant resistance to drought.

Biochemical and gene expression profiling of five pear species under drought stress conditions

Drought is one of the crucial abiotic stresses which affects growth, development, and performance of pear trees. This research was performed to investigate responses of five pear species including Pyrus communis L., Pyrus boissieriana Bushe., Pyrus glabra Boiss., Pyrus syriaca Boiss., and Pyrus salicifolia Pall. to different levels of drought stress. The potted trees were irrigated with water volume of 100%, 60%, or 30% of field capacity (FC) during 90 days. Based on the visual observation, the plant growth was restricted by severe drought in all species. Malondialdehyde (MDA) and glycine betaine (GB) contents, as well as the ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) activities were indicated an uprising behavior under drought stress. Principal component analysis (PCA) analysis revealed P. glabra as tolerant and P. communis as sensitive to drought stress. The expression rates of stress-responsive transcription factors (TFs); WRKY29 and DREB6 and their responding genes, including LEA29 and Dehydrin1, were analyzed in the two differentially drought-responding pear species i.e., P. glabra and P. communis. The expression of the studied TFs was induced when both species were exposed to higher drought levels. The species P. glabra exhibited better osmoregulation, antioxidant response, and higher up-regulation of WRKY29, DREB6, LEA29 and Dehydrin1. In conclusion, among the studied pear species, P. glabra could best tolerate drought stress by boosting protective mechanisms.

Integrated metabolomics, transcriptomic, and phytohormonal analyses to study the effects of water stress and foliar abscisic acid application in Thymus species using LC-MS/MS

Thyme species, including Thymus vulgaris, T. kotschyanus (drought-tolerant) and T. serpyllum (drought-sensitive), are valuable medicinal herbs. They are often grown in arid regions and are increasingly suffering from water stress due to climate change. Here, we analyzed the metabolome and expression of selected genes in leaves of these species under drought stress with and without treatment with the phytohormone abscisic acid (ABA). Among the terpenes, dominant metabolites in thyme, thymol was the most important terpenoid component, followed by thymoquinone, carvacrol and p-cymene in all three species. Drought stress reduced terpene concentrations, while moderate ABA levels increased them. T. kotschyanus showed the highest concentrations of thymol and carvacrol after combined treatment with drought and ABA. Metabolite accumulation was partially correlated with genes related to terpenoid biosynthesis. The combined treatment of drought stress and ABA resulted in a significant reduction of the stress hormone jasmonic acid and an increase of its biosynthetic precursor, OPDA (cis-12-oxophytodienoic acid), in all species. The present research results indicate that ABA treatment at moderate concentrations could be used as a measure to increase the production of some pharmaceutically active phenolic monoterpenes in T. vulgaris, T. serpyllum and T. kotschyanus and increase the stress resistance of the plants.

Comparative evaluation of bio-fertilizer replacement with chemical fertilizer in sesame (Sesamum indicum L) production under drought stress and normal irrigation condition

Drought stress represents a considerable environmental challenge, exerting a deleterious effect on plant growth and productivity. In order to address this issue, the use of biostimulants, such as plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF), has gained increasing attention in recent years. The present study, conducted in 2022, sought to evaluate the effects of biological and chemical fertilizers under drought-stress conditions on sesame yield and water-use efficiency. The research was conducted at two farms, Dashthouz and Sarkahnan, which are located approximately 80 km apart in Rodan city, Hormozgan province, Iran. The research was designed as a factorial experiment using a randomized complete block design (RCBD) with three replications. The study examined two main factors: fertilizer application, with eight levels (bacteria (B), mycorrhizal fungi (MY), chemical fertilizer (NPK), bacteria + mycorrhizal fungi (B+MY), bacteria + chemical fertilizer (B+NPK), mycorrhizal fungi + chemical fertilizer (MY+NPK), bacteria + mycorrhizal fungi + chemical fertilizer (B+MY+NPK), and a control), and drought stress, with two levels (normal irrigation without drought stress and drought stress). The results indicated that the main effects of location, irrigation, fertilizer application, and their interactions significantly influenced the leaf area index (LAI), number of branches, number of capsules, number of seeds per capsule, seed yield, biological yield, harvest index, oil yield, meal yield, and water-use efficiency. However, there was no significant effect on thousand-seed weight. This indicates that all measured traits were influenced by the experimental factors. Regarding seed yield, the lowest value of 95.3 g/m2 was recorded in the control treatment under normal irrigation conditions at Dachthouz, while the highest value of 325.5 g/m2 was achieved in the control treatment under normal irrigation conditions at Sarkahnan. The findings revealed that the application of mycorrhizal fungi (MY) and bacteria (B) as substitutes for phosphorus and nitrogen, respectively, produced seed yields comparable to those achieved with NPK fertilizers under normal irrigation conditions. However, under drought stress conditions, water scarcity disrupted the symbiotic interactions between the microorganisms and the crop, reducing the effectiveness of MY and B treatments in enhancing crop growth and yield. These results contribute to advancing sustainable sesame production systems by minimizing the reliance on chemical fertilizers and enhancing crop resilience to drought stress. Further research and practical implementation of these strategies could lead to more efficient and environmentally sustainable sesame cultivation practices.

Comprehensive Genomic Analysis of Trihelix Transcription Factor Genes and Their Expression Underlying Abiotic Stress in Euphrates Poplar (Populus euphratica)

Trihelix transcription factors (TTFs) are light-sensitive proteins characterized by a triple-helix structure that play a crucial role in regulating plant growth and development, especially in response to abiotic stressors, such as drought and salinity. This intriguing family of proteins has been the focus of extensive functional studies across various plant species. Despite their recognized significance, the trihelix family in Populus euphratica has not been thoroughly explored, warranting more attention. This study identifies 35 full-length trihelix genes in Populus euphratica, which are grouped into five categories (GT-1, GT-γ, GT-2, SIP1, and SH4) based on their conserved motifs and structural similarities, and these genes are unevenly distributed across 19 linkage groups on the chromosomes. A syntenic analysis was conducted in P. euphratica, comparing it to various other species. The promoters of P. euphratica contain numerous stress-responsive cis-elements, indicating the potential for these trihelix genes to respond to abiotic stress. RT-qPCR analysis discovered significant induction of the trihelix gene family in response to drought and salt stress, with 21 PeuTTF genes exhibiting distinct expression levels under drought conditions and five PeuTTF genes responsive to salt stress. Notably, heightened expression of PeuTTF6, PeuTTF9, and PeuTTF20 was observed in both roots and leaves during drought stress, suggesting that TTF expression is connected to the plant's response to such conditions. Additionally, significant increases in expression were noted for PeuTTF2, PeuTTF31, and PeuTTF32, which may be convoluted in the response to salt stress. These discoveries highlight the role that PeuTTF genes play in improving drought tolerance in P. euphratica plants. We offer new perspectives on the evolutionary trends and variants of PeuTTF genes in P. euphratica, and we establish the groundwork for understanding the functional properties of PeuTTF genes under salt-stressed and drought-stressed conditions. This study provides opportunities for the advancement of desert poplar agriculture and may have wider ramifications for tree plant breeding techniques targeted at improving tree performance and durability, particularly in dry areas.

Thymbra spicata extract and arbuscular mycorrhizae improved the morphophysiological traits, biochemical properties, and essential oil content and composition of Rosemary (Rosmarinus officinalis L.) under salinity stress

BACKGROUND

Enhancing the content of essential oils and valuable secondary metabolites is a primary goal for medicinal plant breeders. In this study, the effects of Thymbra spicata extract at concentrations of 0% (C), 10% (TS1), and 20% (TS2), along with mycorrhizal fungus (MF) biofertilizer at a rate of 50 g/2.5 kg of soil, were evaluated on the growth, photosynthetic pigments, relative water content (RWC), proline, protein, malondialdehyde (MDA), catalase (CAT), phenylalanine ammonia-lyase (PAL), and essential oil content and composition of Rosmarinus officinalis L. under varying salinity stress levels of 0 mM (S0), 100 mM (S1), and 200 mM (S2) NaCl. The experiment was conducted as a factorial study within a completely randomized design, with three replications.

RESULTS

As salinity stress increased, the yield and growth characteristics of the plants declined. However, the applied treatments effectively mitigated the negative effects of salinity. The highest chlorophyll a, b, and total chlorophyll contents were observed in the TS2 + MF treatment under nonsaline conditions. Under S2 salinity stress, carotenoid and anthocyanin contents increased by 38.29% and 11.11%, respectively, with the use of TS2 + MF. Under S1 stress conditions, the proline and soluble sugar content increased by 268% and 44%, respectively, in the MF treatment. Essential oil content was enhanced by 80.43% with the TS2 + MF treatment under S1 stress. Essential oil analysis showed significant increases in camphene (9.71%), β-pinene (43.75%), α-phellandrene (13.3%), geranyl acetate (156%), cineole (21.39%), and β-linalool (5.12%) in the TS2 + MF treatment compared to the control under S1 stress conditions.

