Drought Stress Resistance Research Articles

Exogenous SNP Alleviates Drought Stress in Wheat During the Grain-Filling Stage by Modulating TaP5CS Gene Transcription.

Drought stress severely damages wheat growth and photosynthesis, and plants at the grain-filling stage are the most sensitive to drought throughout the entire period of development. Exogenous spraying of sodium nitroprusside (SNP) can alleviate the damage to wheat caused by drought stress, but the mechanism regulating the proline pathway remains unknown. Two wheat cultivars, drought-sensitive Zhoumai 18 and drought-tolerant Zhengmai 1860, were used as materials when the plants were cultivated to the grain-filling stage. The results show that under drought stress, SNP pretreatment effectively improved the physiological basis of photosynthesis and water use efficiency of the two cultivars, increased their tolerance to photosystem II (PSII) damage, and maintained a normal photosynthetic rate and yield. Drought stress induced an increase in pyrroline-5-carboxylate synthase (TaP5CS) gene transcription, and a comparatively greater increase was detected in Zhengmai 1860. When SNP treatment was applied before drought exposure, TaP5CS transcription was further enhanced. Induction of TaP5CS transcription promoted proline accumulation in response to drought stress, increased osmotic ability, and maintained the net photosynthetic rate, thereby increasing the accumulation of dry matter and yield traits. In this study, exogenous SNP regulates the transcription of genes related to the proline metabolism pathway and provides a theoretical basis for the establishment of wheat cultivation technology using SNP to resist drought stress.

Identification and functional analyses of drought stress resistance genes by transcriptomics of the Mongolian grassland plant Chloris virgata

BackgroundMongolian grasslands, including the Gobi Desert, have been exposed to drought conditions with few rains. In such harsh environments, plants with highly resistant abilities against drought stress survive over long periods. We hypothesized that these plants could harbor novel and valuable genes for enhancing drought stress resistance.ResultsIn this study, we identified Chloris virgata, a Mongolian grassland plant with strong drought resistance. RNA-seq-based transcriptome analysis was performed to uncover genes associated with drought stress resistance in C. virgata. De novo transcriptome assembly revealed 25,469 protein-coding transcripts and 1,219 upregulated genes after 3- and 6-hr drought stress treatments. Analysis by homology search and Gene Ontology (GO) enrichment indicated that abscisic acid (ABA)- and drought stress-related GO terms were enriched. Among the highly induced genes, ten candidate cDNAs were selected and overexpressed in Arabidopsis. When subjected to drought stress, three of these genes conferred strong drought resistance in the transgenic plants. We named these genes Mongolian Grassland plant Drought-stress resistance genes 1, 2, and 3 (MGD1, MGD2, and MGD3). Gene expression analyses in the transformants suggested that MGD1, MGD2, and MGD3 may activate drought stress-related signalling pathways.ConclusionThis study highlighted the drought resistance of C. virgata and identified three novel genes that enhance drought stress resistance.

Studies on the Physiological Response of Hemerocallis middendorffii to Two Types of Drought Stresses.

Drought is a major environmental factor limiting plant growth and development. Hemerocallis middendorffii is a perennial herbaceous plant with high drought resistance, and high ornamental and application values. Understanding the mechanism of drought stress resistance in H. middendorffii is helpful for better utilization of plant resources and selection of excellent germplasms. In this study, the phenological and physiological traits of H. middendorffii were comprehensively analyzed under natural drought stress (ND) and PEG-simulated drought stress (PD), and the resistance of H. middendorffii to different levels of drought stress was evaluated. ND was treated using a natural water loss method. PD was treated under drought stress by using PEG-6000. H. middendorffii were able to grow within 15 d of ND and 4 d of 20% PD. Beyond this drought time, H. middendorffii will wilt and lose their ornamental value. Further study showed that H. middendorffii protect themselves from damage and enhance drought resistance mainly by increasing the content of osmoregulatory substances, enhancing the activity of antioxidant enzymes, and inhibiting photosynthesis. Malondialdehyde (MDA) content accumulated rapidly at 15 d of ND and 7 d of PD. Antioxidant enzyme activities peaked at 15 d of ND and 4 d of PD. Photosynthetic parameters decreased at 15 d of ND and 4 d of 20% PD, respectively. Moreover, we identified that the HmWRKY9 gene was up-regulated for expression in the leaves after ND and PD. HmWRKY9 may be involved in regulating the response of H. middendorffii to drought stress.

