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Changes in the metabolic profile within the intestine of lenok (Brachymystax lenok) when challenged to acute and lethal heat stress (HS) are studied using no-target HPLC-MS/MS metabonomic analysis. Of 51 differentially expressed metabolites identified in response to HS, 34 occurred in the positive ion mode and 17 in negative ion mode (VIP > 1, P < 0.05). Changes in metabolites (i.e. alpha-D-glucose, stachyose and L-lactate) related to carbohydrate and glycolysis are identified in HS-treated lenok. Fatty acid β-oxidation in HS-treated lenok was inhibited by accumulation of acetyl carnitine, palmitoylcarnitine, carnitine, and erucic acid. Many amino acids (L-tryptophan, D-proline, L-leucine, L-phenylalanine, L-aspartate, L-tyrosine, L-methionine, L-histidine and L-glutamine) decreased to support energy demands in HS-treated lenok. Oxidative damage in HS-treated lenok was indicated by decreased glycerophospholipid metabolites (i.e. glycerophosphocholine, 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphoethanolamine, 1-palmitoyl-sn-glycero-3-phosphocholine, 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine, and 1, 2-dioleoyl-sn-glycero-3-phosphatidylcholine), and increased oxylipin production (12-HETE and 9R, 10S-EpOME). Oxidative stress increased formation of eicosanoids and dicarboxylic acids, overwhelming the mitochondrial β-oxidation pathway, while minor oxidative pathways (omega-oxidation and peroxisomal beta-oxidation) were likely to be activated in HS-treated lenok.

A 56-day experiment was conducted to investigate the effects of ambient salinity and alkalinity on fatty acids, free amino acids and related anabolic metabolisms of Nile tilapia. The fatty acid and free amino acid contents in the muscle of tilapia cultured in saline water (SW), alkaline water (AW), saline–alkaline water (SAW) and fresh water (FW) conditions were analyzed and compared. The mRNA levels and enzymatic activities of fatty acyl desaturase (FADS2), elongation of very long-chain fatty acids (ELOVL5), Δ1-pyrroline-5-carboxylate synthase (P5CS), ornithine-δ-aminotransferase (δ-OAT), and proline dehydrogenase (PDH) were also determined. The contents of saturated and monounsaturated fatty acids were significantly higher in the AW and SAW groups than those in the SW group, and those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were the highest in the SAW group. The contents of flavor amino acids in the SAW and AW groups were significantly higher than that in the SW group, and that of proline in the SW, AW, and SAW groups was 3.58-, 4.11-, and 4.15-times higher than that in the FW group. The mRNA levels and enzyme activities of FADS 2, ELOVL5, PDH and P5CS were found to differ among the different groups. The results suggested that ambient salinity and alkalinity could effectively improve flesh quality of tilapia by regulating lipid and proline metabolism pathways.

Drought and salinity are major environmental stresses that impair crop growth and productivity worldwide. Improving drought and salt tolerance of crops with microbial mutualists is an effective and environmentally sound strategy to meet the demands of the ever-growing world population. In the present study, we found that the Streptomyces albidoflavus OsiLf-2, a moderately salt-tolerant endophytic actinomycete, produced abundant osmolytes, including proline, polysaccharides, and ectoine. Inoculation with OsiLf-2 increased the osmotic-adjustment ability of the rice host by increasing the proline content (by 250.3% and 49.4%) and soluble sugar (by 20.9% and 49.4%) in rice under drought and salt conditions, relative to the uninoculated control. OsiLf-2 increased stress responses in the rice host at the physiological and biochemical levels (photosynthesis efficiency, osmolytes and antioxidant content), and the gene level (osmolytes synthesis, stress-responsive and ion-transport related genes), raising rice yields under both greenhouse and saline–alkaline soil conditions. The use of endophytic actinomycetes offers a promising biotechnological approach to developing stress-tolerant plants.