CONCLUSIONS

Among all the treatments, the combined application of TS2 and MF proved to be the most effective in enhancing the morphophysiological and biochemical characteristics of rosemary plants. This treatment not only boosted the production of essential oils and secondary metabolites but also mitigated the detrimental effects of salinity stress. Therefore, it is recommended as a beneficial agricultural practice for improving the productivity and quality of rosemary plants under salinity stress.

Impacts of pseudomonas fluorescent bacterial fertilizer addition on the soil environment and fruit yield under water stress in greenhouse grape

Bacterial fertilizers, which contain beneficial soil microorganisms, are becoming more widely used as they can mitigate the problems of crop yields reduction and soil environment degradation caused by the overuse of chemical fertilizer. However, the impact of bacterial fertilizer on greenhouse grape yields and the rhizosphere soil environment has not been assessed in arid and semi-arid region of Northwest China. Thus, a 2-year field trial was conducted with five treatments: adequate water supply without bacterial fertilizer (CK); mild (W1), moderate (W2) water stress and small (F1), maximize (F2) fertilizer cross-combination, respectively. The results indicated that water stress had a negative impact on the accumulation of dissolved organic carbon (DOC), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) in the rhizosphere soil. The addition of pseudomonas fluorescent bacterial fertilizer significantly increased the content of available phosphorus (AP), DOC, MBC and MBN content. The W1F2 treatment significantly increased the activities of urease, catalase and sucrase (p < 0.05). The W1F1 and W1F2 treatments increased fungal and bacterial diversity. Bacterial community composition was closely related to soil total organic carbon (TOC), soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), MBC, and sucrase, while fungi community composition was significantly related to Nitrate-N (NO3 --N), TN, and sucrase. Additionally, compared with CK treatment the yield and economic benefit of the W1F2 treatment increased by 35.44 and 44.04%, respectively. Therefore, W1F2 is recommended as the optimal water and fertilizer management scheme for efficient greenhouse grape production in the arid and semi-arid region of Northwest China.

MicroRNAs in Plant Genetic Regulation of Drought Tolerance and Their Function in Enhancing Stress Adaptation

Adverse environmental conditions, including drought stress, pose a significant threat to plant survival and agricultural productivity, necessitating innovative and efficient approaches to enhance their resilience. MicroRNAs (miRNAs) are recognized as key elements in regulating plant adaptation to drought stress, with a notable ability to modulate various physiological and molecular mechanisms. This review provides an in-depth analysis of the role of miRNAs in drought response mechanisms, including abscisic acid (ABA) signaling, reactive oxygen species (ROS) detoxification, and the optimization of root system architecture. Additionally, it examines the effectiveness of bioinformatics tools, such as those employed in in silico analyses, for studying miRNA-mRNA interactions, as well as the potential for their integration with experimental methods. Advanced methods such as microarray analysis, high-throughput sequencing (HTS), and RACE-PCR are discussed for their contributions to miRNA target identification and validation. Moreover, new data and perspectives are presented on the role of miRNAs in plant responses to abiotic stresses, particularly drought adaptation. This review aims to deepen the understanding of genetic regulatory mechanisms in plants and to establish a robust scientific foundation for the development of drought-tolerant crop varieties.

Bacillus velezensis S141 improves the root growth of soybean under drought conditions

Bacillus velezensis S141 helps soybean establish specific symbiosis with strains of Bradyrhizobium diazoefficiens to form larger nodules and improve nitrogen fixation efficiency. In this study, we found that the dry weight of soybean roots increased significantly in the presence of S141 alone under drought conditions. Hence, S141 improved the root growth of soybean under limited water supply conditions. S141 can produce some auxin, which might be involved in the improved nodulation. Inactivating IPyAD of S141, which is required for auxin biosynthesis, did not alter the beneficial effects of S141, suggesting that the root growth was independent of auxin produced by S141. Under drought conditions, soybean exhibited some responses to resist osmotic and oxidative stresses; however, S141 was relevant to none of these responses. Although the mechanism remains unclear, S141 might produce some substances that stimulate the root growth of soybean under drought conditions.

Interplay Between Phytohormones and Sugar Metabolism in Dendrocalamus latiflorus

Dendrocalamus latiflorus, a species of giant bamboo, holds significant ecological and economic value. This review delves into the intricate interplay between phytohormones and sugar metabolism in Dendrocalamus latiflorus, emphasizing species-specific mechanisms that enhance its ecological adaptability and rapid growth. By synthesizing recent research, this work highlights how phytohormones, including auxins, cytokinins, and abscisic acid, regulate sugar metabolism pathways such as glycolysis and starch degradation in response to environmental stimuli. These hormones influence crucial plant processes, including cell division, elongation, stress responses, and sugar metabolism pathways such as glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation. Geographic variations in these processes are examined, demonstrating their role in environmental adaptation and ecological resilience. For instance, populations in nutrient-rich soils exhibit enhanced cytokinin activity and sugar transport efficiency, while those in water-limited areas display elevated abscisic acid levels, aiding drought tolerance. This targeted focus on D. latiflorus provides novel insights into its potential applications in sustainable forestry and agroforestry systems. By integrating recent advances, this review highlights the critical role of phytohormone-sugar interplay in improving the productivity and stress resilience of D. latiflorus, with implications for agroforestry systems and climate change adaptation.

Melatonin induces drought stress tolerance by regulating the physiological mechanisms, antioxidant enzymes, and leaf structural modifications in Rosa centifolia L

Melatonin is considered an effective bio-stimulant that is crucial in managing several abiotic stresses including drought. However, its potential mechanisms against drought stress in fragrant roses are not well understood. Here, we aim to investigate the role of melatonin on Rosa centifolia plants cultivated under drought stress (40 % field capacity) and normal irrigation (80 % field capacity). Plant growth traits, gaseous exchange, antioxidants, osmolytes, oxidative stress, and leaf anatomical attributes were measured. All pots were arranged with a completely randomized design with two-factor factorial setup. Foliar application of melatonin was carried out on the next day of drought treatment and was repeated weekly, while normal watering was regarded as control. Drought stress significantly enhanced oxidative stress markers and reduced growth parameters in water-deficit rose plants. However, melatonin spray (100 μM) produced increased plant height (16 %), flower yield (16 %), petal fresh and dry biomass (7 % and 38 %), total chlorophyll (48 %), contents of carotenoid (54 %), and gaseous exchange traits such as stomatal conductance (25 %), photosynthetic rate (91 %), and transpiration rate (3 %), in water-deficient plants. Likewise, the accretion of catalase, superoxide dismutase, soluble protein, proline, and glycine betaine contents was recorded by 22 %, 45 %, 58 %, 7 %, and 6 %, respectively, in drought-stressed plants, due to melatonin treatment. Increment of oxidative stress indicators i.e. malondialdehyde (-37 %) and hydrogen peroxide (-27 %) was diminished by melatonin triggered by drought stress. Furthermore, leaf cortex (51 %), vascular bundle area (76 %), palisade cell area (59 %), and lamina thickness (42 %) were remarkably increased with melatonin foliar sprays in water-deficit plants. The results of this study recommend that melatonin is a protective agent against drought stress and has potential application prospects in the rose-producing regions suffering from water deficiency. Future studies should focus on molecular responses of R. centifolia to drought stress to further develop stress alleviation strategies in floricultural crops.

Alleviation of drought stress in tomato by foliar application of seafood waste extract

To manage the adverse effects of garbage pollution and avoid using chemicals, a natural extract of seafood shells was obtained and explored for its beneficial role. Physical characterization highlighted that its active compounds correspond to chitin and its derivative, chitosan. The ability of the extracted biostimulant to foster tomato tolerance was tested on drought-stressed plants. Along with changes in morphological parameters, the accumulation of chlorophyll and carotenoids was improved. The biostimulant also mediates the accumulation of osmoprotectants and an increased leaf water content. Furthermore, the biostimulant effectively promotes tolerance by increasing drought-stress SIERF84 Transcription factor and decreasing both SIARF4 and SlWRKY81 transcript levels, which in turn, mediates stomatal closure. In addition, the up-regulation of key genes related to NO3- uptake (NTR1.1/2) and assimilation (NR) coupled with the downregulation of ammonium transporters' genes (AMT1.1/2), allowed the uptake of NO3- over NH4+ in the tolerant genotype which is likely to be associated with drought tolerance. Overall, the biostimulant was effective in alleviating water stress and showed similar effects to commercial chitosan. Besides the benefits of a circular economy framework, this biostimulant-based approach is innovative to promote a sustainable eco-agriculture, in the face of persistent water scarcity.

Molecular Communication of Microbial Plant Biostimulants in the Rhizosphere Under Abiotic Stress Conditions

Microbial plant biostimulants offer a promising, sustainable solution for enhancing plant growth and resilience, particularly under abiotic stress conditions such as drought, salinity, extreme temperatures, and heavy metal toxicity. These biostimulants, including plant growth-promoting rhizobacteria, mycorrhizal fungi, and nitrogen-fixing bacteria, enhance plant tolerance through mechanisms such as phytohormone production, nutrient solubilization, osmotic adjustment, and antioxidant enzyme activation. Advances in genomics, metagenomics, transcriptomics, and proteomics have significantly expanded our understanding of plant-microbe molecular communication in the rhizosphere, revealing mechanisms underlying these interactions that promote stress resilience. However, challenges such as inconsistent field performance, knowledge gaps in stress-related molecular signaling, and regulatory hurdles continue to limit broader biostimulant adoption. Despite these challenges, microbial biostimulants hold significant potential for advancing agricultural sustainability, particularly amid climate change-induced stresses. Future studies and innovation, including Clustered Regularly Interspaced Short Palindromic Repeats and other molecular editing tools, should optimize biostimulant formulations and their application for diverse agro-ecological systems. This review aims to underscore current advances, challenges, and future directions in the field, advocating for a multidisciplinary approach to fully harness the potential of biostimulants in modern agriculture.