Effect of saline concentrations and humidity percentage on alfalfa va-rieties (Medicago sativa L.) from the Mexicali Valley, Mexico.

Objective: The aim of this experiment was to identify alfalfa varieties resistant to salt and drought stress in Mexicali Valley Mexico. Design/methodology/approach: Four alfalfa (M. sativa L.) varieties were used: Cuf-101 C, FD9, Pioneer and Cuf-101 P. Drought stress resistance was evaluated using four different percentages of commercial peat moss substrate (100%, 50%, 25%, and 15%), and saline stress resistance was evaluated by applying four concentrations of NaCl (0 mM, 50 mM, 100 mM, and 200 Mm.The variables evaluated in each treatment were: plant height, number of leaves and root length. The data obtained were subjected to an analysis of variance using the SAS statistical package version 9.0 with an α=0.5. Results: Alfalfa variety Cuf-101 had a good adaptation to both stresses with an average height of 11.28 cm and an average number of leaves of 3.54. Seed germination of alfalfa varieties (M. sativa L.) subjected to salt stress were affected even at the lowest NaCl concentration. Conclusions: The alfalfa variety with the highest germination percentage in all NaCl concentrations was Cuf-101 C with 91.17%.

Transcription factor ZjABF1 promotes sugar accumulation and abiotic resistance by positively regulating the expression of sugar transport protein ZjSWEET11 and ZjSWEET18 in Chinese jujube.

Chinese jujube (Ziziphus jujuba Mill.) exhibits a remarkable resilience to both drought and salinity. Additionally, it is characterized by a high sugar content, with sucrose being the predominant component of its soluble sugars. However, the molecular mechanisms linking robust abiotic stress resistance, sugar accumulation and sugar transport proteins ZjSWEETs remain poorly understood in jujube. In this study, we identified two critical sugar transport proteins, ZjSWEET11 and ZjSWEET18, in Chinese jujube through comprehensive assays and established a positive correlation between sucrose accumulation and the expression of these genes. Furthermore, we discovered that the key transcription factor ZjABF1 within the ABA signaling pathway positively regulated the transcriptional expression of ZjSWEET11 and ZjSWEET18 and increased the sugar contents, consequently improving the drought and salt stress resistance of plants. Basing on these results, we proposed a working module that ZjABF1 promotes sugar accumulation and improves stress resistance by targeting and up-regulating of ZjSWEET11 and ZjSWEET18. Our findings provide valuable insights into the mechanisms underlying sugar accumulation and abiotic stress adaptation in Chinese jujube.

Genome-Wide Identification and Expression Analysis of the Alfalfa (Medicago sativa L.) U-Box Gene Family in Response to Abiotic Stresses.

E3 ubiquitin ligases known as plant U-box (PUB) proteins regulate a variety of aspects of plant growth, development, and stress response. However, the functions and characteristics of the PUB gene family in alfalfa remain unclear. This work involved a genome-wide examination of the alfalfa U-box E3 ubiquitin ligase gene. In total, 210 members were identified and divided into five categories according to their homology with the members of the U-box gene family in Arabidopsis thaliana. The phylogenetic analysis, conserved motifs, chromosomal localization, promoters, and regulatory networks of this gene were investigated. Chromosomal localization and covariance analyses indicated that the MsPUB genes expanded MsPUB gene family members through gene duplication events during evolution. MsPUB genes may be involved in the light response, phytohormone response, growth, and development of several biological activities, according to cis-acting element analysis of promoters. In addition, transcriptome analysis and expression analysis by qRT-PCR indicated that most MsPUB genes were significantly upregulated under cold stress, drought stress, and salt stress treatments. Among them, MsPUBS106 and MsPUBS185 were significantly and positively correlated with cold resistance in alfalfa. MsPUBS110, MsPUBS067, MsPUBS111 and MsPUB155 were comprehensively involved in drought stress, low temperature, and salt stress resistance. All things considered, these discoveries offer fresh perspectives on the composition, development, and roles of the PUB gene family in alfalfa. They also provide theoretical guidance for further investigations into the mechanisms regulating the development, evolution, and stress tolerance of MsPUB.