Drought stress adversely affects plant health and productivity. Recently, drought-resistant bacterial isolates are used to combat drought resistance in crops. In this in vitro study, 20 bacterial isolates were isolated from harsh soil; their drought tolerance was evaluated using four concentrations of polyethylene glycol (PEG) 6000. The two most efficient isolates (DS4 and DS9) were selected and identified using 16S rRNA genetic sequencing. They were registered in the NCBI database and deposited under accession numbers MW916285 and MW916307 for Bacillus cereus (DS4) and Bacillus albus (DS9), respectively. These isolates were screened for plant growth-promoting properties compared to non-stressed conditions. Biochemical parameters; Proline, salicylic acid, gibberellic acid (GA), indole acetic acid (IAA), antioxidant activity, and antioxidant enzymes were measured under the same conditions, and in vitro seed germination was tested under stress conditions and inoculation with selected isolates. The results showed that under the harsh conditions of PEG6000, DS4 produced the highest amount of IAA of 1.61 µg/ml, followed by DS9 with 0.9 µg/ml. The highest amount of GA (49.95 µg/ml) was produced by DS9. On the other hand, the highest amount of siderophore was produced from DS4 isolate followed by DS9. Additionally, DS4 isolate recorded the highest exopolysaccharide (EPS) content of 3.4 mg/ml under PEG (-1.2 MPa) followed by DS9. The antioxidant activity increased in PEG concentrations depending manner, and the activity of the antioxidant enzymes increased, as catalase (CAT) recorded the highest activity in DS4 with an amount of 1.095 mg/ml. additionally, an increase in biofilm formation was observed under drought conditions. The isolated mixture protected the plant from the harmful effects of drought and showed an increase in the measured variables. Under unstressed conditions, the highest rates of emulsification index (EI 24%) were obtained for DS4 and DS9, at 14.92 and 11.54, respectively, and decreased under stress. The highest values of germination, total seedling length, and vigor index were obtained upon inoculation with the combination of two strains, and were 100%, 4.10 cm, and 410, respectively. Therefore, two strains combination is an effective vaccine capable of developing and improving drought tolerance in dryland plants.

Rain-fed fig culture is known to provide a good quality of dried figs, while almost no research has been reported so far on the enzyme activity comparisons of seasonal variations among terminal buds in this plant. Toward this goal, we evaluated the physiochemical changes of terminal buds of fig 'Sabz' and their micromorphology during the dormant season (November to April) using Scanning Electron Microscope (SEM) analysis during two consecutive years (2016 and 2017). Results indicated that the highest contents of total sugars in terminal fig buds were registered in January and the lowest values were noticed in April. SEM analysis showed the presence of vegetative terminal fig buds during the dormant season and after bud-break in April. An increasing trend was observed for the protein content, length and diameter of terminal buds at the beginning of bud-break. In dormant buds, ascorbate peroxidase, peroxidase and catalase enzymes exhibited initially an ascending pattern, while it decreased from December. A second increase for these enzymes occurred during the dormant season until bud-break. Superoxide dismutase activity increased in buds during the dormancy season until bud-break. Proline content remained stable in buds from November to February, while it decreased rapidly until bud-break. Furthermore, a downward trend of the total phenol content in buds was observed between the onset and end of dormant period. In general, the dormant buds in ʻSabzʼ fig cultivar were metabolically active with a short dormant period under the rain-fed conditions.

