Alleviate Drought Stress Research Articles

Salicylic Acid with Humic Acid Addition as Potential Hallmarks for Alleviating Drought Stress in Maize Crop and Enhancing Soil Health

Climate change is the biggest concern to the human kind and threat to agri-food security. Deficiency of water in soil and the ability of plants to uptake water is slowed down due rising temperature and microbial imbalance in soil. Salicylic acid plays an important role in mitigating drought stress and improves the overall production of crop. Humic acid is another amendment to cope against water stress and optimizes the yield. Apart from that, there is little known about their impact on soil geochemistry and that how soil health is altered.
 To investigate the effect of salicylic acid and humic acid on the drought experiment was conducted at University Research Farm (URF), PMAS Arid Agriculture University, Rawalpindi during summer 2023. The experiment was set up in randomized complete block design in two factorial arrangements with four replications. The first factor was comprised of mitigation strategies; salicylic acid, humic acid and chemical fertilizer, while second factor was water regimes; water stress and irrigation maintaining 60% field capacity.
 Plant attributes including chlorophyll content (SPAD value), total soluble protein content (mg/g), total free amino acid (mg/g), K+ content (mg/g), Na+ content (mg/g), 1000 grain weight (g) and grain yield (kg/ha) were measured and reported. On the other hand, soil parameters that were estimated are: soil pH, soil organic matter content (%), available N (ppm), available P (ppm), available K (ppm) and cation exchange capacity (cmol/kg).
 According to the data analysis, all of the features under study had a substantial impact from the mitigation approaches. The increased value of chlorophyll content (49.11 mg/g) was obtained in water stressed condition by the application of salicylic acid. Under water stressed regime and salicylic acid boosted the total soluble protein content (1.67 mg/g) and total free amino acid (31.93 mg/g) while grain yield (9451.7 kg/ha) was also boosted up by the amendment salicylic acid in maize. There was also increase in the values of soil pH (6.78), CEC (54.37 cmol/kg), SOM content (0.87%), available N (3.24 ppm), available P (26.14 ppm) and available K (211.23 ppm) drought conditions with the implementation of salicylic acid.
 Humic acid also positively impacted the drought stress and improved the maize yield (8436.2 kg/ha) under drought condition. Similarly, soil nutrient retention is also improved to large extent under water stress state; SOM content (0.49%), available N (2.36 ppm), available P (15.67 ppm) and available K (171.94 ppm).
 Overall, the study showed that amendment of salicylic acid and humic acid, is the greatest strategy to increase crop production and quality while also improving the health of the soil.

Co-application of Chitosan and Ascorbic Acid Alleviated Drought Stress in Common Chicory (Cichorium Intybus L.) by Improving Physiological and Biochemical Changes

Co-application of Chitosan and Ascorbic Acid Alleviated Drought Stress in Common Chicory (Cichorium Intybus L.) by Improving Physiological and Biochemical Changes

Transcriptomic and metabolomic profiling reveals the drought tolerance mechanism of Illicium difengpi (Schisandraceae).

Illicium difengpi (Schisandraceae), an endangered medicinal plant endemic to karst areas, is highly tolerant to drought and thus can be used as an ideal material for investigating adaptive mechanism to drought stress. The understanding of the drought tolerance of I. difengpi, especially at the molecular level, is lacking. In the present study, we aimed to clarify the molecular mechanism underlying drought tolerance in endemic I. difengpi plant in karst regions. The response characteristics of transcripts and changes in metabolite abundance of I. difengpi subjected to drought and rehydration were analyzed, the genes and key metabolites responsive to drought and rehydration were screened, and some important biosynthetic and secondary metabolic pathways were identified. A total of 231,784 genes and 632 metabolites were obtained from transcriptome and metabolome analyses, and most of the physiological metabolism in drought-treated I. difengpi plants recovered after rehydration. There were more upregulated genes than downregulated genes under drought and rehydration treatments, and rehydration treatment induced stable expression of 65.25% of genes, indicating that rehydration alleviated drought stress to some extent. Drought and rehydration treatment generated flavonoids, phenolic acids, flavonols, amino acids and their derivatives, as well as metabolites such as saccharides and alcohols in the leaves of I. difengpi plants, which alleviated the injury caused by excessive reactive oxygen species. The integration of transcriptome and metabolome analyses showed that, under drought stress, I. difengpi increased glutathione, flavonoids, polyamines, soluble sugars and amino acids, contributing to cell osmotic potential and antioxidant activity. The results show that the high drought tolerance and recovery after rehydration are the reasons for the normal growth of I. difengpi in karst mountain areas.