Comparative transcriptome analysis of B. oleracea L. var. italica and B. macrocarpa Guss. genotypes under drought stress: de novo vs reference genome assembly

Drought stress influences plant growth and development affecting some physiological processes during the growing cycle. The improvement of the drought stress resistance of the plant will allow the reduction of the water requirements of the crops, representing the new frontier for agriculture, as consequence of the ongoing climatic changes. The individuation of genetic features useful for enhancing the reduction of water use and the plant drought resistance will be one of the key strategy for providing enough food for the foreseen increment of the global population. Nowadays, the cultivars used for modern agriculture show a narrow genetic diversity due to the domestication process carried out of each crop, resulting with a less adaptation to the environmental conditions affected by both antropic activities and the climatic change in act. Among the several grown species, Brassica oleracea L. (n = 9) crops are particularly vulnerable to the adverse effects of water deficiency. Transcriptomic analysis is a powerful tool that allows researchers to identify genes and pathways, that are activated or repressed in response to each specific stress, elucidating the complex regulatory networks that underlie the correspondent response. To individuate the differentially expressed genes we compared two drought-sensitive B. oleracea L. var. botritis x italica Sicilian landraces and two drought-tolerant B. macrocarpa Guss populations grown in ordinary irrigation regimes and in water deficit conditions. Their transcriptome was obtained by a RNAseq approach. The individuated sensible and tolerant drought stress genotypes showed significant difference for H2O2 content, leaf area and SPAD index (Soil Plant Analysis Development). For better identify crucial genes and pathways associated with drought stress response of both the sensible and tolerant genotypes a thorough evaluation of both de novo assembly and reference B. oleracea var. italica genome-based assembly was conducted. The comparison of the transcriptomes allowed to identify the crucial genes and pathways associated with tolerance to drought stress in Brassica oleracea L. crops. As main results, we individuated one gene coding transcription factor showing opposite behavior in the sensitive and tolerant signatures. The adoption of two transcriptome assembly methods provided a more comprehensive dataset, enabling an unbiased interpretation of the outcomes.

The role of salicylic acid in modulating phenotyping in spring wheat varieties for mitigating drought stress

Climate change-related droughts that recur frequently are one of the biggest obstacles to wheat (Triticum aestivum L.) productivity. Worldwide, attempts are being done to establish drought-resistant cultivars. However, progress is slow since drought tolerance is a complex trait controlled by numerous genes, and its expression is influenced by the environment. Phenotypic, biochemical physiological, and genotyping approaches are highlighted as critical research components for leveraging genetic variation in eight wheat genotypes. Treatments included eight spring wheat genotypes (IPK_040, IPK_046, IPK_050, IPK_071, IPK_105, WAS_007, WAS_024 and WAS_031), normal irrigation (NI), drought stress (D) (30% field capacity (FC)), normal irrigation with 0.5 mM SA (NSA), and drought treated with SA (DSA). The results revealed that there was a reduction in relative water content, an increase membrane leakage, and leaf chlorophyll content under drought stress. SA induced the defense responses against drought by increasing the osmolytes and the antioxidative enzymes activities. Compared to the NI group, the DSA treatment improved the water regulation, antioxidant capacity, and drought stress resistance. SA significantly reduced the deleterious effects of water stress on phenotyping more in WAS_ 024 and IPK_ 105 genotypes. The most responsive genotypes to salicylic acid were IPK_ 046 among the IPK genotypes, whereas WAS_031 genotype was amongst WAS genotypes based on the morpho-physiological traits. The findings of this study give a solid foundation for assessing drought resistance in T. aestivum and developing cultivation-specific water management methods.Graphical

Physiological and metabolomic analyses reveal the mechanism by which exogenous spermine improves drought resistance in alfalfa leaves (Medicago sativa L.).

