Drought Stress Conditions Research Articles

Genome-wide identification and characterization of FORMIN gene family in potato (Solanum tuberosum L.) and their expression profiles in response to drought stress condition.

Formin proteins, characterized by the FH2 domain, are critical in regulating actin-driven cellular processes and cytoskeletal dynamics during abiotic stress. However, no genome-wide analysis of the formin gene family has yet to be conducted in the economically significant plant potato (Solanum tuberosum L.). In this study, 26 formin genes were identified and characterized in the potato genome (named as StFH), each containing the typical FH2 domain and distributed across the ten chromosomes. The StFH was categorized into seven subgroups (A-G) and the gene structure and motif analysis demonstrated higher structural similarities within the subgroups. Besides, the StFH exhibited ancestry and functional similarities with Arabidopsis. The Ka/Ks ratio indicated that StFH gene pairs were evolving through purifying selection, with five gene pairs exhibiting segmental duplications and two pairs exhibiting tandem duplications. Subcellular localization analysis suggested that most of the StFH genes were located in the chloroplast and plasma membrane. Moreover, 54 cis-acting regulatory elements (CAREs) were identified in the promoter regions, some of which were associated with stress responses. According to gene ontology analysis, the majority of the StFH genes were involved in biological processes, with 63 out of 74 GO terms affecting actin polymerization. Six major transcription factor families, including bZIP, C2H2, ERF, GATA, LBD, NAC, and HSF, were identified that were involved in the regulation of StFH genes in various abiotic stresses, including drought. Further, the 60 unique microRNAs targeted 24 StFH by regulating gene expression in response to drought stress were identified. The expression of StFH genes in 14 different tissues, particularly in drought-responsive tissues such as root, stem, shoot apex, and leaf, underscores their significance in managing drought stress. RNA-seq analysis of the drought-resistant Qingshu No. 9 variety revealed the potential role of up-regulated genes, including StFH2, StFH10, StFH19, and StFH25, in alleviating drought stress. Overall, these findings provide crucial insights into the response to drought stress in potatoes and can be utilized in breeding programs to develop potato cultivars with enhanced drought-tolerant traits.

Soybean inoculation with Azospirillum argentinense improves nodulation, grain yield, and alleviates the incidence of Fusarium at field with drought stress

ABSTRACT The efficacy of Azospirillum argentinense REC3, applied by seed inoculation, in enhancing soybean (Glycine max [L.] Merr.) nodulation with native rhizobia, improving grain yield, and protecting against Fusarium fungi was studied. In La Cruz, Tucumán, Argentina, 23 fungal isolates were identified as F. oxysporum (2 strains), F. solani (2), and F. tucumaniae (19). Following soil infestation, only F. tucumaniae was confirmed as a phytopathogen, with REC3 inhibiting its mycelial growth. Greenhouse trials, for a duration of 30 days, showed significant reductions in disease severity (78.2%), root rot (32.3%), and disease incidence (50.9%) in plants susceptible to sudden death syndrome (SDS) when REC3 was applied. Field experiments (2018–2019; January-April) under drought stress conditions, displayed increased nodulation (37.2%) and grain yield (2077 ± 272.8 kg ha−1, p < 0.05) in REC3-treated plants compared to controls (1516 ± 272.8 kg ha−1, p < 0.05). Additionally, a low disease incidence (0.90%) was observed only in the SDS-susceptible soybean variety without REC3 treatment. Overall, the findings showed the significant potential of REC3 inoculation as a biotechnological strategy for enhancing agricultural productivity, managing diseases, and improving crop resilience under challenging environmental conditions. This integrated approach, combining the use of a partially SDS-resistant soybean variety with REC3 inoculation, showed promise in protecting soybean cultivation against SDS and other fungal diseases, thereby ensuring more sustainable and resilient agricultural practices.

Genome-wide identification and analysis of abiotic stress responsiveness of the mitogen-activated protein kinase gene family in Medicago sativa L.