Special Issue "Advances in the Physiology of Primary and Secondary Plant Metabolism Under Abiotic and Biotic Stress"

One of the most relevant areas of biology is the study of plant adaptation processes to the action of various stress factors of abiotic and biotic nature, which is reflected in the works of molecular biologists, geneticists, microbiologists, plant physiologists, and biochemists, as well as biotechnologists [...].

Phytotoxicity of HNTs to rice (Oryza sativa L.): Effects on rice growth and development

The phytotoxicity of halloysite nanotubes (HNTs) to rice (Oryza sativa L.) was evaluated at several stages from germination, seedling growth to spike setting, and the seedling stage was selected to study the effect of HNTs on the growth of rice. Rice was cultured using different concentrations of HNTs dispersions and a blank control group was cultured with deionized water. It was found that HNTs did not affect the germination of rice seeds, and at the seedling stage, the low concentration of HNTs dispersion (0.1 mg mL-1) promoted the growth of rice. This significantly increased the biomass and root system of rice seedlings and also promoted the development of stems and leaves of rice seedlings. However, high concentration of HNTs dispersion (100 mg mL-1) had an inhibitory effect on rice growth, resulting in a significant decrease in rice biomass, causing oxidative damage (increase in H2O2 content and malondialdehyde content, and disruption of cell membrane permeability), and causing a decrease in chlorophyll content in rice. The rice seedlings treated with HNTs were transplanted into the soil, and it was found that all the rice could grow healthily. The growth trend was consistent with the seedling stage, and all groups of rice were able to produce spikes, which indicated that the effect of HNTs on rice was slight. In total, this work displayed the toxicity of HNTs to rice, which lays the foundation for the application of HNTs in agricultural field.

Brassinosteroid improves light stress tolerance in tomato (Lycopersicon esculentum) by regulating redox status, photosynthesis and photosystem II

Plants often experience variations in light intensity, referred to as light stress, that negatively impact important aspects of plant growth and development, including photosynthesis and antioxidant system. The photosynthetic machinery is susceptible to these disturbances, especially photosystem II and its reaction centers. We aimed to evaluate the role of brassinosteriod in plants under both high and low light conditions by examining various physiological parameters such as photosynthetic efficiency, pigment levels, and enzymatic activity of various antioxidant enzymes in one month old tomato plants. We investigated various chlorophyll fluorescence parameters under low light (LL) and high light (HL) conditions and the associated gene expression related to photosynthesis, including plastocyanin, ferredoxin, and photosystem II oxygen-evolving enhancer protein 3 (PsbQ). Our results indicate that exogenous brassinosteroid application considerably increased tolerance to both high and low light stress in 4-week-old tomato as treated plants displayed enhanced photosynthesis, reduced oxidative damage, and increased antioxidant enzyme activity in comparison to control plants. Furthermore, brassinosteroid treatment enhanced the expression of genes associated with antioxidant pathways, which significantly contributed to the recovery of chlorophyll fluorescence parameters crucial for plant growth and development. Our results provide valuable insights into how brassinosteroid reduces light-induced stress in tomato plants.

Fighting to thrive via plant growth regulators: Green chemical strategies for drought stress tolerance

As global climate change intensifies, the occurrence and severity of various abiotic stresses will significantly threaten plant health and productivity. Drought stress (DS) is a formidable obstacle, disrupting normal plant functions through specific morphological, physiological, biochemical, and molecular mechanisms. Understanding how plants navigate DS is paramount to mitigating its adverse effects. In response to DS, plants synthesize or accumulate various plant growth regulators (PGRs), including phytohormones, neurotransmitters, gasotransmitters, and polyamines, which present promising sustainable green chemical strategies to adapt or tolerate stress conditions. These PGRs orchestrate crucial plant structure and function adjustments, activating defense systems and modulating cellular-level responses, transcript levels, transcription factors, metabolic genes, and stress-responsive candidate proteins. However, the efficacy of these molecules in mitigating DS depends on the plant species, applied PGR dose, treatment type, duration of DS exposure, and growth stages. Thus, exploring the integrated impact of PGRs on enhancing plant fitness and DS tolerance is crucial for global food security and sustainable agriculture. This review investigates plant responses to DS, explains the potential of exogenously applied diverse PGRs, dissects the complex chemistry among PGRs, and sheds light on omics approaches for harnessing the molecular basis of DS tolerance. This updated review delivers comprehensive mechanistic insights for leveraging various PGRs to enhance overall plant fitness under DS conditions.

Synergistic effects of SAP and PGPR on physiological characteristics of leaves and soil enzyme activities in the rhizosphere of poplar seedlings under drought stress

Super absorbent polymers (SAP) provide moisture conditions that allow plant growth-promoting rhizobacteria (PGPR) to enter the soil for acclimatization and strain propagation. However, the effects of SAP co-applied with PGPR on the physiological characteristics of leaves and rhizosphere soil enzyme activities of poplar seedlings are not well understood. Here, a pot experiment using one-year-old poplar seedlings with five treatments, normal watering, drought stress (DR), drought stress + SAP (DR+SAP), drought stress + Priestia megaterium (DR +PGPR) and drought stress + SAP + P. megaterium (DR+S+P), was performed to analyze the contents of non-enzymatic antioxidants, osmotic regulators and hormones in leaves, as well as rhizosphere soil enzyme activities. Compared with normal watering, the DR treatment significantly decreased the contents of dehydroascorbate (DHA; 19.08%), reduced glutathione (GSH; 14.18%), oxidized glutathione, soluble protein (26.84%), indoleacetic acid (IAA; 9.47%), gibberellin (GA) and zeatin (ZT), the IAA/abscisic acid (ABA), GA/ABA, ZT/ABA and (IAA+GA+ZT)/ABA (34.67%) ratios in leaves, and the urease and sucrase activities in the rhizosphere soil. Additionally, it significantly increased the soluble sugar, proline and ABA contents in leaves. However, in comparison with the DR treatment, the DR+S+P treatment significantly increased the DHA (29.63%), GSH (15.13%), oxidized glutathione, soluble protein (29.15%), IAA (12.55%) and GA contents, the IAA/ABA, GA/ABA, ZT/ABA and (IAA+GA+ZT)/ABA (46.85%) ratios in leaves, and the urease, sucrose and catalase activities in rhizosphere soil to different degrees. The soluble sugar, proline and ABA contents markedly reduced in comparison to the DR treatment. The effects of the DR+SAP and DR+PGPR treatments were generally weaker than those of the DR+S+P treatment. Thus, under drought-stress conditions, the simultaneous addition of SAP and P. megaterium enhanced the drought adaptive capacities of poplar seedlings by regulating the non-enzymatic antioxidants, osmotic regulators, and endogenous hormone content and balance in poplar seedling leaves, as well as by improving the rhizosphere soil enzyme activities.

Codonopsis pilosula seedling drought- responsive key genes and pathways revealed by comparative transcriptome

Background

Codonopsis pilosula (Campanulaceae) is a traditional herbal plant that is widely used in China, and the drought stress during the seedling stage directly affects the quality, ultimately impacting its yield. However, the molecular mechanisms underlying the drought resistance of C. pilosula seedlings remain unclear.

Method

Herein, we conducted extensive comparative transcriptome and physiological studies on two distinct C. pilosula cultivar (G1 and W1) seedlings subjected to a 4-day drought treatment.

Results

Our findings revealed that cultivar G1 exhibited enhanced retention of proline and chlorophyll, alongside a marked elevation in peroxidase activity, coupled with diminished levels of malondialdehyde and reduced leaf relative electrolyte leakage compared with cultivar W1. This suggested that cultivar G1 had relatively higher protective enzyme activity and ROS quenching capacity. We discerned a total of 21,535 expressed genes and identified 4,192 differentially expressed genes (DEGs) by RNA sequencing (RNA-seq). Our analysis revealed that 1,764 DEGs unique to G1 underwent thorough annotation and functional categorization utilizing diverse databases. Under drought conditions, the DEGs in G1 were predominantly linked to starch and sucrose metabolic pathways, plant hormone signaling, and glutathione metabolism. Notably, the drought-responsive genes in G1 were heavily implicated in hormonal modulation, such as ABA receptor3-like gene (PYL9), regulation by transcription factors (KAN4, BHLH80, ERF1B), and orchestration of drought-responsive gene expression. These results suggest that cultivar G1 possesses stronger stress tolerance and can better adapt to drought growing conditions. The congruence between qRT-PCR validation and RNA-seq data for 15 DEGs further substantiated our findings.