Maintaining a proper content of selenium (Se) in food is particularly important for human health. However, the mechanisms of uptake and enrichment of Se ENMs in crops are still unclear. Herein, Se engineered nanomaterials (Se ENMs) (size 62.3 ± 14.6 nm and surface charge −34.4 ± 1.4 mV) were synthesized and used as nanofertilizers for Se-fortified vegetables. The results demonstrated the Se content and yield were increased by 338.0% and 19.8% respectively in Brassica chinensis L. through soil application of Se ENMs (0.5 mg‧kg–1). The content of Se in vegetables increased up to 32.8 μg/100 g (7.5 μg/100 g for the control), which could provide the daily recommended Se intake (55–400 μg/day) for human. Amendments of the slightly alkaline soil with the Se ENMs improved beneficial rhizosphere microbiomes (Pseudomonas and Bacillus), and resulted in the plants accumulating more low molecular weight compounds (betaine, proline, glycine, norleucine, urocanic acid and indole-3-acrylic acid) with increases in the Se content of the plant by 264.9%. Moreover, the nutrient accumulation in leaves promoted the photosynthesis (16.7%) and increased carbohydrate content (6.5%). Also, the expression of carbohydrate transport-related genes (BnSUC1,1, BnSUC1,4, and BnSWEET10,2) were up-regulated by 52.2, 53.2 and 76.3-fold, respectively, promoting root growth, improving rhizosphere microbiome and nutrient availability. Therefore, such mutual benefits between leaves and roots using ENMs could provide an alternative model for cultivating Se-enriched crops.

Proline is a multifunctional amino acid that is accumulated in high concentrations in plants under various stress conditions. Proline accumulation is intimately connected to many cellular processes, such as osmotic pressure, energy status, nutrient availability, changes in redox balance, and defenses against pathogens. Proline biosynthesis and catabolism is linked to photosynthesis and mitochondrial respiration, respectively. Proline can function as a signal, modulating gene expression and certain metabolic processes. We review important findings on proline metabolism and function of the last decade, giving a more informative picture about the function of this unusual amino acid in maintaining cellular homeostasis, modulating plant development, and promoting stress acclimation.

Abscisic acid (ABA) and Selenium (Se) have been reported to alleviate the effect of abiotic stress especially drought in several plant species. Thus, this study aimed to compare the influence of foliar spray of ABA (0 and 100 µM) and Se (0 and 50 µM) on tomato plants grown under simulated drought stress at 0% soil field capacity (SFA). The obtained results based on physiochemical and antioxidant mechanism involving defense enzymes such as catalase, superoxide dismutase, ascorbate peroxidase and glutathione reductase revealed that ABA was potentially restrained drought stress in tomato plants compared to Se. ABA treatment significantly improved the relative water content and chlorophyll levels of seedlings compared to control. This represents the essential role of ABA on stress retrieval under drought conditions. In addition, ABA treated plants unveiled less hydrogen peroxide compared to control plants. This indicates the enhanced antioxidant mechanisms in ABA treated plants which consequently neutralized the hydrogen peroxide. In contrast, proline level was decreased in treated plants compared to control showed the diminished oxidative stress which simultaneously reduced the accumulation of proline. Overall, ABA protected tomato seedlings from the drought induced oxidative stress and promoted plant growth and development. Therefore, the present study suggests that the ABA foliar spray is more preferable to enhance the vegetative growth of tomato plants under water deficit condition.

Drought stress is one of the most important factors of physiological stress and the major constraint on crop productivity which limits plant growth and metabolism. The goal of this work was to study the differential response of groundnut genotypes to drought stress at the physiological, biochemical, and molecular levels during summer in the field. Thirty days old seedlings of six genotypes of groundnut viz. Kadiri 9, Narayani, Dharani, JL24, TPT-3, and Kadiri 6 were subjected to drought stress by withdrawing irrigation for 15 days. The results suggested a significant influence of drought stress on the physiological and biochemical levels in all the groundnut genotypes. A substantial decrease for physiological parameters viz. membrane stability index, chlorophyll stability index, and relative water content was observed under moderate and severe stress conditions compared to control across all genotypes. The high proline accumulating genotypes also exhibited lower lipid peroxidation under all stress periods. In Kadiri 9, Narayani, and Dharani genotypes, the antioxidant enzyme activity of superoxide dismutase, catalase, peroxidase, and glutathione reductase was significantly higher than JL24, TPT-3, and Kadiri 6 genotypes under all stress regimes. Among the genotypes tested, Kadiri 9, Narayani, and Dharani retained higher growth, yield, and seed quality characteristics showing tolerance for drought stress. qPCR analysis revealed stress-responsive existence of the selected genes, heat shock protein 70 (HSP70), dehydration-responsive element binding-2A (DREB2A), and no apical meristem, ATAF1/2, cup-shaped cotyledon 2 (NAC4) with 30 fold increase in the level of expression in Kadiri 9 compared to Kadiri 6.