Drought reduces productivity and anti-herbivore defences, but not mycorrhizal associations, of perennial prairie forbs.

During drought, plants allocate resources to aboveground biomass production and belowground carbohydrate reserves, often at the expense of production of defence traits. Additionally, drought has been shown to alter floral resources, with potential implications for plant-pollinator interactions. Although soil symbionts, such as arbuscular mycorrhizal (AM) fungi, can alleviate drought stress in plants, certain levels of drought may negatively impact this relationship, with potential cascading effects. Because of their importance to plant and animal community diversity, we examined effects of drought on biomass production, physical defence properties, nectar production, and associated AM fungal abundance of five common prairie forb species in a greenhouse study. Reduced soil moisture decreased vegetative biomass production. Production of trichomes and latex decreased under drought, relative to well-watered conditions. Ruellia humilis flowers produced less nectar under drought, relative to well-watered conditions. Intra-radical AM fungal colonization was not significantly affected by drought, although extra-radical AM fungal biomass associated with S. azurea decreased following drought. Overall, grassland forb productivity, defence, and nectar production were negatively impacted by moderate drought, with possible negative implications for biotic interactions. Reduced flower and nectar production may lead to fewer pollinator visitors, which may contribute to seed limitation in forb species. Reduced physical defences increase the likelihood of herbivory, further decreasing the ability to store energy for essential functions, such as reproduction. Together, these results suggest drought can potentially impact biotic interactions between plants and herbivores, pollinators, and soil symbionts, and highlights the need for direct assessments of these relationships under climate change scenarios.

Composts of diverse green wastes improve the soil biological quality, but do not alleviate drought impact on lettuce (Lactuca sativa L.) growth

AbstractIntense soil cultivation and climate change have detrimental effects on soils. Solutions are needed to improve the biological quality and water holding capacity of agricultural soils. A greenhouse experiment was conducted to investigate the interactive effect of compost application and drought stress on a soil/plant system in order to determine the improvement of soil quality and plant growth and the alleviation of drought stress. Lettuce (Lactuca sativa L.) was grown under greenhouse conditions in a sandy soil with sufficient mineral fertilizer application to test the effect of five compost types (three made from municipal garden and park wastes with differing nutrient contents, one from municipal household waste, and one from farm plant residues) applied at 30 Mg ha−1 dry weight, with which we compared soil quality and plant growth to soil without compost application. Treatment pots were irrigated or subjected to drought conditions during the last 14 days of lettuce growth. Assays of potential N mineralization during 28 days, dehydrogenase and β‐glucosidase activities, and a phospholipid fatty acid (PLFA) analysis were performed to assess effects on soil biological quality. Gas exchange, leaf relative water content, biomass, nitrogen accumulation, and root tip growth of lettuce were measured to investigate compost and drought stress effects on lettuce physiology. All composts improved indices of soil biological quality significantly, except for fungal abundance, relative to soil without compost. The greatest increase was obtained from farm compost, which significantly increased potential nitrogen (N) mineralization and soil enzyme activities of β‐glucosidase and dehydrogenase by factors of 4, 2, and 43, respectively. Furthermore, soil with farm compost generally showed a higher abundance of soil microbial organisms compared with soil without compost, which could be related to its high cellulose and hemicellulose contents. The lowest abundance of microbial organisms was generally found in soil with garden and park waste compost with a medium nutrient content, which could be related to its low organic matter content. The beneficial effect of compost on soil biological quality did not lead to improved lettuce growth, which suggests that soil biological quality (ameliorated by compost application) is not important for a fast‐growing crop, such as lettuce, that is sufficiently fertilized. Drought stress reduced aboveground lettuce biomass, root tip growth, and the abundance of most soil microbial groups significantly, but compost in soil did not alleviate these negative effects. In conclusion, the farm compost made from grass–clover, straw, and vegetable residues is superior to garden and park waste and household waste composts in terms of beneficial effects on soil biological quality. Compost clearly improved soil biological quality, but did not influence lettuce's response to drought stress. The knowledge gained in this study is useful for producing tailor‐made compost with desired effects of improved soil biological quality.