Conclusion

Our research provides novel insights into the physiological adaptations of C. pilosula to arid conditions and lays the groundwork for the development of new, drought-tolerant C. pilosula cultivars.

Comparative Study on the Response of Hyssop (Hyssopus officinalis L.), Salvia (Salvia officinalis L.), and Oregano (Origanum vulgare L.) to Drought Stress Under Foliar Application of Selenium

Drought is one of the most important abiotic factors limiting plant productivity. Although the aromatic plants of the Lamiaceae family often grow in arid regions, drought tolerance varies greatly among the different species of this family. The effect of induced drought stress can be reduced by the application of selenium. The current study aims to compare the growth and biochemical responses of three species of the Lamiaceae family (hyssop, salvia, and oregano) to drought stress and the possibility of reducing the effect of stress in these plants by foliar treatment with selenium. Drought stress reduced the fresh and dry biomass of hyssop (by 35% and 15%), salvia (by 45% and 41%), and oregano (by 51% and 32%). Se treatment did not affect the growth of plants under drought stress, but it improved relative water content in hyssop and salvia under moderate drought conditions. A reduction in the content of chlorophyll a and chlorophyll b (in hyssop and salvia). In addition, an increase in the content of hydrogen peroxide (in oregano and salvia), malondialdehyde, and proline in plants cultivated under drought conditions was observed. Se treatment led to reduced levels of hydrogen peroxide and malondialdehyde, along with an increase in chlorophyll a content (in hyssop and oregano) and proline content. The response of the antioxidant system depended on the plant species. Hyssop exhibited a significant increase in glutathione peroxidase, superoxide dismutase, and peroxidase activities. Oregano showed enhanced catalase activity. Salvia experienced a sharp increase in ascorbic acid content. Se treatment stimulated the accumulation of phenolic compounds and increased glutathione peroxidase activity in all studied species.

TaCDPK1-5A positively regulates drought response through modulating osmotic stress responsive-associated processes in wheat (Triticum aestivum)

KEY MESSAGE

Wheat TaCDPK1-5A plays critical roles in mediating drought tolerance through regulating osmotic stress-associated physiological processes. Calcium (Ca2+) acts as an essential second messenger in plant signaling pathways and impacts plant abiotic stress responses. This study reported the function of TaCDPK1-5A, a calcium-dependent protein kinase (CDPK) gene in T. aestivum, in mediating drought tolerance. TaCDPK1-5A sensitively responded to drought and exogenous abscisic acid (ABA) signaling, displaying induced transcripts in plants under drought and ABA treatments. Yeast two-hybrid and co-immunoprecipitation assays revealed that TaCDPK1-5A interacts with the mitogen-activated protein kinase TaMAPK4-7D whereas the latter with ABF transcription factor TaABF1-3A, suggesting that TaCDPK1-5A constitutes a signaling module with above partners to transduce signals initiated by drought/ABA stressors. Overexpression of TaCDPK1-5A, TaMAPK4-7D and TaABF1-3A enhanced plant drought adaptation by modulating the osmotic stress-related physiological indices, including increased osmolyte contents, enlarged root morphology, and promoted stomata closure. Yeast one-hybrid assays indicated the binding ability of TaABF1-3A with promoters of TaP5CS1-1B, TaPIN3-5A, and TaSLAC1-3-2A, the genes encoding P5CS enzyme, PIN-FORMED protein, and slow anion channel, respectively. ChIP-PCR and transcriptional activation assays confirmed that TaABF1-3A regulates these genes at transcriptional level. Moreover, transgene analysis indicated that these stress-responsive genes positively regulated proline biosynthesis (TaP5CS1-1B), root morphology (TaPIN3-5A), and stomata closing (TaSLAC1-3-2A) upon drought signaling. Positive correlations were observed between yield and the transcripts of TaCDPK1-5A signaling partners in wheat cultivars under drought condition, with haplotype TaCDPK1-5A-Hap1 contributing to improved drought tolerance. Our study concluded that TaCDPK1-5A positively regulates drought adaptation and is a valuable target for molecular breeding the drought-tolerant cultivars in T. aestivum.

Microbial-assistance and chelation-support techniques promoting phytoremediation under abiotic stresses

Phytoremediation, the use of plants to remove heavy metals from polluted environments, has been extensively studied. However, abiotic stresses such as drought, salt, and high temperatures can limit plant growth and metal uptake, reducing phytoremediation efficiency. High levels of HMs are also toxic to plants, further decreasing phytoremediation efficacy. This manuscript explores the potential of microbial-assisted and chelation-supported approaches to improve phytoremediation under abiotic stress conditions. Microbial assistance involves the use of specific microbes, including fungi that can produce siderophores. Siderophores bind essential metal ions, increasing their solubility and bioavailability for plant uptake. Chelation-supported methods employ organic acids and amino acids to enhance soil absorption and supply of essential metal ions. These chelating agents bind HMs ions, reducing their toxicity to plants and enabling plants to better withstand abiotic stresses like drought and salinity. Managed microbial-assisted and chelation-supported approaches offer more efficient and sustainable phytoremediation by promoting plant growth, metal uptake, and mitigating the effects of heavy metal and abiotic stresses. Managed microbial-assisted and chelation-supported approaches offer more efficient and sustainable phytoremediation by promoting plant growth, metal uptake, and mitigating the effects of HMs and abiotic stresses.These strategies represent a significant advancement in phytoremediation technology, potentially expanding its applicability to more challenging environmental conditions. In this review, we examined how microbial-assisted and chelation-supported techniques can enhance phytoremediation a method that uses plants to remove heavy metals from contaminated sites. These approaches not only boost plant growth and metal uptake but also alleviate the toxic effects of HMs and abiotic stresses like drought and salinity. By doing so, they make phytoremediation a more viable and effective solution for environmental remediation.

Monitoring the temporal variations of plant stress using the air pollution tolerance index in the Sejzi industrial area (Isfahan, Iran)

The objective of this study was to screen air pollution-induced stress in some plant species in the Sejzi industrial region (Isfahan, Iran). An assessment of APTI and other physiological and biochemical features of significant species in the area was conducted across three seasons: spring, summer, and autumn. The physiological and biochemical factors of the following species were evaluated: Limonium persicum, Atriplex lentiformis, Nitraria schoberi, Haloxylon persicum, Tamarix hispida, Zygophyllum atriplicoides, Karelinia caspica, and Prosopis farcta. The physiological factors assessed included acidity and relative humidity content, while the biochemical factors assessed included proline, sugar, ascorbic acid, and total chlorophyll. Subsequently, a thorough evaluation was carried out on the species under investigation to ascertain their biomonitors' capabilities and APTI. The study findings indicated that the species P. farcta, N. schoberi, and K. caspica consistently had high APTI values during the spring, autumn, and summer seasons, classifying them as tolerant plant species. Conversely, the observed traits showed significant fluctuations across the seasons. The investigation's findings indicate that the species L. persicum, N. schoberi, and K. caspica exhibit higher annual averages of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid compared to other species. The examination of the annual variation in the tolerance levels of plant species to pollution ranked from highest to lowest was as follows: N. schoberi, P. farcta, K. caspica, Z. atriplicoides, H. persicum, T. hispida, L. persicum, and A. lentiformis. Moreover, based on the annual average, the primary determinants that impact the APTI in the species being studied include ascorbic acid (35%), leaf acidity (19%), total chlorophyll content (35%), and relative humidity content (69%). Furthermore, a distinct and significant correlation was found between proline and sugar levels and the annual APTI values. Additionally, the species P. farcta had the highest API compared to other species. The study revealed the high potential of some plant species against air pollution induced stress which can be used in air and dust pollution management in the region.

Chitosan-thiourea and their derivatives: Applications and action mechanisms for imparting drought tolerance

The increasing abiotic stresses from changing global climatic conditions, including drought, extreme temperatures, salinity, storms, pollutants, and floods, impend crop cultivation and sustainability. To mitigate these effects, numerous synthetic and non-synthetic chemicals or plant growth regulators are in practice. Chitosan, a natural organic substance rich in nitrogen and carbon, and thiourea, a synthetic plant growth regulator containing sulfur and nitrogen, have garnered significant interest for their roles in enhancing plant stress tolerance. Despite extensive use, the precise mechanisms of their actions remain unclear. Towards this endeavor, the present review examines how chitosan and thiourea contribute to stress tolerance in crop plants, particularly under drought conditions, to improve production and sustainability. It also explores thiourea's potential as a hydrogen sulfide (H2S) donor and the possible applications of thiolated chitosan derivatives and chitosan-thiourea combinations, emphasizing their biological functions and benefits for sustainable agriculture.

Evaluation of growth, physiological response, and drought resistance of different flue-cured tobacco varieties under drought stress

Background

In recent years, more severe droughts have occurred frequently in many parts of the world, drought stress is the primary abiotic stress factor restricting the growth and quality of flue-cured tobacco. Therefore, screening dryland cultivation-compatible flue-cured tobacco varieties will help reduce the negative impact of drought.

