Physiomorphic and molecular-based evaluation of wheat germplasm under drought and heat stress

Drought and heat stress are potential problems that can reduce wheat yield, particularly during the terminal growth stages in arid and semiarid regions of the world. The current study intended to examine the impact of individual and combined drought and heat stress on the biochemical contents (antioxidant enzymes, proline, soluble proteins, and soluble sugars), physiological parameters (chlorophyll content, cell membrane stability, photosynthesis, stomatal conductance, and transpiration), plant–water relations (relative water content, water potential, osmotic potential, and pressure potential), agronomic traits (flag leaf area, plant height, number of tillers per plant, spike length, grains per spike, and thousand-grain weight), and gene expression (TaHSF1a, TaWRKY-33, TaNAC2L, and TaGASR1) in four different thermostable and drought-tolerant wheat genotypes (i.e., Gold-16, HS-240, Suntop, and Hemai-13) collected from different countries. The tri-replicate experiment was conducted using two factorial arrangements in a randomized complete block design (RCBD). All measured traits, except total soluble sugars, proline, and cell membrane stability index, showed significant reduction under both combined and individual treatments. Furthermore, correlation analysis revealed a significant association between biochemical and physiological characteristics and crop agronomic productivity. Furthermore, principal component analysis (PCA) and heatmap analysis demonstrated significant levels of variation in traits according to the type of stress and nature of wheat genotype. The spectrographs and micrographs generated by scanning electron microscopy for the selected high- and low- tolerance samples revealed clear differences in mineral distribution and starch granulation. All studied genes showed comparatively high levels of relative expression under combined treatments of drought and heat stress in all wheat genotypes, but this expression was the highest in ‘Gold-16’ followed by ‘HS-240’, ‘Suntop’, and ‘Hemai-13’. Overall, this study concluded that plants are proactive entities and they respond to stresses at all levels; however, the tolerant plants tend to retain the integrity of their biochemical, physiological, and molecular equilibrium

Enhancing Germination and Seedling Growth in Salt Stressed Maize Lines through Chemical Priming

This study aimed to investigate the tolerance level and the use of primers (H2O, KNO3, ascorbic acid and salicylic acid), in mitigating stress in maize in the newly released cultivars (SWAN-LSR-Y, BR9928-OMR-SR-Y and OMR-LSR-SY). Activities of SOD, APX, CAT and GSH and lipid peroxidation were investigated, to measure the biochemical response of the primed maize seeds. Maize seeds primed with KNO3 and ascorbic acid improved germination and anti-oxidative potential against ROS in ameliorating the salinity stress, while salicylic acid slowed germination. The same trend was followed in the seed vigour index and radicle length of seeds primed with ascorbic acid, which recorded the highest values. The control was observed to have the highest seed vigour index, while seeds primed with salicylic acid showed the least vigour index in the maize seeds.  Increased salinity stress showed adverse effects on all growth parameters. Of the maize cultivars tested, SWAN-LSR-Y showed the most tolerance to salinity stress, in terms of germination. Significant high enzymatic activities and lipid peroxidation were recorded in seeds primed with ascorbic acid and KNO3 show their importance in plant metabolic activities

Molecular Assessment of Genetic Diversity and Genetic Structure of Rhanterium epapposum Oliv. in Scarce Populations in Some Regions of Western Saudi Arabia