Overview of insights into the role of Bacillus species in drought stress alleviation and plant disease management

Drought and plant diseases are major constraints on crop production, causing significant losses. As the effects of climate change worsen, there is an urgent need to adopt sustainable agricultural strategies. Plant Growth-Promoting Bacteria (PGPB) are emerging as a promising approach, aimed at enhancing productivity and plant resilience to various stresses. Among them, Bacillus spp. are gaining research interest due to their unique ability to adapt to harsh environmental conditions and produce metabolites of interest in several sectors. Besides improving plant growth and yield, Bacillus plays a pivotal role in enhancing the ability of plants to withstand drought stress mainly by producing of water absorbing substances and enhancing water and nutrient uptake. Some Bacillus species are able to effectively resist plant pathogens through several mechanisms, including antibiosis, competition, induced systemic resistance (ISR), and enriching the microbiome of the soil, enabling them to become important biological agents in the management of plant diseases. This overview aims to highlight the potential of Bacillus species in sustainable agriculture, focusing on their role in mitigating drought stress and controlling plant diseases.

Physiological Insights of Melatonin Hormone for Alleviation of Drought Stress in Rice

Drought stress significantly hampers crop growth and yield by negatively impacting various biochemical and physiological plant processes. This study aimed to assess drought tolerance in traditional rice varieties using Poly Ethylene Glycol 6000 (PEG 6000) and focused on the effectiveness of melatonin applied through both seed treatment and foliar spray in mitigating the effects of drought stress. The optimal drought screening conditions were determined at a PEG concentration of -4 bars. As the PEG concentration increased, key factors such as germination percentage, vigor index, root length, and shoot length decreased. This indicates that PEG can be a useful tool for early selection of drought tolerant rice varieties. Melatonin (N-acetyl-5-methoxytryptamine), known for alleviating abiotic stress, showed positive effects on seed germination at 200 ppm concentration. The study observed that stomatal closure is a natural response to drought stress, but melatonin application induced partial stomatal opening. Notably, a foliar spray of 100 ppm melatonin demonstrated better recovery from drought stress compared to the 200 ppm concentration. In conclusion, the research suggests that seed treatment with 200 ppm melatonin and foliar spraying with 100 ppm melatonin are the most effective approaches for reducing the adverse effects of drought stress in rice plants.

Seed Priming with Nano Silica Alleviates Drought Stress through Regulating Antioxidant Defense System and Osmotic Adjustment in Soybean (Glycine max L.)

Seed Priming with Nano Silica Alleviates Drought Stress through Regulating Antioxidant Defense System and Osmotic Adjustment in Soybean (Glycine max L.)

The use of hydrogel reduces water stress and improves yield in the cultivation of purple corn

One of the problems in agriculture today is the scarcity of water available for crops. The aim of the research was to evaluate the use of a hydrogel (plantagel with a composition of 96% non-toxic potassium polyacrylate) in the water stress of the PMV-581 purple corn crop and evaluate its development and performance. The treatments were at three doses of 50, 70, 90 kg ha-1 of hydrogel (plantagel) and a control without hydrogel application, the results indicate the T0 control treatment. Treatment T1 (with 12 irrigations and 50 kg ha-1 of hydrogel) and T2 (with 10 irrigations and 70 kg ha-1 of hydrogel) require the greatest number of irrigations (with 15 irrigations and without hydrogel application) and T3 (with 8 irrigations and 90 kg ha-1 of hydrogel) T3 obtained the highest yield of 6.50 t ha-1, with a water table of 1500.84 m3, lower than the rest of the treatments, concluding that the Hydrogel influences soil moisture retention and its effect is expressed in the yield of purple corn. These results provide valuable information that the use of hydrogel (plantagel) could be effectively applied as a soil additive to alleviate drought stress in purple corn cultivation.