Methods

Tobacco varieties were selected: Qinyan 96 (Q96), Zhongyan 101 (Z101), Yunyan 87 (Y87), and Yunyan 116 (Y116). A pot experiment was conducted with four water supply gradients: sufficient, mild stress, moderate stress, and severe stress. The aim was to analyze inter-varietal differences in agronomic traits, photosynthetic traits, reactive oxygen species (ROS) metabolism, and antioxidant enzyme system under drought stress. Additionally, the drought resistance of four flue-cured tobacco varieties was evaluated using principal component analysis and membership function analysis.

Results

The results showed that drought intensification inhibited seedling growth and development across all varieties, with Q96 showing the least decrease and Y116 the greatest. With the increasing degree of drought stress, photosynthetic rates (Pn), transpiration rate (Tr), and stomatal conduction (Gs) have shown gradually decreasing trends, while substomatal cavity CO2 concentration (Ci) showed a growing trend. Severe drought corresponded with lower chlorophyll content and decreased the maximal photochemical efficiency (Fv/Fm), photosystem II (PSII), and photochemical quenching coefficient (qP) in all varieties, while steady-state non-photochemical quenching (NPQ) increased. Increased drought stress led to significantly higher reactive oxygen species (ROS) and malondialdehyde (MDA) content accumulation in tobacco seedlings. The antioxidant enzyme activities in, Q96, Z101, and Y87 increased under mild drought stress, whereas Y116 showed decreased activity.

Conclusion

The drought resistance ranking among the four varieties is as follows: Q96 > Z101 > Y87 > Y116. Therefore, Q96 is a promising drought-tolerant breeding material that can be used as a reference for dryland cultivation of flue-cured tobacco.

Metabolomic and Physiological Analyses Reveal the Effects of Different Storage Conditions on Sinojackia xylocarpa Hu Seeds

BACKGROUNDS

Sinojackia xylocarpa Hu is a deciduous tree in the Styracaceae family, and it is classified as a Class II endangered plant in China. Seed storage technology is an effective means of conserving germplasm resources, but the effects of different storage conditions on the quality and associated metabolism of S. xylocarpa seeds remain unclear. This study analyzed the physiological and metabolic characteristics of S. xylocarpa seeds under four storage conditions.

RESULTS

Our findings demonstrate that reducing seed moisture content and storage temperature effectively prolongs storage life. Seeds stored under that condition exhibited higher internal nutrient levels, lower endogenous abscisic acid (ABA) hormone levels, and elevated gibberellic acid (GA3) levels. Additionally, 335 metabolites were identified under four different storage conditions. The analysis indicates that S. xylocarpa seeds extend seed longevity and maintain cellular structural stability mainly by regulating the changes in metabolites related to lipid, amino acid, carbohydrate, and carotenoid metabolic pathways under the storage conditions of a low temperature and low seed moisture.

CONCLUSIONS

These findings provide new insights at the physiological and metabolic levels into how these storage conditions extend seed longevity while also offering effective storage strategies for preserving the germplasm resources of S. xylocarpa.

Intersecting planetary health: Exploring the impacts of environmental stressors on wildlife and human health

This comprehensive review articulates critical insights into the nexus of environmental stressors and their health impacts across diverse species, underscoring significant findings that reveal profound effects on both wildlife and human health systems. Central to our examination is the role of pollutants, climate variables, and pathogens in contributing to complex disease dynamics and physiological disruptions, with particular emphasis on immune and endocrine functions. This research brings to light emerging evidence on the severe implications of environmental pressures on a variety of taxa, including predatory mammals, raptorial birds, seabirds, fish, and humans, which are pivotal as indicators of broader ecosystem health and stability. We delve into the nuanced interplay between environmental degradation and zoonotic diseases, highlighting novel intersections that pose significant risks to biodiversity and human populations. The review critically evaluates current methodologies and advances in understanding the morphological, histopathological, and biochemical responses of these organisms to environmental stressors. We discuss the implications of our findings for conservation strategies, advocating for a more integrated approach that incorporates the dynamics of zoonoses and pollution control. This synthesis not only contributes to the academic discourse but also aims to influence policy by aligning with the Global Goals for Sustainable Development. It underscores the urgent need for sustainable interactions between humans and their environments, which are critical for preserving biodiversity and ensuring global health security. By presenting a detailed analysis of the interdependencies between environmental stressors and biological health, this review highlights significant gaps in current research and provides a foundation for future studies aimed at mitigating these pressing issues. Our study is significant as it proposes integrative and actionable strategies to address the challenges at the intersection of environmental change and public health, marking a crucial step forward in planetary health science.

Combined application of biochar and peatmoss for mitigation of drought stress in tobacco

Drought poses a significant ecological threat that limits the production of crops worldwide. The objective of this study to examine the impact of soil applied biochar (BC) and peatmoss (PM) on the morpho-biochemical and quality traits of tobacco plants under drought conditions. In the present experiment work, a pot trial was conducted with two levels of drought severity (~ well-watered 75 ± 5% field capacity) and severe drought stress (~ 35 ± 5% field capacity), two levels of peatmoss (PM) @ 5% [PM+ (with peatmoss) and PM- (without peatmoss)] and three levels of rice straw biochar (BC0 = no biochar; BC1 = 150 mg kg- 1; and BC2 = 300 mg kg- 1 of soil) in tobacco plants. The results indicate that drought conditions significantly impacted the performance of tobacco plants. However, the combined approach of BC and PM significantly improved the growth, biomass, and total chlorophyll content (27.94%) and carotenoids (32.00%) of tobacco. This study further revealed that the drought conditions decreased the production of lipid peroxidation and proline accumulation. But the synergistic approach of BC and PM application increased soluble sugars (17.63 and 12.20%), soluble protein (31.16 and 15.88%), decreased the proline accumulation (13.92 and 9.03%), and MDA content (16.40 and 8.62%) under control and drought stressed conditions, respectively. Furthermore, the combined approach of BC and PM also improved the leaf potassium content (19.02%) by limiting the chloride ions (33.33%) under drought stressed conditions. Altogether, the balanced application of PM and BC has significant potential as an effective approach and sustainable method to increase the tolerance of tobacco plants subjected to drought conditions. This research uniquely highlights the combined potential of PM and BC as an eco-friendly strategy to enhance plant resilience under drought conditions, offering new insights into sustainable agricultural practices.

Rhizobacterial diversity of Portuguese olive cultivars in the Douro valley and their potential as plant growth promoters

AIMS

This study investigated the bacterial communities in the rhizosphere of two traditional Portuguese olive cultivars, Cobrançosa and Negrinha de Freixo, in relation to soil properties. Additionally, we aimed to isolate and identify bacteria with potential for biocontrol and other plant growth-promoting traits from these rhizosphere communities.

METHODS AND RESULTS

Bacterial communities in the olive rhizosphere were investigated using a metabarcoding approach and the soil physicochemical properties of the olive groves were also analyzed. Higher bacterial richness was associated with Negrinha de Freixo growing in soil with high organic matter content and water-holding capacity. In contrast, the soils of the Cobrançosa grove presented higher pH and electric conductivity. Negrinha de Freixo rhizosphere was enriched with ASVs (Amplicon Sequence Variants) belonging to Bacillus, Gaiella, Acidothermus, Bradyrhizobium, and uncultured Xanthobacteraceae. On the other hand, the Cobrançosa rhizosphere was characterized by higher relative abundance of Streptomyces and Sphingomonas. Bacterial isolation from the rhizosphere and screening for plant growth-promoting activities were also performed. Six bacteria strains, predominantly Bacillus isolated from Negrinha de Freixo, demonstrated antagonistic activities against the olive fungal pathogen Colletotrichum gloeosporoides and other plant growth promotion (PGP) traits.

CONCLUSIONS

Our findings demonstrate that the structure of rhizosphere bacterial communities associated with olive trees is shaped by both plant cultivar and soil-related factors. The higher number of bacterial species in the rhizosphere of Negrinha de Freixo was related to a higher organic matter content and a greater abundance of isolates with plant growth promotion traits, particularly Bacillus strains.

Abscisic acid improves drought resilience, growth, physio-biochemical and quality attributes in wheat (Triticum aestivum L.) at critical growth stages

Wheat is an important staple crop not only in Pakistan but all over the globe. Although the area dedicated to wheat cultivation expands annually, the quantity of wheat harvested is declining due to various biotic and abiotic factors. Global wheat production and output have suffered as a result of the drought, which is largely driven by a lack of water and environmental factors. Organic fertilizers have been shown to reduce the severity of drought. The current research was conducted in semi-arid climates to mitigate the negative effects of drought on wheat during its critical tillering (DTS), flowering (DFS), and grain filling (DGFS) stages through the application of three different abscisic acid treatments: ABA0 (0 mgL-1) control, ABA1 (100 mgL-1) and ABA2 (200 mgL-1). Wheat growth and yield characteristics were severely harmed by drought stress across all critical development stages, with the DGFS stage being particularly vulnerable and leading to a considerable loss in yield. Plant height was increased by 24.25%, the number of fertile tillers by 25.66%, spike length by 17.24%, the number of spikelets per spike by 16.68%, grain count per spike by 11.98%, thousand-grain weight by 14.34%, grain yield by 26.93% and biological yield by 14.55% when abscisic acid (ABA) was applied instead of the control treatment. Moreover, ABA2 increased the more physiological indices (water use efficiency (36.12%), stomatal conductance (44.23%), chlorophyll a (24.5%), chlorophyll b (29.8%), transpiration rate (23.03%), photosynthetic rate (24.84%), electrolyte leakage (- 38.76%) hydrogen peroxide (- 18.09%) superoxide dismutase (15.3%), catalase (20.8%), peroxidase (- 18.09%), and malondialdehyde (- 13.7%)) of drought-stressed wheat as compared to other treatments. In the case of N, P, and K contents in grain were maximally improved with the application of ABA2. Through the use of principal component analysis, we were able to correlate our results across scales and provide an explanation for the observed effects of ABA on wheat growth and production under arid conditions. Overall, ABA application at a rate of 200 mgL-1 is an effective technique to boost wheat grain output by mitigating the negative effects of drought stress.