Rhanterium epapposum Oliv. is a perennial medicinal shrub growing mainly in desert habitats in the Arabian Peninsula. In western Saudi Arabia, the remaining few populations of this species are exposed to many threats, including overcutting, overgrazing, and recently, increasing human activities. These threats are predicted to be exacerbated by the advancement of aridification caused by climate change. The conservation and recovering of the diminished populations of R. epapposum necessitate measurement of their genetic diversity and genetic differentiation. To accomplish this objective, we tested 150 simple sequence repeat (SSR) primer pairs, with which 40 polymorphic loci were identified. These polymorphic loci were used to determine the population genetics of 540 plant accessions sampled from a total of 45 populations of R. epapposum located in 8 sites in western Saudi Arabia: Wadi Khurieba, Wadi Al Khamas, Gebel Al Twaal, Al Asaafer, Wadi ALHamda, Wadi Al Nassayeif, Wadi Qaraba, Wadi Kuliayah, and Wadi Dahban. Low levels of genetic diversity were found in all populations (the values of the PPL ranged between 52.5 and 15) along with a declined value of HT (0.123) and a considerable inbreeding value (F = 0.942), which confirmed a noticeable shortage of heterozygotes. High genetic differentiation among the populations and a low value of gene flow are indicative of high isolation among the R. epapposum populations, which has caused a severe deficiency in gene migration. The data obtained herein inspire several recommendations for conservation and retrieval of the existing populations, including seed banks, restoration of diminished populations, and monitoring and prevention of cutting and grazing activities at threatened sites. All of these measures are urgently required to avoid imminent extinction

Folic Acid Confers Tolerance against Salt Stress-Induced Oxidative Damages in Snap Beans through Regulation Growth, Metabolites, Antioxidant Machinery and Gene Expression

Although the effect of folic acid (FA) and its derivatives (folates) have been extensively studied in humans and animals, their effects are still unclear in most plant species, specifically under various abiotic stress conditions. Here, the impact of FA as a foliar application at 0, 0.1, and 0.2 mM was studied on snap bean seedlings grown under non-saline and salinity stress (50 mM NaCl) conditions. The results indicated that under salinity stress, FA-treated plants revealed a significant (p ≤ 0.05) increase in growth parameters (fresh and dry weight of shoot and root). A similar trend was observed in chlorophyll (Chl b), total chlorophyll, carotenoids, leaf relative water content (RWC), proline, free amino acids (FAA), soluble sugars, cell membrane stability index (CMSI), and K, Ca, and K/Na ratio compared to the untreated plants. In contrast, a significant decrease was observed in Na and salinity-induced oxidative damage as indicated by reduced H2O2 production (using biochemical and histochemical detection methods) and rate of lipid peroxidation (malondialdehyde; MDA). This enhancement was correlated by increasing the activities of antioxidant enzymes, i.e., superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX). Gene expression analyses conducted using qRT-PCR demonstrated that genes coding for the Na+/H+ antiporter protein Salt Overly Sensitive 1 (SOS1), the tonoplast-localized Na+/H+ antiporter protein (NHX1), and the multifunctional osmotic protective protein (Osmotin) were significantly up-regulated in the FA-treated plants under both saline and non-saline treatments. Generally, treatment with 0.2 mM FA was more potent than 0.1 mM and can be recommended to improve snap bean tolerance to salinity stress

Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia

To assess trace element concentrations (Zn, Cu, Pb, Cr, Cd and Ni) in the mangrove swamps along the Saudi coast of the Arabian Gulf, thirteen samples of surface sediment and leaves of grey mangrove, Avicennia marina were collected and analyzed. The detected trace element contents (μg g-1) in surface sediments were in the following descending order according to their mean values; Cr (49.18) > Zn (48.48) > Cu (43.06) > Pb (26.61) > Ni (22.88) > Cd (3.21). The results showed that the average concentrations of Cd and Pb exceeded their world average concentration of shale. The geo-accumulation, potential ecological risk and toxicity response indices demonstrated that trace elements have posed a considerable ecological risk, especially Cd. The inter-relationships between physico-chemical characters and trace elements suggests that grained particles of mud represent a noteworthy character in the distribution of trace elements compared to organic materials. Moreover, the results revealed that Zn was clearly bioaccumulated in leaf tissues A. marina. Dredging, landfilling, sewage effluents and oil pollution can be the paramount sources of pollution in the area under investigation

De Novo Transcriptome Analysis of <i>Solanum lycopersicum</i> cv. Super Strain B under Drought Stress