BackgroundThe mitogen-activated protein kinase (MAPK) cascade is crucial cell signal transduction mechanism that plays an important role in plant growth and development, metabolism, and stress responses. The MAPK cascade includes three protein kinases, MAPK, MAPKK, and MAPKKK. The three protein kinases mediate signaling to downstream response molecules by sequential phosphorylation. The MAPK gene family has been identified and analyzed in many plants, however it has not been investigated in alfalfa.ResultsIn this study, Medicago sativa MAPK genes (referred to as MsMAPKs) were identified in the tetraploid alfalfa genome. Eighty MsMAPKs were divided into four groups, with eight in group A, 21 in group B, 21 in group C and 30 in group D. Analysis of the basic structures of the MsMAPKs revealed presence of a conserved TXY motif. Groups A, B and C contained a TEY motif, while group D contained a TDY motif. RNA-seq analysis revealed tissue-specificity of two MsMAPKs and tissue-wide expression of 35 MsMAPKs. Further analysis identified MsMAPK members responsive to drought, salt, and cold stress conditions. Two MsMAPKs (MsMAPK70 and MsMAPK75) responds to salt and cold stresses; two MsMAPKs (MsMAPK60 and MsMAPK73) responds to cold and drought stresses; four MsMAPKs (MsMAPK1, MsMAPK33, MsMAPK64 and MsMAPK71) responds to salt and drought stresses; and two MsMAPKs (MsMAPK5 and MsMAPK7) responded to all three stresses.ConclusionThis study comprehensively identified and analysed the alfalfa MAPK gene family. Candidate genes related to abiotic stresses were screened by analysing the RNA-seq data. The results provide key information for further analysis of alfalfa MAPK gene functions and improvement of stress tolerance.

Enhancing drought resistance in Pinus tabuliformis seedlings through root symbiotic fungi inoculation.

Drought constitutes a major abiotic stress factor adversely affecting plant growth and productivity. Plant-microbe symbiotic associations have evolved regulatory mechanisms to adapt to environmental stress conditions. However, the interactive effects of different fungi on host growth and stress tolerance under drought conditions remain unclear. This study explored the effects of varying polyethylene glycol (PEG-6000) concentrations (0%, 15%, 25%, and 35%) on the growth and physiological responses of two ectomycorrhizal fungi (Suillus granulatus (Sg) and Pisolithus tinctorius (Pt)) and two dark septate endophytes (Pleotrichocladium opacum (Po) and Pseudopyrenochaeta sp. (Ps)) isolated from the root system of Pinus tabuliformis. Specifically, the study aimed to evaluate six inoculation treatments, including no inoculation (CK), single inoculations with Sg, Pt, Po, Ps, and a mixed inoculation (Sg: Pt : Po: Ps = 1:1:1:1), on the growth and physiological characteristics of P. tabuliformis seedlings under different water regimes: well-watered at 70% ± 5%, light drought at 50% ± 5%, and severe drought at 30% ± 5% of the maximum field water holding capacity. All four fungi exhibited the capacity to cope with drought stress by enhancing antioxidant activities and regulating osmotic balance. Upon successful root colonization, they increased plant height, shoot biomass, root biomass, total biomass, and mycorrhizal growth response in P. tabuliformis seedlings. Under drought stress conditions, fungal inoculation improved seedling drought resistance by increasing superoxide dismutase and catalase activities, free proline and soluble protein contents, and promoting nitrogen and phosphorus uptake. Notably, mixed inoculation treatments significantly enhanced antioxidant capacity, osmotic adjustment, and nutrient acquisition abilities, leading to superior growth promotion effects under drought stress compared to single inoculation treatments. All four fungi tolerated PEG-induced drought stress, with increased antioxidant enzyme activities and osmotic adjustment substances and they promoted the growth and enhanced drought resistance of P. tabuliformis seedlings.

Utilizing Infrared Thermometry to Assess the Crop Water Stress Index of Wheat Genotypes in Arid Regions under Varying Irrigation Regimes

Researchers are depending more than ever on remote sensing techniques to monitor and assess the agricultural water status, as well as to estimate crop water usage or crop actual evapotranspiration. In the current work, normal and stressed baselines for irrigated wheat genotypes were developed in an arid part of the Sohag governorate, Egypt, using infrared thermometry in conjunction with weather parameters. The experiment was carried out in a randomized complete block design in the normal and drought stress conditions based on three replicates using ten bread wheat genotypes (G1–G10), including five accessions, under drought stress. A standard Class-A-Pan in the experimental field provided the daily evaporation measurements (mm/day), which was multiplied by a pan factor of 0.8 and 0.4 for normal and stressed conditions, respectively. The relationship between the vapor pressure deficit (VPD) and canopy-air temperature differences (Tc − Ta) was plotted under upper (fully stressed) and lower baseline (normal) equations. Accordingly, the crop water stress indexes (CWSIs) for the stressed and normal baselines for wheat genotypes were developed. Additionally, the intercept (b) and the slope (a) of the lower baseline equation were computed for different genotypes. The results indicate that, before applying irrigation water, the CWSI values were high in both growing seasons and under all irrigation regimes. After that, the CWSI values declined. G10 underwent stress treatment, which produced the greatest CWSI (0.975). Conversely, the G6 condition that received well-watered irrigation yielded the lowest result (−0.007). When compared to a well-watered one, the CWSI values indicated a trend toward rising stress. There existed an inverse link between the CWSI and grain yield (GY); that is, a lower CWSI resulted in better plant water conditions and a higher GY. Under standard conditions, the wheat’s highest GY was recorded in G2, 8.36 Ton/ha and a WCSI of 0.481. In contrast, the CWSI result for the stress treatment was 0.883, indicating a minimum GY of 5.25 Ton/ha. The Water Use Efficiency (WUE) results demonstrated that the stress irrigation regime produced a greater WUE value than the usual one. This study makes a significant contribution by investigating the techniques that would allow CWSI to be used to estimate irrigation requirements, in addition to determining the irrigation time.