Ability of nitrogen-fixing bacteria to alleviate drought stress in cowpea varies depending on the origin of the inoculated strain

Ability of nitrogen-fixing bacteria to alleviate drought stress in cowpea varies depending on the origin of the inoculated strain

Elevated CO2 concentration enhances drought resistance of soybean by regulating cell structure, cuticular wax synthesis, photosynthesis, and oxidative stress response

The atmospheric [CO2] and the frequency and intensity of extreme weather events such as drought are increased, leading to uncertainty to soybean production. Elevated [CO2] (eCO2) partially mitigates the adverse effects of drought stress on crop growth and photosynthetic performance, but the mitigative mechanism is not well understood. In this study, soybean seedlings under drought stress simulated by PEG-6000 were grown in climate chambers with different [CO2] (400 μmol mol−1 and 700 μmol mol−1). The changes in anatomical structure, wax content, photosynthesis, and antioxidant enzyme were investigated by the analysis of physiology and transcriptome sequencing (RNA-seq). The results showed that eCO2 increased the thickness of mesophyll cells and decreased the thickness of epidermal cells accompanied by reduced stomatal conductance, thus reducing water loss in soybean grown under drought stress. Meanwhile, eCO2 up-regulated genes related to wax anabolism, thus producing more epidermal wax. Under drought stress, eCO2 increased net photosynthetic rate (PN), ribulose-1,5-bisphosphate carboxylase/oxygenase activity, and alerted the gene expressions in photosynthesis. The increased sucrose synthesis and decreased sucrose decomposition contributed to the progressive increase in the soluble saccharide contents under drought stress with or without eCO2. In addition, eCO2 increased the expressions of genes associated with peroxidase (POD) and proline (Pro), thus enhancing POD activity and Pro content and improving the drought resistance in soybean. Taken together, these findings deepen our understanding of the effects of eCO2 on alleviating drought stress in soybean and provide potential target genes for the genetic improvement of drought tolerance in soybean.

Efficacious role of silica nanoparticles in improving growth and yield of wheat under drought stress through stress-gene upregulation

Climate change is now evident and severe water shortage due to unpredictable raining season along with extended summers is expected to hamper crop production across the globe. Application of nanoparticle based formulations is one of the most sought after approach that is being explored currently to alleviate drought stress impact on plants. The present study was aimed to evaluate the potential of biosynthesized silica nanoparticles (silica NPs) in improving the drought tolerance of wheat. Four different concentrations of silica NPs (30, 60, 90, and 120 ppm) were used to treat wheat plants grown under two irrigation regimes- 50% soil moisture content (drought) and 100% soil moisture content (well-watered). The induced drought caused a prominent reduction in both - the crop yield and the morphological parameters of the crop. Foliar application of silica NPs at all concentrations, increased the plant's tolerance towards water stress but 60 ppm concentration was found to be most effective amongst all. After treatment with silica NPs at 60 ppm concentration, the plant height increased by 8.28%, spikes per plant by 98%, seeds per spike by 12.4%, and thousand seed weight by 37.5% as compared to the control. Besides this, expression levels of four drought-stress responsive genes-ABC1, Wdhn13, CHP, and EXP2 was also studied. We observed an enhanced expression of all the stress genes after treatment with silica nanoparticles in wheat plants grown under water deficient conditions, clearly supporting the influence of NP treatment at gene/molecular level. In nutshell, we conclude that silica nanoparticles have the potential to significantly ameliorate the negative impact of drought stress by reviving plant growth and modulating gene expression.

Combination of seed priming and nutrient foliar application improved physiological attributes, grain yield, and biofortification of rainfed wheat.