Identification of autophagy gene family in potato and the role of StATG8a in salt and drought stress

Autophagy is a highly conserved method of recycling cytoplasm components in eukaryotes. It plays an important role in plant growth and development, as well as in response to biotic and abiotic stresses. Although autophagy-related genes (ATGs) have been identified in several crop species, their particular role in potato (Solanum tuberosum L.) remains unclear. Several transcription factors and signaling genes in the transgenic lines of the model plant Arabidopsis thaliana, such as AtTSPO, AtBES1, AtPIP2;7, AtCOST1 as well as AtATI1/2, ATG8f, GFP-ATG8F-HA, AtDSK2, AtNBR1, AtHKT1 play crucial functions under drought and salt stresses, respectively. In this study, a total of 29 putative StATGs from 15 different ATG subfamilies in the potato genome were identified. Their physicochemical properties, evolutionary connections, chromosomal distribution, gene duplication, protein-protein interaction network, conserved motifs, gene structure, interspecific collinearity relationship, and cis-regulatory elements were analyzed. The results of qRT-PCR detection of StATG expression showed that 29 StATGs were differentially expressed in potato's leaves, flowers, petiole, stem, stolon, tuber, and root. StATGs were dynamically modulated by salt and drought stresses and up-regulated under salt and drought conditions. Our results showed that the StATG8a localized in the cytoplasm and the nucleus. Potato cultivar "Atlantic" overexpressing or downregulating StATG8a were constructed. Based on physiological, biochemical, and photosynthesis parameters, potato lines overexpressing StATG8a exhibited 9 times higher drought and salt tolerance compared to non-transgenic plants. In contrast, the potato plants with knockdown expression showed a downtrend in drought and salt tolerance compared to non-transgenic potato lines. These results could provide new insights into the function of StATG8a in salt and drought response and its possible mechanisms.

Volatile compounds in citrus in adaptation to water deficit and to herbivory by Diaphorina citri: How the secondary metabolism of the plant is modulated under concurrent stresses. A review

Citrus plants are grown in diverse regions of the world, from subtropical to semi-arid and humid tropical areas. Through mechanisms essential for their survival, they adapt to the environmental conditions to which they are subjected. Although there is vast literature on adaptation of citrus plants to individual stresses, plant responses to interaction among different types of stresses have not been clearly examined. Abiotic or biotic stresses, or a combination of these stresses, result in reorganization of plant energy resources for defense, whether it be for resistance, tolerance, or prevention of stress. Plants generally respond to these stress factors through production of secondary metabolites, such as volatile compounds, derived from different biosynthesis and degradation pathways, which are released through distinct routes. Volatile compounds vary among plant species, meeting the specific needs of the plant. Simultaneous exposure to the stress factors of water deficit and herbivory leads to responses such as qualitative and quantitative changes in the emission of secondary metabolites, and compounds may accumulate within the leaves or predispose the plant to more quickly respond to the stress brought about by the herbivore. The genetic makeup of citrus plants can contribute to a better response to stress factors; however, studies on the emission of volatile compounds in different citrus genotypes under simultaneous stresses are limited. This review examines the effects of abiotic stress due to water deficit and biotic stress due to herbivory by Diaphorina citri in citrus plants and examines their connection with volatile compounds. A summary is made of advances in knowledge regarding the performance of volatile compounds in plant defense against both stress factors, as well as the interaction between them and possible findings in citrus plants. In addition, throughout this review, we focus on how genetic variation of the citrus species is correlated with production of volatile compounds to improve stress tolerance.

Identification of urban street trees for green belt development for optimizing pollution mitigation in Delhi, India

The current study evaluated the effects of air pollution on selected street trees in the National Capital Territory during the pre- and post-monsoon seasons to identify the optimally suitable tree for green belt development in Delhi. The identification was performed by measuring the air pollution tolerance index (APTI), anticipated performance index (API), dust-capturing capacity (DCC) and proline content on the trees. The APTI of street trees of Delhi varied significantly among different tree species (F11,88.91 = 47.18, p < 0.05), experimental sites (F3,12.52 = 6.65, p < 0.001) and between seasons (F1,31.12 = 16.51, p < 0.001), emphasizing the relationships between trees and other types of variables such as the climate and level of pollution, among other factors. This variability emphasizes the need to choose trees to use for urban greening in the improvement of air quality in different environments within cities. Ascorbic acid (AA) concentration and relative water content (RWC) had a strong influence on APTI with an extremely significant moderate positive correlation between AA concentration and APTI (r = 0.65, p < 0.001) along with RWC and APTI (r = 0.52, p < 0.001), indicating that higher levels of AA concentration and RWC are linked to increased air pollution tolerance. The PCA bi-plot indicates AA has poor positive loading coefficients with PC1 explaining 29.49% of the total variance in the dataset. The highest APTI was recorded in Azadirachta indica (22.01), Leucaena leucocephala (20.65), Morus alba (20.62), Ficus religiosa (20.61) and Ficus benghalensis (19.61), irrespective of sites and seasons. Similarly, based on API grading, F. religiosa and F. benghalensis were identified as excellent API grade 6 (81-90%), A. indica and Alstonia scholaris as very good API grade 5 (71-80%), M. alba, Pongamia pinnata and Monoon longifolium as good API grade 4 (61-70%) and Plumeria alba as moderate API grade 3 (51-60%) in different streets of Delhi. As these plants are indigenous to the region and hold significant socio-economic and aesthetic significance in Indian societies, they are advisable for avenue plantations as part of various government initiatives to support environmental sustainability.

Expanding roles of cross-talk between hydrogen sulfide and nitric oxide under abiotic stress in plants

Abiotic stress such as salt, heavy metals, drought, temperature, and others can affect plants from seed germination to seedling growth to reproductive maturity. Abiotic stress increases reactive oxygen species and lowers antioxidant enzymes in plants resulted the plant tolerance ability against stress conditions decrease. Hydrogen sulfide (H2S) and nitric oxide (NO) are important gasotransmitters involved in seed germination, photosynthesis, growth and development, metabolism, different physiological processes and functions in plants. In plants, various enzymes are responsible for the biosynthesis of both H2S and NO via both enzymatic and non-enzymatic pathways. They also mediate post-translation modification, such as persulfidation, and nitrosylation, which are protective mechanisms against oxidative damage. They also regulate some cellular signalling pathways in response to various abiotic stress. H2S and NO also stimulate biochemical reactions in plants, including cytosolic osmoprotectant accumulation, reactive oxygen species regulation, antioxidant system activation, K+ uptake, and Na+ cell extrusion or vacuolar compartmentation. In this review, we summarize how H2S and NO interact with each other, the function of both H2S and NO, the mechanism of biosynthesis, and post-translational modification under different abiotic stress. Our main emphasis was to find the cross-talk between NO and H2S and how they regulate genes in plants under abiotic stress.

Radiation synthesis of sodium alginate/gelatin based ultra-absorbent hydrogel for efficient water and nitrogen management in wheat under drought stress

The main focus of this study was on using radiation to make an ultra-absorbent hydrogel (UAH) from sodium alginate (SA) and gelatin (GL) biopolymers. This UAH can effectively handle water and nitrogen in wheat farming during drought stress. The hydrogel was synthesized by gamma irradiation-induced SA/GL/polyacrylamide crosslinking at 10-40 kGy. Varying SA/GL ratios affected swelling and the gel fraction of SA/GL/PAm hydrogels. The (SA/GL 17/83) hydrogel exhibited a 40.03 g/g swelling degree, while increasing SA content resulted in higher swelling, peaking at 75.5 g/g for (SA/GL 83/17). This indicated a synergistic interaction between SA and GL. The gel fraction also increased from 76.8 to 90.3%, with a higher GL content reflecting increased crosslinking. After multiple hydrolysis cycles, the hydrogel achieved 1293 (g/g) swelling and 36 days of water retention. When applied to wheat (Triticuma estivum) under drought stress, it significantly improved shoot length (18%), root length (43%), shoot fresh weight (49%), and shoot dry weight (51%) under extreme drought. The significant increases in protein and carbohydrate content in both shoots (up to 32% and 19%, respectively) and grains (up to 21% and 24%, respectively), along with the reduction in proline content (up to 38%), demonstrate that ultra-absorbent hydrogel (UAH) effectively enhances nitrogen content, photosynthesis, and overall plant health in wheat under varying drought stress levels. This novel SA/GL-based UAH holds promise for addressing water scarcity and agricultural challenges, offering a sustainable solution for water and nitrogen management under drought stress.