Tomato cv. super strain B was widely cultivated in Saudi Arabia under drought stress. Illumina Hiseq-2000 was used to create the transcriptional profile of tomato cultivar super strain B. A total of 98,069 contigs were gathered, with an average length of 766 bp. Most of the genes in the gene ontology (GO) analysis were categorized into molecular function (MF) of ATP binding (1301 genes), metal ion binding (456 genes), protein kinase activity (392 genes), transferase activity (299 genes), Biological process (BP) of DNA-templated genes (366 genes), and regulation of transcription genes (209 genes), while cellular components (CC) of integral component of membrane (436 genes). The most dominant enzymes expressed were transferases (645 sequences). According to the KEGG pathway database, 15,638 transcripts were interpreted in 125 exclusive pathways. The major pathway groups were metabolic pathways (map01100, 315 genes) and biosynthesis of secondary metabolites (map01110, 188 genes). The total number of variants in the twelve chromosomes of super strain B compared with the tomato genome was 5284. The total number of potential SSRs was 5047 in 4806 unigenes. Trinucleotide repeats (3006, 59.5%) were the most found type in the transcriptome. A total of 4541 SNPs and 744 INDELs in tomato super strain B were identified when compared with the tomato genome

Zinc Supplementation Enhances Glutathione-Mediated Antioxidant Defense and Glyoxalase Systems to Conferring Salt Tolerance in Soybean (<i>Glycine max</i> L.)

In this study, the role of zinc (Zn) in salt-affected soybean (Glycine max L.) was scrutinized by exposing plants to salt stress (150 mM NaCl) alone and in combination with exogenous Zn (priming and/or foliar spray with 1 mM ZnSO4.7H2O). Salt stress decreased plant growth and caused the destruction of chlorophyll and carotenoids. It also disrupted physiological processes and antioxidant defenses, resulting in an oxidative burst. The levels of the toxic metabolite methylglyoxal (MG) rose substantially under salinity. Salinity resulted in a high accumulation of Na+ and decreased K+ which decreased the K+/Na+ ratio. Zn supplementation decreased ion toxicity and improved ion homeostasis in soybean plants. Zn increased glutathione (GSH) levels, decreased glutathione disulfide levels, and increased their ratio in salt-treated soybean plants compared to salt-treated plants without Zn addition. Zn supplementation also upregulated the activities of the glutathione-dependent enzymes glutathione reductase, dehydroascorbate reductase, glutathione peroxidase, and glutathione S-transferase in salt-stressed plants. The enhanced GSH pool and increased activity of GSH-dependent enzymes decreased oxidative damage, as indicated by the reduced levels of H2O2 and malondialdehyde and lower electrolyte leakage. The increased GSH level and high activity of glyoxalase I and glyoxalase II conferred by Zn under salt stress helped to scavenge methylglyoxal. The restoration of photosynthetic pigment levels and increased proline accumulation, together with the recovery of leaf relative water content, were further signs of salt stress recovery and tolerance conferred by Zn supplementation. Our results showed that the antioxidant defense, glyoxalase system and some other physiological parameters were improved by Zn supplementation which contributed to mitigating the effects of salt stress in soybean

Zinc Supplementation Enhances Glutathione-Mediated Antioxidant Defense and Glyoxalase Systems to Conferring Salt Tolerance in Soybean (Glycine max L.)