The Mitigating Effects of Biostimulant Amendments on the Response of Purslane Plants Grown under Drought Stress Conditions

Portulaca oleracea L. is a wild edible plant with high potential for exploitation in commercial cropping systems due to its nutritional value and great adaptability to abiotic stress conditions. The present study aimed to investigate the response of purslane plants grown under drought stress conditions (100%, 80%, and 60% of field capacity (FC)) and the implementation of biostimulant amendments (control without amendment, plant growth-promoting rhizobacteria (PGPR), mycorrhiza, and effective microorganisms (EMs)) for two consecutive years. In the two-year experiment, the greatest height was recorded in plants grown under no-stress conditions and inoculated with PGPR. The highest branch number, and fresh and dry weight of aboveground and underground parts were observed under no-stress conditions at the mycorrhiza treatment. Moreover, mycorrhiza application in plants growing under 100% FC resulted in the highest N, P, total carbohydrates, and vitamin C and the lowest nitrate and proline contents in leaves. Purslane plants grown under 100% FC and inoculated with PGPR treatment resulted in the highest K and total chlorophyll leaf contents. Additionally, growing plants under mild drought stress (80% FC) combined with biostimulant application (e.g., inoculation with mycorrhiza, PGPR, and EM) may improve plant growth characteristics and mitigate negative stress effects. In general, the applied biostimulant amendments alleviated the adverse effects of drought on plant growth and leaf chemical composition indicating the importance of sustainable strategies to achieve high yield and sufficient quality within the climate change scenario.

Evaluation the impact of silicon nanoparticle on growth and water use efficiency of greenhouse tomato in drought stress condition

This study focused on the effect of silicon nanoparticles (Si-Nps) use on growth and water use efficiency (WUE) of tomato in hydroponic cultivation under drought stress. Experimental treatments included full irrigation, supplying 85 and 70% of crop water requirement (I100, I85 and I70) and use of Si-Nps in three levels of 0, 50 and 100 ppm (N0, N50 and N100) which was performed in a completely randomized design with three replications. Si-Nps were applied in two ways: leaf feeding (L) and root feeding (R). Data analysis showed that different levels of irrigation, Si-Nps and the interaction effect of theirs had a significant effect on fruit weight, leaf fresh and dry weight, stem fresh weight and WUE at 1% level. Si-Nps had a significant effect on stem dry weight at 1% and fruit sugar at 5%. The interaction effect of irrigation and Si-Nps had a significant effect on stem dry weight and fruit sugar at 1%. The maximum fresh fruit weight was related to treatment I85LN100 and compared to the control treatment, it was 7.9% more. The maximum WUE was observed in I70RN50 treatment, which was 56.3% higher than control treatment. Generally, applying irrigation I70RN50 gives the best result for hydroponic tomato cultivation in greenhouse conditions.

Performance of tropical and subtropical maize inbred lines under well-watered and drought-stressed environments

Drought is a major constraint for maize production in sub-Saharan Africa. Developing high-yielding drought-tolerant maize germplasm will safeguard maize yields in the ever-increasing fluctuating rainfall conditions. This study aimed to identify high-yielding inbred lines with stable performance for utilization in hybrid production. One hundred eighty-two (182) maize inbred lines were evaluated under well-watered and drought-stressed conditions at Ukulinga, Makhathini, and Cedara research stations in KwaZulu-Natal, South Africa. The experiments were carried out in a 13 × 14 alpha lattice design with two replications. The inbred lines exhibited significant differences (p ≤ 0.001) for grain yield and yield-related traits under well-watered and drought-stressed environments. The GGE biplot identified three mega-environments, clearly separating drought-stressed from well-watered environments. Inbred lines TZISTR1190, TZISTR1231, TZISTR1261 and CML540 were superior under well-watered conditions, while TZISTR1164 and CML390 performed well under drought condition. TZISTR1190 displayed both high average yield and stability across environments. Inbred lines combining stable high yielding performance in optimum and stress conditions such as TZISTR1190 and TZISTR1231, can be incorporated into local maize breeding pipelines to develop stable high yielding resilient hybrids.

Integrative Analysis of Transcriptomic Profiles and Physiological Responses Provide New Insights into Drought Stress Tolerance in Oil Palm (Elaeis guineensis Jacq.).