Alfalfa (Medicago sativa L.) is a globally important legume crop with high nutritional and ecological value. Drought poses a serious threat to alfalfa acreage and yields. Spermine (Spm) has been shown to protect plants from drought damage. The aim of this study was to clarify the mechanism of exogenous Spm to improve drought resistance of alfalfa. In this study, we root applied 0.1, 0.5, and 1 mM Spm to Gannong No. 3 (G3) alfalfa under drought stress, and then determined their physiological and metabolic changes. The results showed that exogenous Spm increased chlorophyll content, chlorophyll fluorescence parameters and gas exchange parameters, enhanced antioxidant enzymes activity, improved ascorbic acid-glutathione (AsA-GSH) cycle, increased osmoregulatory substances content, reduced hydrogen peroxide and superoxide anion levels, and inhibited malondialdehyde accumulation in alfalfa under drought stress, thereby increasing plant height and leaf relative water content and enhancing drought tolerance of alfalfa. The redundancy analysis of the above physiological indicators showed that the addition of the optimal Spm to improve drought tolerance of alfalfa under drought stress was mainly achieved by increasing catalase activity and improving the ASA-GSH cycle. In addition, metabolomics analysis revealed that exogenous Spm increased the content of oxobutanedioic acid, citric acid, fumaric acid and malic acid to enhance the tricarboxylic acid cycle. Meanwhile, exogenous Spm increased endogenous Spm and proline (Pro) content to resist drought stress by enhancing Spm and Pro metabolism. Moreover, exogenous Spm increased the accumulation of the signaling substance abscisic acid. In conclusion, exogenous Spm enhanced drought resistance of alfalfa leaves under drought stress.

Genome-wide identification and expression analysis of CmoADHs in Cucurbita moschata—Critical role of CmoADH9 in drought tolerance

In plants, alcohol dehydrogenases (ADHs) are involved in stress response, organ development, fruit ripening, and metabolite synthesis. However, little is known regarding ADH-encoding genes (ADHs) in Cucurbita moschata which is usually used as a rootstock for cucumber, melon, watermelon, and other cucurbit crops to resist soil-borne diseases and abiotic stresses. We identified 11 CmoADHs in the C. moschata genome that were unevenly distributed across seven chromosomes. These genes were predicted to encode stable cytoplasmic acidic proteins, sharing a low degree of identity with each other. The genes exhibited different intron–exon structures. Analysis of cis-acting regulatory elements showed that CmoADHs contain environmental stress-, hormone response-, light response-, and development/tissue specificity-related elements in their promoters. Expression pattern analysis revealed that CmoADH2, CmoADH3, CmoADH4, CmoADH9, CmoADH10, and CmoADH11 had the highest expression levels in the roots, which were significantly higher than those in the other tested tissues. These six genes may play important roles in the growth and development of roots, and in related abiotic stress responses. CmoADH1, CmoADH5, CmoADH6, CmoADH7, CmoADH8 had the highest expression in the apical region and could be involved in the differentiation of newly formed tissues. To study the role of CmoADHs in abiotic stress, salt, drought, low temperature, and ethephon treatments were performed. Under drought conditions, CmoADHs showed different expression trends. The expression levels of CmoADH1, CmoADH2, CmoADH3, and CmoADH9 increased significantly and peaked after 1 h of drought treatment, indicating that these four genes are more sensitive to drought stress. Under salt treatment, all CmoADHs showed a significant increase or decrease in expression within 6 h, except for CmoADH5 and CmoADH10, which were insensitive to salt treatment. The expression of most of the CmoADHs was significantly downregulated by low-temperature treatment. Ethephon treatment significantly induced the expression of all the CmoADHs, except CmoADH2, to different degrees within 12 h. CmoADH9 was found to be involved in root growth and drought stress resistance. Identification of these ADH genes can provide useful resources for conferring stress resistance in other economically important crops.

Identification of long-chain acyl-CoA synthetase gene family reveals that SlLACS1 is essential for cuticular wax biosynthesis in tomato

Long-chain acyl-CoA synthetases (LACSs), belonging to the acyl-activating enzyme superfamily, play crucial roles in lipid biosynthesis and fatty acid catabolism. Here, we identified 11 LACS genes in the tomato reference genome, and these genes were clustered into six subfamilies. Gene structure and conserved motif analyses indicated that LACSs from the same subfamily shared conserved gene and protein structures. Expression analysis revealed that SlLACS1 was highly expressed in the outer epidermis of tomato fruits and leaves. Subcellular localization assay results showed that SlLACS1 was located in the endoplasmic reticulum. Compared with wild-type plants, the wax content on leaves and fruits decreased by 22.5–34.2 % in SlLACS1 knockout lines, confirming that SlLACS1 was involved in wax biosynthesis in both leaves and fruits. Water loss, chlorophyll extraction, water-deficit, and toluidine blue assays suggested that cuticle permeability was elevated in SlLACS1 knockout lines, resulting in reduction in both drought stress resistance and fruit shelf-life. Overall, our analysis of the LACSs in tomato, coupled with investigations of SlLACS1 function, yielded a deeper understanding of the evolutionary patterns of LACS members and revealed the involvement of SlLACS1 in wax accumulation contribute to drought resistance and extended fruit shelf-life in tomato.