Seed priming and foliar application are two crop management practices that can increase grain yield and quality. The research aimed to assess the influence of seed priming and foliar application on rainfed wheat. Two field experiments with two seed priming rates (control and priming) and five foliar applications [control, urea (4%), silicon (4 mM), FeSO4.7H2O (0.6%), and ZnSO4.7H2O (0.4%)] at the anthesis/Z61 stage were conducted. Seeds were primed for 12h at 25 ± 2°C, by soaking in an aerating solution [urea (20g L-1) + FeSO4.7H2O (50 ppm) + ZnSO4.7H2O (50 ppm) + silicon (20 mg L-1)]. Seed weight-to-solution volume ratio was 1:5 (kg L-1). A pot experiment was also conducted to examine the effect of priming on root growth. Overall, combined seed priming and foliar application induced a positive impact on physiological traits and attributes. Maximum chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid concentrations (1.58, 0.669, 2.24, and 0.61 mg g-1 FW), membrane stability index (77.31%), superoxide dismutase and peroxidase activity (0.174 and 0.375 Unit mg-1 protein), 1,000-grain weight (35.30g), biological yield, grain yield (8,061 and 2,456 kg ha-1), and minimum malondialdehyde concentration (3.91 µg g-1 FW) were observed in seed priming combination with ZnSO4 foliar application. The highest glycine betaine concentration (6.90 mg g-1 DW) and proline (972.8 µg g-1 FW) were recorded with the co-application of seed priming and foliar urea spraying. Foliar application of ZnSO4, FeSO4, and urea drastically enhanced grain Zn (29.17%), Fe (19.51%), and protein content (increased from 11.14% in control to 12.46% in urea foliar application), respectively. Compared to control, seed priming increased root length, root volume, and dry mass root by 8.95%, 4.31%, and 9.64%, respectively. It is concluded that adequate Zn, Fe, silicon, and N supply through seed priming and foliar applications of these compounds at the terminal stage of rainfed wheat alleviates drought stress and improves GY and biofortification.

Seed priming of pepper (Capsicum annuum L.) with β-aminobutyric acid (BABA) alleviates drought stress

Seed priming of pepper (Capsicum annuum L.) with β-aminobutyric acid (BABA) alleviates drought stress

Alleviation of cadmium and drought stress in wheat by improving growth and chlorophyll contents amended with GA3 enriched deashed biochar

Drought and cadmium (Cd) stress are both major issues that significantly affect the growth and development of wheat plants. Both drought stress and Cd toxicity disrupt physiological processes i.e., nutrient uptake, cell expansion, and enzymatic reactions resulting in poor crop growth. To overcome these issues, the use of activated carbon and gibberellic acid (GA3) are considered valuable amendments. However, the current study aimed to add value using GA3-enriched biochar (GA3-BC). That’s why, a lab experiment was conducted on wheat to assess the effectiveness of GA3-BC against Cd and drought stress. For GA3 enrichment in biochar, 10 µg GA3/g biochar was mixed. There were 3 levels of GA3-BC i.e., 0, 0.6 (GA3-BC1), and 0.9% (GA3-BC). All levels were applied in 3 replicates under no stress (0Cd + no drought), drought stress (DS), and 6 mg Cd/ kg soil (6Cd). Results showed that GA3-BC2 caused a significant improvement in shoot length (44.99%), root length (99.73%), seedling length (60.13%) and shoot fresh weight (63.59%) over control at 6Cd + drought stress. A significant improvement in chlorophyll a, chlorophyll b, and total chlorophyll while a decrease in electrolyte leakage and regulation of antioxidants i.e., lipid peroxidation, SOD, CAT, APx, GR, GPx, GST, and DPHH also signified the effectiveness of GA3-BC2 compared to control at 6Cd + drought stress. In conclusion, GA3-BC2 is an efficacious amendment for simultaneously alleviating drought and Cd stress in wheat. More investigations are recommended at the field level on different cereal crops cultivated in different soil textures to declare GA3-BC2 as the best treatment for mitigation of drought stress and Cd toxicity.

Physiological and RNA-Seq Analyses on Exogenous Strigolactones Alleviating Drought by Improving Antioxidation and Photosynthesis in Wheat (Triticum aestivum L.).