Oil palm (Elaeis guineensis Jacq.) is a highly productive crop economically significant for food, cosmetics, and biofuels. Abiotic stresses such as low water availability, salt accumulation, and high temperatures severely impact oil palm growth, physiology, and yield by restricting water flux among soil, plants, and the environment. While drought stress's physiological and biochemical effects on oil palm have been extensively studied, the molecular mechanisms underlying drought stress tolerance remain unclear. Under water deficit conditions, this study investigates two commercial E. guineensis cultivars, IRHO 7001 and IRHO 2501. Water deficit adversely affected the physiology of both cultivars, with IRHO 2501 being more severely impacted. After several days of water deficit, there was a 40% reduction in photosynthetic rate (A) for IRHO 7001 and a 58% decrease in IRHO 2501. Further into the drought conditions, there was a 75% reduction in A for IRHO 7001 and a 91% drop in IRHO 2501. Both cultivars reacted to the drought stress conditions by closing stomata and reducing the transpiration rate. Despite these differences, no significant variations were observed between the cultivars in stomatal conductance, transpiration, or instantaneous leaf-level water use efficiency. This indicates that IRHO 7001 is more tolerant to drought stress than IRHO 2501. A differential gene expression and network analysis was conducted to elucidate the differential responses of the cultivars. The DESeq2 algorithm identified 502 differentially expressed genes (DEGs). The gene coexpression network for IRHO 7001 comprised 274 DEGs and 46 predicted HUB genes, whereas IRHO 2501's network included 249 DEGs and 3 HUB genes. RT-qPCR validation of 15 DEGs confirmed the RNA-Seq data. The transcriptomic profiles and gene coexpression network analysis revealed a set of DEGs and HUB genes associated with regulatory and transcriptional functions. Notably, the zinc finger protein ZAT11 and linoleate 13S-lipoxygenase 2-1 (LOX2.1) were overexpressed in IRHO 2501 but under-expressed in IRHO 7001. Additionally, phytohormone crosstalk was identified as a central component in the response and adaptation of oil palm to drought stress.

Multivariate Analysis Techniques and Tolerance Indices for Detecting Bread Wheat Genotypes of Drought Tolerance

Drought stress is one of the biggest hardships in wheat cultivation because of the strong negative relationship between water deficit and crop yields owing to a lower grain weight, a shorter grain-filling period, a slower grain-filling rate, and reduced grain quality. Genotype–environment interaction (GEN:ENV) generates hardships in selecting wheat genotypes and ideotypes due to biased genetic estimates. Diverse strategies have been proposed to respond to the urgent need for concurrent improvements in yield performance and stability. This study’s purpose was to appraise genetic variation and GEN:ENV effects on yield and yield components to discover drought-stress-tolerant genotypes and ideotypes. This study evaluated 20 genotypes in three consecutive seasons under non-stressful and drought-stress conditions in a total of six ENVs. The broad-sense heritability ranged from 0.54 to 0.82 based on expected mean squares and ranged from 0.60 to 0.90 based on plot mean, but in the other three ways, it was usually greater than 0.90. The high values of (σgen:env2) revealed the effect that broad-sense heritability has on the expression of traits. G01, G03, G06, G07, G08, G10, G12, G13, G16, G17, and G18 were stable genotypes for grain yield (GY), according to additive main effects and a multiplicative interaction biplot for the six ENVs. Based on scores in the weighted average of absolute scores biplot (WAASB), G02, G04, G05, G08, G10, and G18 were selected as stable and high-performance for GY, and they were all selected as the best genotype groups using the WAASB-GY superiority index. From the results obtained from principal component analysis and hierarchical clustering and from the tolerance discrimination indices, G02, G04, G05, G18, and G19 are genotypes that produce a suitable yield under non-stressful and drought-stress conditions. In essence, combining approaches that take into consideration stability and high performance can contribute significantly to enhancing the reliability of recommendations for novel wheat genotypes.

TaMYB-CC5 gene specifically expressed in root improve tolerance of phosphorus deficiency and drought stress in wheat