Combining proximal and remote sensing to assess 'Calatina' olive water status

Developing an efficient and sustainable precision irrigation strategy is crucial in contemporary agriculture. This study aimed to combine proximal and remote sensing techniques to show the benefits of using both monitoring methods, simultaneously assessing the water status and response of 'Calatina' olive under two distinct irrigation levels: full irrigation (FI), and drought stress (DS, -3 to -4 MPa). Stem water potential (Ψstem) and stomatal conductance (gs) were monitored weekly as reference indicators of plant water status. Crop water stress index (CWSI) and stomatal conductance index (Ig) were calculated through ground-based infrared thermography. Fruit gauges were used to monitor continuously fruit growth and data were converted in fruit daily weight fluctuations (ΔW) and relative growth rate (RGR). Normalized difference vegetation index (NDVI), normalized difference RedEdge index (NDRE), green normalized difference vegetation index (GNDVI), chlorophyll vegetation index (CVI), modified soil-adjusted vegetation index (MSAVI), water index (WI), normalized difference greenness index (NDGI) and green index (GI) were calculated from data collected by UAV-mounted multispectral camera. Data obtained from proximal sensing were correlated with both Ψstem and gs, while remote sensing data were correlated only with Ψstem. Regression analysis showed that both CWSI and Ig proved to be reliable indicators of Ψstem and gs. Of the two fruit growth parameters, ΔW exhibited a stronger relationship, primarily with Ψstem. Finally, NDVI, GNDVI, WI and NDRE emerged as the vegetation indices that correlated most strongly with Ψstem, achieving high R2 values. Combining proximal and remote sensing indices suggested two valid approaches: a more simplified one involving the use of CWSI and either NDVI or WI, and a more comprehensive one involving CWSI and ΔW as proximal indices, along with WI as a multispectral index. Further studies on combining proximal and remote sensing data will be necessary in order to find strategic combinations of sensors and establish intervention thresholds.

Stress mitigation mechanism of rice leaf microbiota amid atmospheric deposition of heavy metals

Leaf microbiota have been extensively applied in the biological control of plant diseases, but their crucial roles in mitigating atmospheric heavy metal (HM) deposition and promoting plant growth remain poorly understood. This study demonstrates that elevated atmospheric HM deposition on rice leaves significantly shapes distinct epiphytic and endophytic microbiota across all growth stages. HM stress consistently leads to the dominance of epiphytic Pantoea and endophytic Microbacterium in rice leaves, particularly during the booting and filling stages. Leaf-bound HMs stimulate the differentiation of specialized microbial communities in both endophytic and epiphytic compartments, thereby regulating leaf microbial interactions. Metagenomic binning retrieved high-quality genomes of keystone leaf microorganisms, indicating their potential for essential metabolic functions. Notably, Pantoea and Microbacterium show significant HM resistance, plant growth-promoting capabilities, and diverse element cycling functions. They possess genes associated with metal(loid) resistance, such as ars and czc, suggesting their ability to detoxify arsenic(As) and cadmium(Cd). They also support carbon, nitrogen, and sulfur cycling, with genes linked to carbon fixation, nitrogen fixation, and sulfur reduction. Additionally, these bacteria may enhance plant stress resistance and growth by producing antioxidants, phytohormones, and other beneficial compounds, potentially improving HM stress tolerance and nutrient availability in rice plants. This study shows that atmospheric HMs affect rice leaf microbial communities, prompting plants to seek microbial help to combat stress. The unique composition and metabolic potential of rice leaf microbiota offer a novel perspective for mitigating adverse stress induced by atmospheric HM deposition. This contributes to the utilization of leaf microbiota to alleviate the negative impact of heavy metal deposition on rice development and food security.

Surface modified ZnO NPs by betaine and proline build up tomato plants against drought stress and increase fruit nutritional quality

Drought stress is a serious challenge for global food production. Nanofertilizers and nanocomposites cope with such environmental stresses and also increase nutritional contents of fruits. An in vitro experiment was designed to use Zinc Oxide Nanoparticles (ZnO NPs) primed with Proline and Betaine (ZnOP and ZnOBt NPs) at 50 and 100 mg/kg soil against drought stress in Tomato (Solanum lycopersicum) plants. Plant morphological, biochemical, and fruit nutritional quality were accessed. Maximum plant height was observed under the treatment of ZnOP50 (1.09 m) and ZnO 100 (1.06 m). ZnOP and ZnOBt also improved the chlorophyll content up to 86% and 87.16%, respectively. Application of ZnOP NPs also demonstrated maximum tomato yield (204 g tomato/plant) followed by ZnO NPs and ZnOBt NPs. Nanocomposites decreased phenolics and flavonoids contents in drought stressed plants demonstrating the mitigation of oxidative stress. Nanofertilizer also increased the concentration of phenolics and flavonoids in fruits that increased the nutritional contents. Furthermore a significant accumulation of betaine, proline, and lycopene in fruits on nanocomposite treatment made it nutritional and healthy. Lycopene content increased up to 2.01% and 1.23% in presence of ZnOP50 and ZnOP100, respectively. These outcomes validate that drought stress in plant can be reduced by accumulation of different phytochemicals and quenching oxidative stress. The study deems that nano zinc carrying osmoregulators can greatly reduce the negative effects of drought stress and increase nutritional quality of tomato fruits.

Genome-Wide Association Analysis Identified Quantitative Trait Loci (QTLs) Underlying Drought-Related Traits in Cultivated Peanut (Arachis hypogaea L.)

Drought is a destructive abiotic stress that affects all critical stages of peanut growth such as emergence, flowering, pegging, and pod filling. The development of a drought-tolerant variety is a sustainable strategy for long-term peanut production. The U.S. mini-core peanut germplasm collection was evaluated for drought tolerance to the middle-season drought treatment phenotyping for pod weight, pod count, relative water content (RWC), specific leaf area (SLA), leaf dry matter content (LDMC), and drought rating. A genome-wide association study (GWAS) was performed to identify minor and major QTLs. A total of 144 QTLs were identified, including 18 significant QTLs in proximity to 317 candidate genes. Ten significant QTLs on linkage groups (LGs) A03, A05, A06, A07, A08, B04, B05, B06, B09, and B10 were associated with pod weight and pod count. RWC stages 1 and 2 were correlated with pod weight, pod count, and drought rating. Six significant QTLs on LGs A04, A07, B03, and B04 were associated with RWC stages 1 and 2. Drought rating was negatively correlated with pod yield and pod count and was associated with a significant QTL on LG A06. Many QTLs identified in this research are novel for the evaluated traits, with verification that the pod weight shared a significant QTL on chromosome B06 identified in other research. Identified SNP markers and the associated candidate genes provide a resource for molecular marker development. Verification of candidate genes surrounding significant QTLs will facilitate the application of marker-assisted peanut breeding for drought tolerance.

Assessing the responses of ecosystem patterns, structures and functions to drought under climate change in the Yellow River Basin, China

Understanding how ecosystems respond and adapt to drought has become an urgent issue as drought stress intensifies under climate change, yet this topic is not fully understood. Currently, conclusions on the response of ecosystems in different regions to drought disturbance are inconsistent. Based on long MODIS data and observed data, this study systematically explored the relationships between ecosystem patterns, structures and functions and drought, taking a typical climate change-sensitive area and an ecologically fragile area-the Yellow River Basin-as a case study. Drought assessment results revealed that the Yellow River Basin has experienced meteorological and hydrological drought during most of the last two decades, predominantly characterized by medium and slight droughts. The ecosystem patterns and structures changed dramatically as the grassland decreased and the landscape fragmentation index (F) increased with increasing wetness. The annual gross primary productivity (GPP) increased, the water use efficiency (WUE) declined and ecosystem service value (ESV) exhibited a W-shaped increase at the watershed scale, but there were significant regional differences. There were positive correlations between F, GPP, ESV and drought indices, while there was a negative correlation between WUE and drought indices at the watershed scale. Under drought stress, the ecosystem structure in the basin was disrupted, the GPP and ESV decreased, but the WUE increased. Notably, approximately 106 %, 20 %, and 1 % of the maximum reductions in F, GPP, and ESV, respectively, were caused by drought, while the maximum 4 % of WUE increased. Responses of some functions in the wetland and grassland to drought vary from those in other ecosystems. The mechanisms underlying ecosystem responses to drought were further investigated. This study enhances the understanding of these responses and will help stakeholders formulate drought mitigation policies and protect ecosystem health.

Mitigation of drought stress in maize and sorghum by humic acid: differential growth and physiological responses

BACKGROUND

Drought is a major determinant for growth and productivity of all crops, including cereals, and the drought-induced detrimental effects are anticipated to jeopardize world food security under the ongoing global warming scenario. Biostimulants such as humic acid (HA) can improve drought tolerance in many cereals, including maize and sorghum. These two plant species are genetically related; however, maize is more susceptible to drought than sorghum. The physiological and biochemical mechanisms underlying such differential responses to water shortage in the absence and presence of HA, particularly under field conditions, are not fully understood.