In this study, the role of zinc (Zn) in salt-affected soybean (Glycine max L.) was scrutinized by exposing plants to salt stress (150 mM NaCl) alone and in combination with exogenous Zn (priming and/or foliar spray with 1 mM ZnSO4.7H2O). Salt stress decreased plant growth and caused the destruction of chlorophyll and carotenoids. It also disrupted physiological processes and antioxidant defenses, resulting in an oxidative burst. The levels of the toxic metabolite methylglyoxal (MG) rose substantially under salinity. Salinity resulted in a high accumulation of Na+ and decreased K+ which decreased the K+/Na+ ratio. Zn supplementation decreased ion toxicity and improved ion homeostasis in soybean plants. Zn increased glutathione (GSH) levels, decreased glutathione disulfide levels, and increased their ratio in salt-treated soybean plants compared to salt-treated plants without Zn addition. Zn supplementation also upregulated the activities of the glutathione-dependent enzymes glutathione reductase, dehydroascorbate reductase, glutathione peroxidase, and glutathione S-transferase in salt-stressed plants. The enhanced GSH pool and increased activity of GSH-dependent enzymes decreased oxidative damage, as indicated by the reduced levels of H2O2 and malondialdehyde and lower electrolyte leakage. The increased GSH level and high activity of glyoxalase I and glyoxalase II conferred by Zn under salt stress helped to scavenge methylglyoxal. The restoration of photosynthetic pigment levels and increased proline accumulation, together with the recovery of leaf relative water content, were further signs of salt stress recovery and tolerance conferred by Zn supplementation. Our results showed that the antioxidant defense, glyoxalase system and some other physiological parameters were improved by Zn supplementation which contributed to mitigating the effects of salt stress in soybean

Evaluation of nano-nitrogen fertilizers and other nitrogen sources on the performance of Guinea grass plants grown in newly reclaimed soil under water deficiency

Water deficiency and chemical fertilizers' pollution are two of many factors causing imbalance in the ecosystem rhythm, which reflects on farm livestock quality and quantity, particularly in arid and semi-arid regions. Limited research is available on the use of different sources of nitrogen fertilizers on pasture crops; hence, an open field research experiment was carried out in newly reclaimed soil to investigate the effect of different sources of nitrogen fertilizers on maximizing protein level and production of Guinea grass (Panicum maximum Jacq.) plant under water deficiency. Present data from two successive seasons revealed that: plants received nitrogen in the form of nano particles recorded significant increases in yield, morphological parameters, leaf anatomy, and chemical composition (macro and micro nutrients, total carbohydrates, plant pigments and crude protein) over control (plants that received the recommended dose of NPK fertilizers) in both growing seasons. In addition, endogenous hormones; gibberellins (GA3) and abscisic acid (ABA) beside enzymes; superoxide dismutase (SOD) and peroxidase (POD) had been affected by different treatments. The lowest amounts of cellulose, hemicellulose and lignin were resulted from nitrogen nano particles treatment, while the rates of leaf photosynthesis, stomatal conductance, intercellular CO2 concentration, and water use efficiency were enhanced also by nitrogen nano particles treatment application. The present findings suggested that increasing crude protein level of Guinea grass plant grown in newly reclaimed soil by addition of the mentioned nanoparticles could be a promising approach to improve crop productivity under water deficiency and reduce environmental pollution

Determination of ROS Scavenging, Antibacterial and Antifungal Potential of Methanolic Extract of Otostegia limbata (Benth.) Boiss.

Wide spectrum medicinal significance augments plant utilization as the primary source of significant pharmaceutical agents. In vitro investigation of antioxidant and antimicrobial activity highlights the therapeutic potential of Otostegia limbata. Methanol extract of the plant (MEP) shows considerable dose dependent antioxidant ability at six concentrations (7.81 µg/mL to 250 µg/mL) in 2.2-diphenyl-1-picrylhydrazyl (DPPH) assay, phosphomolybdate assay (PMA) and reducing power assay (RPA). The plant capability to scavenge free radicals in the mixture ranged from 37.89% to 63.50% in a concentration-dependent manner. MEP was active against five tested bacterial strains in the agar-well diffusion method. Staphylococcus aureus, gram-positive bacteria was found to be most susceptible followed by S. epidermidis with 18.80 mm and 17.47 mm mean zone of inhibition. The mean inhibition zone against gram-negative strains Klebsiella pneumonia, Pseudomonas spp. and Escherichia coli were 15.07 mm, 14.73 mm, and 12.17 mm. MEP revealed potential against Alternaria spp. and Aspergillus terreus fungal strains evaluated through agar-tube dilution assay. Aspergillus terreus was more sensitive than Alternaria spp. with an average 78.45% and 68.0% inhibition. These findings can serve as a benchmark for forthcoming scrutiny such as bioactive components discovery and drug development