Effects of Drought Stress on Key Enzymes in Soybean Carbon and Nitrogen Metabolism

Background: The synthesis and catalysis of enzymes are inherently linked to the presence of water and drought-induced water deficit in plants can adversely impact enzyme activity. Drought severely impairs the growth and development of crops, with the extent of its impact varying according to the severity of the water scarcity. Drought also regulates the activity of carbon and nitrogen metabolizing enzymes in plants. Methods: To investigate the effects of varying degrees of drought on soybeans, this study selected HN44 (drought-resistant variety) and HN65 (drought-sensitive variety) as subjects through sand culture and assessed the changes in key enzymes involved in carbon and nitrogen metabolism within the soybean leaves in 2022. Result: The results indicated that short-term drought stress increased the activities of sucrose synthase (SUS), Sucrose Phosphate Synthase (SPS) and Glutamine Synthetase (GS), while decreasing the activity of nitrate reductase (NR). In contrast, prolonged drought reduced the activities of SUS and GS. This study provides a theoretical foundation for enhancing the drought stress resistance of soybeans.

Calcium-Dependent Protein Kinase GhCDPK16 Exerts a Positive Regulatory Role in Enhancing Drought Tolerance in Cotton.

Cotton is essential for the textile industry as a primary source of natural fibers. However, environmental factors like drought present significant challenges to its cultivation, adversely affecting both production levels and fiber quality. Enhancing cotton's drought resilience has the potential to reduce yield losses and support the growth of cotton farming. In this study, the cotton calcium-dependent protein kinase GhCDPK16 was characterized, and the transcription level of GhCDPK16 was significantly upregulated under drought and various stress-related hormone treatments. Physiological analyses revealed that the overexpression of GhCDPK16 improved drought stress resistance in Arabidopsis by enhancing osmotic adjustment capacity and boosting antioxidant enzyme activities. In contrast, silencing GhCDPK16 in cotton resulted in increased dehydration compared with the control. Furthermore, reduced antioxidant enzyme activities and downregulation of ABA-related genes were observed in GhCDPK16-silenced plants. These findings not only enhanced our understanding of the biological functions of GhCDPK16 and the mechanisms underlying drought stress resistance but also underscored the considerable potential of GhCDPK16 in improving drought resilience in cotton.

Comparative Effects of Water Scarcity on the Growth and Development of Two Common Bean (Phaseolus vulgaris L.) Genotypes with Different Geographic Origin (Mesoamerica/Andean).

Drought stress is widely recognized as a highly detrimental abiotic stress factor that significantly impacts crop growth, development, and agricultural productivity. In response to external stimuli, plants activate various mechanisms to enhance their resistance or tolerance to abiotic stress. The common bean, a most important legume according to the FAO, serves as a staple food for millions of people worldwide, due to its rich protein, carbohydrate, and fiber content, concurrently, and water scarcity is the main factor limiting common bean production. The process of domestication and on-farm conservation has facilitated the development of genotypes with varying degrees of drought stress resistance. Consequently, using landraces as biological material in research can lead to the identification of variants with superior resistance qualities to abiotic stress factors, which can be effectively integrated into breeding programs. The central scope of this research was to find out if different geographic origins of common bean genotypes can determine distinct responses at various levels. Hence, several analyses were carried out to investigate responses to water scarcity in three common bean genotypes, M-2087 (from the Mesoamerican gene pool), A-1988 (from the Andean gene pool) and Lechinta, known for its high drought stress resistance. Plants were subjected to different water regimes, followed by optical assessment of the anatomical structure of the hypocotyl and epicotyl in each group; furthermore, the morphological, physiological, and biochemical parameters and molecular data (quantification of the relative expression of the thirteen genes) were assessed. The three experimental variants displayed distinct responses when subjected to 12 days of water stress. In general, the Lechinta genotype demonstrated the highest adaptability and drought resistance. The M-2087 landrace, originating from the Mesoamerican geographic basin, showed a lower resistance to water stress, compared to the A-1988 landrace, from the Andean basin. The achieved results can be used to scale up future research about the drought resistance of plants, analyzing more common bean landraces with distinct geographic origins (Mesoamerican/Andean), which can then be used in breeding programs.