Phosphate deficiency and drought are significant environmental constraints that impact both the productivity and quality of wheat. The interaction between phosphorus and water facilitates their mutual absorption processes in plants. Under conditions of both phosphorus deficiency and drought stress, we observed a significant upregulation in the expression of wheat MYB-CC transcription factors through the transcriptome analysis. 52 TaMYB-CC genes in wheat were identified and analyzed their evolutionary relationships, structures, and expression patterns. The TaMYB-CC5 gene exhibited specific expression in roots and demonstrated significant upregulation under phosphorus deficiency and drought stress compared to other TaMYB-CC genes. The overexpression of TaMYB-CC5A in Arabidopsis resulted in a significant increase of root length under stress conditions, thereby enhancing tolerance to phosphate starvation and drought stress. The wheat lines with silenced TaMYB-CC5 genes exhibited reduced root length under stress conditions and increased sensitivity to phosphate deficiency and drought stress. In addition, silencing the TaMYB-CC5 genes resulted in altered phosphorus content in leaves but did not lead to a reduction in phosphorus content in roots. Enrichment analysis the co-expression genes of TaMYB-CC5 transcription factors, we found the zinc-induced facilitator-like (ZIFL) genes were prominent associated with TaMYB-CC5 gene. The TaZIFL1, TaZIFL2, and TaZIFL5 genes were verified specifically expressed in roots and regulated by TaMYB-CC5 transcript factor. Our study reveals the pivotal role of the TaMYB-CC5 gene in regulating TaZIFL genes, which is crucial for maintaining normal root growth under phosphorus deficiency and drought stress, thereby enhanced resistance to these abiotic stresses in wheat.

Physiological and biochemical changes of Picea abies (L.) during acute drought stress and their correlation with susceptibility to Ips typographus (L.) and I. duplicatus (Sahlberg)

IntroductionIn recent years, Norway spruce (Picea abies L.) forests in Central Europe have faced escalating threats from bark beetles, primarily Ips typographus (L.), and other species, such as I. duplicatus (Sahlberg). Outbreaks are partially attributed to weakened tree defense resulting from drought periods induced by climate change. This study examines Norway spruce’s physiological and metabolic reactions to acute drought stress during the growing season and evaluates its susceptibility to I. typographus and I. duplicatus.MethodologyIn order to induce drought stress, mature Norway spruces had their roots covered with a roof in April 2021, depriving them of water. Control trees were left with free access to natural rainwater. Over 5 months of the growing season, soil water potential, bark temperature, tree trunk circumference, and sap flow were monitored. Roofed trees and controls were sampled in July, August, and September and analyzed for non-structural carbohydrates and the two classes of defensive compounds, phenolics and terpenes. Furthermore, two different bioassays in tubes and boxes were performed using adult I. typographus and I. duplicatus beetles to assess host choice and acceptance.ResultsRoofed trees exhibited signs of stress as early as July, resulting in decreased tree trunk and a consequent increase in non-structural carbohydrate content. Defensive metabolites remained largely unaffected except for an increase in diterpenes in September. In bioassays, I. typographus preferred boring into the bark of roofed trees in August in tubes and in September in boxes. This increased tree acceptance correlated with increased levels of soluble carbohydrates in the phloem. I. typographus and I. duplicatus beetles showed higher mobility in boxes in August and September on roofed trees but not in July, even though bark surface temperatures were elevated in roof-covered trees during all three bioassay periods.ConclusionThe study revealed rapid physiological responses of trees to acute drought stress, although not many changes were observed in defense traits. Despite the absence of natural bark beetle attacks, drought trees were more accepted by I. typographus than naturally watered trees. This response may indicate the beetles’ preference for trees with phloem of higher nutritional quality induced by the acute drought stress conditions.

Modulatory effects of selenium nanoparticles against drought stress in some grapevine rootstock/scion combinations

BackgroundDrought is a significant abiotic stress that adversely affects plant growth, development, and metabolic processes, thereby reducing plant yield, quality, and production, and threatening global food security. In recent years, nanotechnology has emerged as a promising strategy to overcome the existing environmental challenges and has been tested on some plant species. But it is still awaiting investigation for grapevines. The aim of this study was to investigate the potential of selenium nanoparticles (Se-NPs) to modulate some morphological, physiological, and biochemical parameters in grapevine saplings (5 BB/Crimson Seedless, 41 B/Crimson Seedless, and 1103 P/Crimson Seedless) under drought stress conditions.ResultsIn the study, Se-NP solutions at different concentrations (0 (control), 1, 10, and 100 ppm) were applied by the spray method to wet the entire green surface of grapevine saplings grown under well-irrigated (90–100% field capacity) and drought stress (40–50% field capacity) conditions. Our results showed that 10 ppm Se-NP concentration had the most positive effect, 1 ppm concentration showed limited effects, and 100 ppm concentration led to toxic effects, especially when combined with drought conditions. Se-NP applications at 10 ppm concentration improved the growth parameters (leaf number, leaf area, root fresh and dry weight, shoot fresh and dry weight, etc.) and increased the SPAD index of grapevine saplings under both normal and drought conditions. Additionally, 10 ppm Se-NP applications improved the relative water content (RWC) and stomatal conductance values, proportional to the increases in protein content. On the other hand, under drought conditions, the drought index, leaf temperature, membrane damage index, hydrogen peroxide (H2O2) content, and malondialdehyde (MDA) levels significantly decreased as a result of 10 ppm Se-NP applications, showing an opposite trend. Furthermore, the levels of proline, total phenolics, and antioxidant enzymes (CAT, SOD, and APX) that rose significantly due to drought stress were reduced by 10 ppm Se-NP applications, which also helped to lessen the oxidative stress caused by the drought.ConclusionThe study concluded that foliar application of Se-NPs at 10 ppm significantly enhances drought tolerance in grapevine saplings by improving antioxidant defense, proline and protein accumulation, and overall growth, while lower concentrations are less effective and higher concentrations can cause phytotoxicity. These findings indicate that Se-NPs applications may hold promise not only for grapevines but also for mitigating drought stress effects and improving productivity in other economically important fruit species, warranting further exploration across diverse crop systems.Graphical