Drought poses a significant challenge to global wheat production, and the application of exogenous phytohormones offers a convenient approach to enhancing drought tolerance of wheat. However, little is known about the molecular mechanism by which strigolactones (SLs), newly discovered phytohormones, alleviate drought stress in wheat. Therefore, this study is aimed at elucidating the physiological and molecular mechanisms operating in wheat and gaining insights into the specific role of SLs in ameliorating responses to the stress. The results showed that SLs application upregulated the expression of genes associated with the antioxidant defense system (Fe/Mn-SOD, PER1, PER22, SPC4, CAT2, APX1, APX7, GSTU6, GST4, GOR, GRXC1, and GRXC15), chlorophyll biogenesis (CHLH, and CPX), light-harvesting chlorophyll A-B binding proteins (WHAB1.6, and LHC Ib-21), electron transfer (PNSL2), E3 ubiquitin-protein ligase (BB, CHIP, and RHY1A), heat stress transcription factor (HSFA1, HSFA4D, and HSFC2B), heat shock proteins (HSP23.2, HSP16.9A, HSP17.9A, HSP21, HSP70, HSP70-16, HSP70-17, HSP70-8, HSP90-5, and HSP90-6), DnaJ family members (ATJ1, ATJ3, and DJA6), as well as other chaperones (BAG1, CIP73, CIPB1, and CPN60I). but the expression level of genes involved in chlorophyll degradation (SGR, NOL, PPH, PAO, TIC55, and PTC52) as well as photorespiration (AGT2) was found to be downregulated by SLs priming. As a result, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced, and chlorophyll content and photosynthetic rate were increased, which indicated the alleviation of drought stress in wheat. These findings demonstrated that SLs alleviate drought stress by promoting photosynthesis through enhancing chlorophyll levels, and by facilitating ROS scavenging through modulation of the antioxidant system. The study advances understandings of the molecular mechanism underlying SLs-mediated drought alleviation and provides valuable insights for implementing sustainable farming practice under water restriction.

Combined biochar and water-retaining agent application increased soil water retention capacity and maize seedling drought resistance in Fluvisols

Global climate change has accelerated the occurrence of agricultural drought events, which threaten food security. Therefore, improvements in the soil water retention capacity (WRC) and crop drought resistance are crucial for promoting the sustainability of the agricultural environment. In this study, we explored the effects of applying biochar and water-retaining agent (WRA) on soil WRC and crop drought resistance in a Fluvisols, along with their potential mechanisms. We applied two types of biochar (based on wheat and maize straw) and two WRAs (polyacrylamide and starch-grafted sodium acrylate) to Fluvisols with different textures, and then evaluated soil water retention and crop drought physiological resistance. The combined biochar and WRA treatment increased the WRC in both the sandy loam and clay loam Fluvisols. Biochar and WRA increased the relative content of soil hydrophilic functional groups. Compared with the control (CK), the combined application of biochar and WRA increased the field capacity, reduced soil water volatilization under drought conditions, and slowed water infiltration into the Fluvisols. The soil WRC was higher with the wheat straw biochar (WBC) treatment than with the maize straw biochar (MBC) treatment. It was also higher with polyacrylamide treatment than with the starch-grafted sodium acrylate treatment. The combined application of biochar and WRA improved crop drought physiological resistance by significantly increasing the maize seedling potassium (K) and soluble sugar contents, increasing antioxidant enzyme activity, and reducing the malondialdehyde (MDA) content. The results indicate that the application of biochar and WRA alleviated drought stress by increasing the soil WRC and improving crop drought resistance in Fluvisols.

Physiological and Biochemical Effects of Exogenous Calcium on Camellia oleifera Abel under Drought Stress

High temperature and drought are the main factors restricting the increase in Camellia oleifera Abel production that can seriously harm its physiological and biochemical functions. This study aimed to explore the effect by which Ca2+ enhances the drought resistance of C. oleifera. Four-year-old potted plants of the ‘Xianglin 210’ variety were treated with four levels of CaCl2 solution (0, 10, 20, and 40 mmol/L) and subjected to natural drought stress. The drought levels were categorized as CS (non-drought), LD (light drought), MD (moderate drought), and SD (severe drought). The effects of drought stress on the growth and physiological-biochemical characteristics of C. oleifera were measured. Under drought stress, spraying CaCl2 solution on leaves could significantly increase the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), endogenous hormone indoleacetic acid (IAA) content, abscisic acid (ABA) content, and gibberellic acid (GA) content in organs and tissues; enhance the superoxide dismutase (SOD) activity; and decrease the concentration of intercellular carbon dioxide (Ci) and number of dehiscence fruits. Spraying 10 mmol/L CaCl2 effectively alleviates the damage of drought stress to tung oil trees. The study provides references for alleviating drought stress and increasing economic benefits in C. oleifera production.