Characterization of bZIP Transcription Factors in Transcriptome of Chrysanthemum mongolicum and Roles of CmbZIP9 in Drought Stress Resistance.

bZIP transcription factors play important roles in regulating plant development and stress responses. Although bZIPs have been identified in many plant species, there is little information on the bZIPs in Chrysanthemum. In this study, bZIP TFs were identified from the leaf transcriptome of C. mongolicum, a plant naturally tolerant to drought. A total of 28 full-length bZIP family members were identified from the leaf transcriptome of C. mongolicum and were divided into five subfamilies based on their phylogenetic relationships with the bZIPs from Arabidopsis. Ten conserved motifs were detected among the bZIP proteins of C. mongolicum. Subcellular localization assays revealed that most of the CmbZIPs were predicted to be localized in the nucleus. A novel bZIP gene, designated as CmbZIP9, was cloned based on a sequence of the data of the C. mongolicum transcriptome and was overexpressed in tobacco. The results indicated that the overexpression of CmbZIP9 reduced the malondialdehyde (MDA) content and increased the peroxidase (POD) and superoxide dismutase (SOD) activities as well as the expression levels of stress-related genes under drought stress, thus enhancing the drought tolerance of transgenic tobacco lines. These results provide a theoretical basis for further exploring the functions of the bZIP family genes and lay a foundation for stress resistance improvement in chrysanthemums in the future.

Identification and Analysis of PPO Gene Family Members in Paulownia fortunei.

Polyphenol oxidase (PPO) is a common metalloproteinase in plants with important roles in plant responses to abiotic and biotic stresses. There is evidence that PPOs contribute to stress responses in Paulownia fortunei. In this study, PPO gene family members in P. fortunei were comprehensively identified and characterized using bioinformatics methods as well as analyses of phylogenetic relationships, gene and protein structure, codon usage bias, and gene expression in response to stress. The genome contained 10 PPO gene family members encoding 406-593 amino acids, with a G/C bias. Most were localized in chloroplasts. The motif structure was conserved among family members, and α-helices and random coils were the dominant elements in the secondary structure. The promoters contained many cis-acting elements, such as auxin, gibberellin, salicylic acid, abscisic acid, and photoresponsive elements. The formation of genes in this family was linked to evolutionary events, such as fragment replication. Real-time quantitative PCR results showed that PfPPO7, PfPPO10, PfPPO1, PfPPO2, PfPPO3, PfPPO4, PfPPO5, and PfPPO8 may be key genes in drought stress resistance. PfPPO1, PfPPO3, PfPPO4, and PfPPO10 were resistant stress-sensitive genes. These results provide a reliable basis for fully understanding the potential functions of these genes and the selection of resistance breeding.

Hydration and dehydration cycles for enhanced soursop (Annona muricata) seedling quality and seedling drought stress resistance

Hydration and dehydration cycles for enhanced soursop (Annona muricata) seedling quality and seedling drought stress resistance

Response of selenium pools to drought stress by regulating physio‑biochemical attributes and anatomical changes in Gentiana macrophylla