Effect of drought acclimation on sugar metabolism in millet.

Drought stress triggers sugar accumulation in plants, providing energy and aiding in protection against oxidative damage. Plant hardening under mild stress conditions has been shown to enhance plant resistance to severe stress conditions. While sugar accumulation and metabolism under drought stress have been well-documented in crop plants, the effect of drought acclimation treatment on sugar accumulation and metabolism has not yet been explored. In this study, we investigated the impact of drought stress acclimation on sugar accumulation and metabolism in the leaves and root tissues of two commonly cultivated foxtail millet (Setaria italica L.) genotypes, 'PI 689680' and 'PI 662292'. Quantification of total sugars (soluble sugar, fructose, glucose, and sucrose), their related enzymes (SPS, SuSy, NI, and AI), and the regulation of their related transcripts (SiSPS1, SiSuSy1, SiSWEET6, SiA-INV, and SiC-INV) revealed that drought-acclimated (DA) plants exhibited levels of these indicators comparable to those of control plants. However, under subsequent drought stress conditions, both the leaves and roots of non-acclimated plants accumulated higher levels of total sugars, displayed increased activity of sugar metabolism enzymes, and showed elevated expression of sugar metabolism-related transcripts compared to drought-acclimated plants. Thus, acclimation-induced restriction of sugar accumulation, transport, and metabolism could be one of the metabolic processes contributing to enhanced drought tolerance in millet. This study advocates for the use of acclimation as an effective strategy to mitigate the negative impacts of drought-induced metabolic disturbances in millet, thereby enhancing global food security and promoting sustainable agricultural systems.

Research Progress on Physiological, Biochemical, and Molecular Mechanisms of Potato in Response to Drought and High Temperature

With the intensifying global warming trend, extreme heat and drought are becoming more frequent, seriously impacting potato yield and quality. To maintain sustainable potato production, it is necessary to breed new potato varieties that are adaptable to environmental changes and tolerant to adversity. Despite its importance, there is a significant gap in research focused on the potential mechanisms of potato resistance to abiotic stresses like drought and high temperatures. This article provides a comprehensive review of the recent research available in academic databases according to subject keywords about potato drought tolerance and high temperature tolerance with a view to providing an important theoretical basis for the study of potato stress mechanism and the selection and breeding of potato varieties with drought and high-temperature resistance. The suitable relative soil moisture content for potato growth and development is 55% to 85%, and the suitable temperature is 15 °C to 25 °C. The growth and development of potato plants under drought and high-temperature stress conditions are inhibited, and plant morphology is altered, which affects the process of potato stolon formation, tuberization and expansion, ultimately leading to a significant reduction in potato tuber yields and a remarkable degradation of the market grade of tubers, the specific gravity of tubers, and the processing quality of tubers. In addition, stress also adversely affects potato physiological and biochemical characteristics, such as reduction in root diameter and leaf area, decrease in net photosynthetic rate of leaves, production of reactive oxygen species (ROS), and increase in membrane lipid peroxidation. In addition, various types of genes and transcription factors are involved in the response to drought and heat at the molecular level in potato. This paper illustrates the effects of stress on potato growth and development and the molecular mechanisms of potato response to adversity in detail, which is intended to reduce the damage caused by drought and high temperature to potato in the context of global warming and frequent occurrence of extreme weather to ensure potato yield and quality and to further safeguard food security.

The flower does not open in the city: evolution of plant reproductive traits of Portulaca oleracea in urban populations.