Novel insights into the mechanism(s) of silicon-induced drought stress tolerance in lentil plants revealed by RNA sequencing analysis

BackgroundLentil is an essential cool-season food legume that offers several benefits in human nutrition and cropping systems. Drought stress is the major environmental constraint affecting lentil plants’ growth and productivity by altering various morphological, physiological, and biochemical traits. Our previous research provided physiological and biochemical evidence showing the role of silicon (Si) in alleviating drought stress in lentil plants, while the molecular mechanisms are still unidentified. Understanding the molecular mechanisms of Si-mediated drought stress tolerance can provide fundamental information to enhance our knowledge of essential gene functions and pathways modulated by Si during drought stress in plants. Thus, the present study compared the transcriptomic characteristics of two lentil genotypes (drought tolerant-ILL6002; drought sensitive-ILL7537) under drought stress and investigated the gene expression in response to Si supplementation using high-throughput RNA sequencing.ResultsThis study identified 7164 and 5576 differentially expressed genes (DEGs) from drought-stressed lentil genotypes (ILL 6002 and ILL 7537, respectively), with Si treatment. RNA sequencing results showed that Si supplementation could alter the expression of genes related to photosynthesis, osmoprotection, antioxidant systems and signal transduction in both genotypes under drought stress. Furthermore, these DEGs from both genotypes were found to be associated with the metabolism of carbohydrates, lipids and proteins. The identified DEGs were also linked to cell wall biosynthesis and vasculature development. Results suggested that Si modulated the dynamics of biosynthesis of alkaloids and flavonoids and their metabolism in drought-stressed lentil genotypes. Drought-recovery-related DEGs identified from both genotypes validated the role of Si as a drought stress alleviator. This study identified different possible defense-related responses mediated by Si in response to drought stress in lentil plants including cellular redox homeostasis by reactive oxygen species (ROS), cell wall reinforcement by the deposition of cellulose, lignin, xyloglucan, chitin and xylan, secondary metabolites production, osmotic adjustment and stomatal closure.ConclusionOverall, the results suggested that a coordinated interplay between various metabolic pathways is required for Si to induce drought tolerance. This study identified potential genes and different defence mechanisms involved in Si-induced drought stress tolerance in lentil plants. Si supplementation altered various metabolic functions like photosynthesis, antioxidant defence system, osmotic balance, hormonal biosynthesis, signalling, amino acid biosynthesis and metabolism of carbohydrates and lipids under drought stress. These novel findings validated the role of Si in drought stress mitigation and have also provided an opportunity to enhance our understanding at the genomic level of Si’s role in alleviating drought stress in plants.

Exogenous strigolactones alleviate drought stress in wheat (Triticum aestivum L.) by promoting cell wall biogenesis to optimize root architecture

Exogenous strigolactones (SLs, GR24) are widely used to alleviate drought stress in wheat. The physiological and biochemical mechanisms via which SLs help overcome drought stress in wheat shoots have been reported; however, the mechanisms in wheat roots are unclear. The present study explored the effects of the exogenous application of SLs on wheat roots’ growth and molecular responses under drought stress using physiological analysis and RNA-seq. RNA-seq of roots showed that SLs mainly upregulated signal transduction genes (SIS8, CBL3, GLR2.8, LRK10L-2.4, CRK29, and CRK8) and transcription factors genes (ABR1, BHLH61, and MYB93). Besides, SLs upregulated a few downstream target genes, including antioxidant genes (PER2, GSTF1, and GSTU6), cell wall biogenesis genes (SUS4, ADF3, UGT13248, UGT85A24, UGT709G2, BGLU31, and LAC5), an aquaporin-encoding gene (TIP4-3), and dehydrin-encoding genes (DHN2, DHN3, and DHN4). As a result, SLs reduced oxidative damage, optimized root architecture, improved leaf-water relation, and alleviated drought damage. Thus, the present study provides novel insights into GR24-mediated drought stress management and a scientific basis for proposing GR24 application.