Selenium (Se), as a vital stress ameliorant, possesses a beneficial effect on mediating detrimental effects of environmental threats. However, the mechanisms of Se in mitigating the deleterious effects of drought are still poorly understood. Gentiana macrophylla Pall. is a well-known Chinese medicinal herb, and its root, as the main medicinal site, has significant therapeutic effects. The purpose of this experiment was to investigate the functions of Se on the seedling growth and physiobiochemical characteristics in G. macrophylla subjected to drought stress. The changes in microstructure and chloroplast ultrastructure of G. macrophylla leaves under drought exposure were characterized by scanning electron microscopy (SEM), scanning electron microscopes and energy dispersive X-Ray spectroscope (SEM-EDX), and transmission electron microscopy (TEM), respectively. Results revealed that drought stress induced a notable increase in oxidative toxicity in G. macrophylla, as evidenced by elevated levels of hydrogen peroxide (H2O2), lipid peroxidation (MDA), enhanced antioxidative response, decreased plant photosynthetic function, and inhibited plant growth. Chloroplasts integrity with damaged membranes and excess osmiophilic granule were observed in the drought-stressed plants. Se supplementation notably recovered the stomatal morphology, anatomical structure damage, and chloroplast ultrastructure of G. macrophylla leaves caused by drought exposure. Exogenous Se application markedly enhanced SPAD, photosynthetic stomatal exchange parameters, and photosystem II activity. Se supplementation significantly promoted the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT), while reducing levels of MDA, superoxide anion (O2–.) and H2O2, and improving membrane integrity. Furthermore, the ameliorative effects of Se were also suggested by increased contents of osmotic substances (soluble sugar and proline), boosted content of gentiopicroside and loganinic acid in roots, and alleviated the inhibition in plant growth and biomass. Fourier transform infrared (FTIR) analysis of Se-treated G. macrophylla roots under drought stress demonstrated that Se-stimulated metabolites including O-H, C-H, N-H, C-N, and CO functional groups, were involved in resisting drought stress. Correlation analysis indicated an obvious negative correlation between growth parameters and MDA, O2–. and H2O2 content, while a positive correlation with photosynthetic gas exchange parameters. Principal component analysis (PCA) results explained the total variance into two principal components contributing the maximum (93.50 %) among the drought exposure with or without Se due to the various experiment indexes. In conclusion, Se exerts beneficial properties on drought-induced detrimental effects in G. macrophylla by relieving oxidative stress, improving photosynthesis indexes, PSII activity, regulating anatomical changes, altering levels of gentiopicroside and loganinic acid, and promoting growth of drought-stressed G. macrophylla.

Silicon and Seaweed Extract Injection into Olive Tree (Olea europaea L.) Trunks Results in the Tree’s Drought Stress Resistance

ABSTRACT Trunk injection applies more nutrients in the correct volume and composition, delivering ideal results with fewer fertilizer treatments under drought-stress conditions. We used a completely randomized block design to examine the effects of trunk injection therapy on the development of drought stress tolerance in olive trees in arid climates. Treatments included seaweed extract (SWE), potassium amino acid chelate (PAC), calcium silicate (CS), and potassium silicate (PS) at five different concentrations: 0.25, 0.5, 1, 2, and 4% for each treatment. Each treatment consisted of four replications – four dry replications for each treatment and four irrigation controls – each receiving weekly irrigation. The findings showed that, in comparison to drought control, trunk injection of PAC at a concentration of 2% enhances the relative water content of leaf and proline and decreases electrolyte leakage (EL) and malondialdehyde (MDA) content. Chlorophyll a, carotenoids, and proline content are all significantly higher in the trunk after CS injection at a 4% concentration than in the control treatment. MDA and EL were also reduced. Injecting PS leads to an increase in proline and photosynthetic pigments. The SWE treatment improved the proline, relative leaf water content, and photosynthetic pigments. To sum up, trunk injection treatments under drought conditions improved plant photosynthetic pigments, increased proline content, prevented relative water content reduction, and prevented an increase in MDA and EL. In conclusion, among the several treatments, the use of 2% PS was the most effective at reducing the adverse effects of drought stress on olive plants.

Level of Resistance of S1 Lines of Corn Plants to Drought Stress

The formation of hybrid varieties by self-crossing the F2 population has been carried out, thus obtaining the first generation selfing line (S1). This research aims to determine the level of drought stress resistance of S1 lines and corn plants and the correlation between their characters and the ISC value for each stress. The method used is an experimental method with field experiments. The experiment was carried out from March to June 2023 at the location in Gumantar Village, Kayangan District, North Lombok Regency. The experimental design used was a randomized block design (RAK) in a split plot design with the main plot consisting of stress and normal treatments, while the sub plots were the S1 lines and the F2 population. The results showed that there were different levels of resistance in the S1 line. G27 has resistance with tolerant criteria, 13 lines are moderately tolerant, and 16 other lines are susceptible; Correlation criteria between characters vary with the ISC value in each stress and normal condition. Characters that are strongly correlated with the ISC value are chlorophyll A, total chlorophyll, harvest dry cob weight, and dry kernel weight. The formation of S2 lines can be done using tolerant and moderately tolerant lines.