The impact of urbanization on plant evolution, particularly the evolution of reproductive traits, remains largely unknown. In this study, we aimed to investigate the consequences of urbanization on the reproductive traits of Portulaca oleracea in the Kantō region of Japan. Portulaca oleracea has a unique cleistogamous reproductive system, which consists of genetically determined chasmogamous (open, CH) and cleistogamous (closed, CL) plants. We collected seeds of P. oleracea from ten populations in rural areas and ten populations in urban areas. In a common garden experiment, we recorded the type of flowers (CH or CL), reproductive phenology and seed production. All individuals produced either CH or CL flowers, allowing us to classify them as either CH or CL plants. We observed a significant difference in the prevalence of CH and CL plants between rural and urban populations: the number of CH plants was generally low and was particularly low among urban individuals. Compared to CH plants, CL plants showed earlier phenology and produced heavier seeds, which is consistent with stress avoidance in response to heat and drought stress conditions in urban areas. Our findings suggest that urbanization may drive an evolutionary change in the cleistogamous reproductive system of P. oleracea. CL plants with earlier phenology and larger seeds might be better adapted to urban environments, where they are subjected to harsh heat and drought stress.

Unravelling the impact of drought and salt stresses on Thymus pannonicus: Morpho-physiological and biochemical insights

This research assesses the effects of drought and salt stresses applied individually or in combination on Thymus pannonicus, a resilient perennial herb native to the Pannonian vegetation region. Our experiment aimed to comprehensively evaluate morphological, physiological, and biochemical parameters of the thyme subjected to two levels of soil water capacity (SWC) - 70 % (control and salt stress) and 40 % (drought stress and combined stresses) - along with two salinity levels, 0 mM NaCl (control and drought stress) and 60 mM NaCl (salt stress and combined stresses). The plants exhibited significant responses to all the studied parameters under 40 % SWC in both treatments, demonstrating notable reductions in shoot and root parameters. In contrast, salt treatment at 60 mM had a minimal impact on growth. A stability in photosynthetic pigment composition was observed in all treatment, whereas a notable decrease (p < 0.05) in relative water content was seen in drought-stressed treatments compared to the to the control. Essential oil contents were higher in the control (0.91 ml/100g DW) but significantly declined (p < 0.05) under drought stress and combined stresses conditions (0.49 ml/100g DW and 0.53 ml/100g DW respectively). Particularly, the GC-MS analysis revealed a significant decrease (p < 0.05) in thymol and carvacrol content for the drought-stressed treatments. Substantial reductions were evident for the total polyphenol concentration and antioxidant capacity under the combined stress treatment, measuring 101.49 mg GAE/g DW and 106.57 AAE/g DW, respectively. Interestingly, the HPLC analysis indicated the highest levels of rosmarinic acid and caffeic acid in the drought-stressed treatment, while the lowest ones were recorded in the combined stress treatment. These findings indicated the responses of Thymus pannonicus to environmental stressors, emphasizing the need for further investigations for a comprehensive understanding of salinity effects.

Impact of high temperature and drought stress on the microbial community in wolf spiders

High temperatures and drought present significant abiotic challenges that can limit the survival of many arthropods, including wolf spiders, which are ectothermic and play a crucial role in controlling pest populations. However, the impact of these stress factors on the microbiota of spiders remains poorly understood. In this study, we utilized 16 S rRNA gene sequencing to explore the diversity and composition of bacterial communities within Pardosa pseudoannulata under conditions of high temperature and drought stress. We found that Firmicutes, Bacteroidetes, and Proteobacteria were the predominant bacterial phyla present. Analyses of alpha diversity indicated an increase in bacterial diversity under combined stress conditions, as reflected by various diversity indices such as Ace, Chao1, Shannon, and Simpson. Furthermore, co-occurrence network analysis highlighted intricate interactions among the microbial taxa (e.g., Enterobacter, Chitinophaga, and Eubacterium), revealing the adaptive complexity of the spider's microbiome to environmental stress. Functional prediction analysis suggested that combined stress conditions might enhance key metabolic pathways, particularly those related to oxidative phosphorylation and amino acid metabolism. Using Random Forest analysis, we determined that changes in three heat shock proteins were largely attributed to variations in bacterial communities, with Firmicutes being notably influential. Collectively, this in-depth analysis offers novel insights into the responses of microbial communities within spider microbiomes to combined abiotic stresses, providing valuable information for understanding extreme climate impacts and informing ecological management strategies.