RESULTS

Herein, the effects of priming maize and sorghum seeds in 100 mg L-1 HA on their vegetative growth and physiological responses under increased levels of drought (100%, 80%, and 60% field capacity) were simultaneously monitored in the field. In the absence of HA, drought caused 37.0 and 58.7% reductions in biomass accumulation in maize compared to 21.2 and 32.3% in sorghum under low and high drought levels, respectively. These responses were associated with differential retardation in overall growth, relative water content (RWC), photosynthetic pigments and CO2 assimilation in both plants. In contrast, drought increased root traits as well as H2O2, malondialdehyde, and electrolyte leakage in both species. HA treatment significantly improved the growth of both plant species under well-watered and drought conditions, with maize being more responsive than sorghum. HA induced a 29.2% increase in the photosynthetic assimilation rate in maize compared to 15.0% in sorghum under high drought level. The HA-promotive effects were also associated with higher total chlorophyll, stomatal conductance, RWC, sucrose, total soluble sugars, total carbohydrates, proline, and total soluble proteins. HA also reduced the drought-induced oxidative stress via induction of non-enzymic and enzymic antioxidants at significantly different extents in maize and sorghum.

CONCLUSION

The current results identify significant quantitative differences in a set of critical physiological biomarkers underlying the differential responses of field-grown maize and sorghum plants against drought. They also reveal the potential of HA priming as a drought-alleviating biostimulant and as an effective approach for sustainable maize and sorghum production and possibly other crops in drought-affected lands.

Assessment of Various Nanoprimings for Boosting Pea Germination and Early Growth in Both Optimal and Drought-Stressed Environments

One of the main climate change-related variables limiting agricultural productivity that ultimately leads to food insecurity appears to be drought. With the use of a recently discovered nanopriming technology, seeds can endure various abiotic challenges. To improve seed quality and initial growth of 8-day-old field pea seedlings (cv. NS Junior) under optimal and artificial drought (PEG-induced) laboratory conditions, this study aimed to assess the efficacy of priming with three different nanomaterials: Nanoplant Ultra (Co, Mn, Cu, Fe, Zn, Mo, and Se), Nanoplant Ca-Si (Ca, Si, B, and Fe), and Nanoplant Sulfur (S). The findings indicate that nanopriming seed treatments have a positive impact on seed quality indicators, early plant growth, and drought resilience in field pea plants established in both optimal and drought-stressed conditions. Nevertheless, all treatments showed a positive effect, but their modes of action varied. Nanoplant Ultra proved to be the most effective under optimal conditions, whereas Nanoplant Ca-Si and Nanoplant Sulfur were the most efficient under drought stress. After a field evaluation, the examined comprehensive nanomaterials may be utilized as priming agents for pea seed priming to boost seed germination, initial plant growth, and crop productivity under various environmental conditions.

Bioprospecting the roles of Trichoderma in alleviating plants' drought tolerance: Principles, mechanisms of action, and prospects

Drought-induced stress represents a significant challenge to agricultural production, exerting adverse effects on both plant growth and overall productivity. Therefore, the exploration of innovative long-term approaches for addressing drought stress within agriculture constitutes a crucial objective, given its vital role in enhancing food security. This article explores the potential use of Trichoderma, a well-known genus of plant growth-promoting fungi, to enhance plant tolerance to drought stress. Trichoderma species have shown remarkable potential for enhancing plant growth, inducing systemic resistance, and ameliorating the adverse impacts of drought stress on plants through the modulation of morphological, physiological, biochemical, and molecular characteristics. In conclusion, the exploitation of Trichoderma's potential as a sustainable solution to enhance plant drought tolerance is a promising avenue for addressing the challenges posed by the changing climate. The manifold advantages of Trichoderma in promoting plant growth and alleviating the effects of drought stress underscore their pivotal role in fostering sustainable agricultural practices and enhancing food security.

Salicylic acid and Tocopherol improve wheat (Triticum aestivum L.) Physio-biochemical and agronomic features grown in deep sowing stress: a way forward towards sustainable production

BACKGROUND

The rate of germination and other physiological characteristics of seeds that are germinating are impacted by deep sowing. Based on the results of earlier studies, conclusions were drawn that deep sowing altered the physio-biochemical and agronomic characteristics of wheat (Triticum aestivum L.).

RESULTS

In this study, seeds of wheat were sown at 2 (control) and 6 cm depth and the impact of exogenously applied salicylic acid and tocopherol (Vitamin-E) on its physio-biochemical and agronomic features was assessed. As a result, seeds grown at 2 cm depth witnessed an increase in mean germination time, germination percentage, germination rate index, germination energy, and seed vigor index. In contrast, 6 cm deep sowing resulted in negatively affecting all the aforementioned agronomic characteristics. In addition, deep planting led to a rise in MDA, glutathione reductase, and antioxidants enzymes including APX, POD, and SOD concentration. Moreover, the concentration of chlorophyll a, b, carotenoids, proline, protein, sugar, hydrogen peroxide, and agronomic attributes was boosted significantly with exogenously applied salicylic acid and tocopherol under deep sowing stress.

CONCLUSIONS

The results of the study showed that the depth of seed sowing has an impact on agronomic and physio-biochemical characteristics and that the negative effects of deep sowing stress can be reduced by applying salicylic acid and tocopherol to the leaves.

Unveiling Fungi Armor: Preliminary Study on Fortifying Pisum sativum L. Seeds against Drought with Schizophyllum commune Fries 1815 Polysaccharide Fractions

Amidst worsening climate change, drought stress imperils global agriculture, jeopardizing crop yields and food security, thereby necessitating the urgent exploration of sustainable methods like biopriming for the harnessing of beneficial microorganisms to bolster plant resilience. Recent research has revealed diverse biological compounds with versatile applications produced by Schizophyllum commune, rendering this fungus as a promising contender for biopriming applications. For the first time, this study aimed to investigate the potential of S. commune exo- (EPSH) and intra-polysaccharides (IPSH) isolated from two strains-Italian (ITA) and Serbian (SRB)-under submerged cultivation to enhance the resilience of Pisum sativum L. seeds through the biopriming technique. Testing of the seed quality for the bioprimed, hydroprimed, and unprimed seeds was conducted using a germination test, under optimal and drought conditions, while characterization of the PSHs included FTIR analysis, microanalysis, and determination of total protein content (TPC). The FTIR spectra of EPSH and IPSH were very similar but revealed the impurities, while microanalysis and TPC confirmed a different presence of proteins in the isolated PSHs. In optimal conditions, the IPSH SRB increased germination energy by 5.50% compared to the control; however, the highest percentage of germination (94.70%) was shown after biopriming with the PSH isolated from the ITA strain. Additionally, all assessed treatments resulted in a boost in seedling growth and biomass accumulation, where the ITA strain demonstrated greater effectiveness in optimal conditions, while the SRB strain showed superiority in drought conditions. The drought tolerance indices increased significantly in response to all examined treatments during the drought, with EPSH ITA (23.00%) and EPSH SRB (24.00%) demonstrating the greatest effects. Results of this preliminary study demonstrate the positive effect of isolated PSH, indicating their potential as biopriming agents and offering insights into novel strategies for agricultural resilience.

Sodium nitroprusside modulates oxidative and nitrosative processes in Lycopersicum esculentum L. under drought stress

KEY MESSAGE

Sodium nitroprusside mediates drought stress responses in tomatoes by modulating nitrosative and oxidative pathways, highlighting the interplay between nitric oxide, hydrogen sulfide, and antioxidant systems for enhanced drought tolerance. While nitric oxide (NO), a signalling molecule, enhances plant tolerance to abiotic stresses, its precise contribution to improving tomato tolerance to drought stress (DS) through modulating oxide-nitrosative processes is not yet fully understood. We aimed to examine the interaction of NO and nitrosative signaling, revealing how sodium nitroprusside (SNP) could mitigate the effects of DS on tomatoes. DS-seedlings endured 12% polyethylene glycol (PEG) in a 10% nutrient solution (NS) for 2 days, then transitioned to half-strength NS for 10 days alongside control plants. DS reduced total plant dry weight, chlorophyll a and b, Fv/Fm, leaf water potential (ΨI), and relative water content, but improved hydrogen peroxide (H2O2), proline, and NO content. The SNP reduced the DS-induced H2O2 generation by reducing thiol (-SH) and the carbonyl (-CO) groups. SNP increased not only NO but also the activity of L-cysteine desulfhydrase (L-DES), leading to the generation of H2S. Decreases in S-nitrosoglutathione reductase (GSNOR) and NADPH oxidase (NOX) suggest a potential regulatory mechanism in which S-nitrosylation [formation of S-nitrosothiol (SNO)] may influence protein function and signaling pathways during DS. Moreover, SNP improved ascorbate (AsA) and glutathione (GSH) and reduced oxidized glutathione (GSSG) levels in tomato plants under drought. Furthermore, the interaction of NO and H2S, mediated by L-DES activity, may serve as a vital cross-talk mechanism impacting plant responses to DS. Understanding these signaling interactions is crucial for developing innovative drought-tolerance strategies in crops.