Chitosan and its Nanoform Regulates Physiological Processes and Antioxidant Mechanisms to Improve Drought Stress Tolerance of Vicia faba Plant

Purpose: Drought stress is an important challenge to global food security and agricultural output. Dramatic and quick climate change has made the problem worse. It caused unexpected impacts on the growth, development, and yield of different plants. Hence, the ultimate yield does not fulfill the required demand. Understanding the biochemical, ecological, and physiological reactions to these pressures is essential for improved management. Chitosan applications have a wide prospect of addressing abiotic issues. Moreover, chitosan and chitosan nanoparticles have a positive impact on increasing plant tolerance to abiotic stress, like drought stress. The current research investigated the consequences of drought stress on the morpho-physiological and biochemical parameters of Vicia faba plants, a comparison of chitosan and chitosan nanoparticles, and their ameliorating capacity towards drought stress. Methods: A pot experiment was conducted to evaluate the beneficial role of either chitosan (0.5, 1.0, and 2.0 gL− 1) or chitosan NPs (10, 20, and 30 mgL− 1) in inducing the Vicia faba tolerance to drought stress (60% water field capacity). Results: Drought stress significantly affected vegetative growth parameters of the shoot system, photosynthetic pigments, and indole acetic acid, accompanied by significant increases in vegetative growth parameters of the root system, some chemical composition of dry leaf tissues (total soluble sugar, soluble protein, proline, phenolic compound, glutathione, α tocopherol), hydrogen peroxide, malonialdehyde, lipoxygenase, and antioxidant enzyme activities (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, glutathione reductase). All applied treatments. chitosan and chitosan nanoparticles, at all concentrations, improved plant tolerance to drought stress via increasing vegetative growth parameters, photosynthetic pigments, indole acetic acid, total soluble sugar, soluble protein, proline, phenolic compound, glutathione, α tocopherol, and antioxidant enzyme activities, accompanied by decreases in hydrogen peroxide, malondialdehyde, and lipoxygenase enzyme. It is worthy to mention that 20 mgL− 1 chitosan nanoparticles was the most optimal treatment either under well water conditions (90% water field capacity) or drought stress conditions (60% water field capacity). Moreover, it is obvious from these results that the response of bean plants grown under well watered conditions was more pronounced than that of those plants grown under drought stress conditions to 20 mgL− 1 chitosan nanoparticles. Conclusions: Hence, it can be concluded that chitosan and chitosan nanoparticles can mitigate the negative impacts of drought stress by improving the photosybthetic pigments, endogenous indole acetic acid, and osmolyte contents, as well as the non-enzymatic and enzymatic antioxidant compounds of the Vicia faba plant.

Stress Management Practices in Rainfed Sorghum (K12) on Yield, Economics and Plant Nutrient Uptake Through Foliar Plant Nutrition Under Typical Vertisols (Typic chromusterts) of Semiarid Region

ABSTRACT Foliar fertilization has great potential to give higher yields under intensive cropping system and in enhancing the crop tolerance to drought conditions. Different responses of yield to foliar fertilization are probably associated with incorrect timing of application, use of inappropriate fertilizer and lack of concern of soil available nutrients and environmental conditions. Though soil application of nutrients cannot be replaced totally with foliar fertilization, but under various situations like rainfed condition, foliar nutrition can play very important role in enhancing crop yield and nutrient use efficiency. Focusing on this, a field experiment was conducted in the Agricultural Research Station, Kovilpatti, under rainfed situation from 2017 to ‘20 to evaluate the response of foliar application of plant nutrients sprayed during moisture stress condition and to improve the growth and yield of sorghum under rainfed condition. This experiment was laid out in split plot design with replicated thrice and the treatments consisted of main plots: M1 – foliar spray during dry spell, M2 – foliar spray after relieving of stress/dry spell (with favorable soil moisture) and subplots: S1 – urea@1%, S2 – urea@2%, S3 – water soluble complex fertilizer (19:19:19)@0.5%, S4 – water soluble complex fertilizer (19:19:19)@0.5% + recommended dose of micronutrient for foliar spray (to be decided based on soil test: zinc, boron, iron, manganese, etc.), S5 – ZnSO4@0.5%, S6 – water spray, S7 – control (no spray of any material/water) under rainfed vertisols of semiarid region. The obtained results showed that the application of water soluble complex fertilizer (19:19:19)@0.5% sprayed during the dry spell significantly increased the plant height, earhead length and grain test weight. This attributes resulted in higher grain yield (1448 kg ha−1), stover yield (2288 kg ha−1), net returns (Rs. 8748 ha−1), B:C (1.16) and rainwater use efficiency (3.85 kg ha−1-mm) when compared to other practices in rainfed sorghum. There is a gradual increase in total major plant nutrient uptake, viz. nitrogen (22.3 kg ha−1), phosphorus (4.56 kg ha−1) and potassium uptake (26.0 kg ha−1) with the foliar application of water soluble complex fertilizer (19:19:19)@0.5% applied during the dry spell condition (S3) during drought stress condition (M1). Foliar application of nutrients along with soil application has several advantages in supplementing the nutritional requirements of crops such as rapid and efficient response by the plants, less product needed and independence of soil conditions. Foliar nutrition designed to eliminate the problems like fixation and immobilization of nutrients. Hence, foliar nutrition is recognized as an important method of fertilization during the dry spell under rainfed condition in modern agriculture.