Crop plants all over the world face an array of environmental threats among which drought is found to be the most deleterious. The present investigation was carried to test the efficacy of exogenously supplemented sodium nitroprusside (SNP), a nitric oxide donor, and polyamine (PA) putrescine (PUT) in mitigating the effects of polyethylene glycol (PEG)-imposed drought stress in in vitro grown seedlings of Solanum lycopersicum. PEG treatments at different concentrations (1, 2, 5, 10, and 15%) were assessed for their impact on plant growth parameters based on which 10% PEG was chosen as effective drought treatment. Varying concentrations of SNP (100, 150, and 200 µM) and PUT (0.1, 0.3, and 0.5 mM) at different combinations were studied for their mitigating effects. The results revealed that among the combinations tested, SNP (150 µM) + PUT (0.3 mM) resulted in effective mitigation of drought stress in S. lycopersicum seedlings. SNP and PUT supplementation enhanced the growth parameters such as shoot and root length and plant fresh weight (FW). Further, the relative water content (RWC), chlorophyll, and proline contents were significantly enhanced in the experimental plants as compared to the control. Effective reduction in the malondialdehyde (MDA) and hydrogen peroxide (H2O2), a significant increase in the antioxidant enzymes, and the transcriptional level upregulation of antioxidant genes and drought-responsive genes were observed in the treated plants as compared to the control. These results suggest that exogenous supplementation of SNP and PUT has a positive influence on alleviating the drought stress in S. lycopersicum.

Salinity stress is one of the most important global problems that afflicts and limits the growth and development of turfgrass in arid and semi-arid areas. Therefore, this experiment was conducted to evaluate the effects of the interaction between gamma-aminobutyric acid (GABA) and salinity (NaCl) on perennial ryegrass (Lolium perenne L.). Perennial ryegrass plants were treated with three concentrations of GABA (0, 50, and 100 mM) and NaCl (0, 50, and 100 mM) for two months. Multivariate analysis of variance revealed that GABA, salinity, and their interaction had significant effects on the majority of measured traits. In shoots and roots, the application of salinity increased the Na+/K+ ratio, as well as proline, total soluble carbohydrates and protein (TSP), malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, but reduced relative water content, membrane stability index (MSI), total chlorophyll content, and shoot and root growth. When GABA was applied in saline conditions, Na+ did not accumulate, the Na+/K+ ratio decreased, and the amount of K+ content increased significantly in shoots and roots, thereby allowing plant growth to resume. Peroxidase (POD) and superoxide dismutase (SOD) activities increased significantly (51.83% and 322%, respectively), whereas H2O2 and MDA contents decreased significantly (34.4% and 67%, respectively). In addition, the construction of a biplot, heatmap, and correlation plot fortified the positive effects of GABA on perennial ryegrass growth in saline conditions. GABA may help to alleviate salinity damage through its involvement in osmotic adjustment (proline and TSP), reducing the Na+/K+ ratio and limiting oxidative damage in cells with a dramatic increase in POD and SOD activity. Therefore, the application of GABA is an alternative technique for improving turfgrass tolerance to salinity.

A pot experiment was carried out in at Agricultural Research Station, Agricultural Research Center, Giza Governorate, Egypt, (latitude 26o 31′N and longitude 31o 11′E) during 2019 and 2020 seasons to compare two sugarcane promising clones, with the commercial variety GT.54-9 (Saccharum spp. L.), under three irrigation water levels (60, 80 and 100% of IWL). A randomized completely design with five replications was used. Some growth traits such as shoot and root FW, root/shoot ratio, leaf area index (LAI), leaf area ratio (LAR), as well as the biochemical constituents like chlorophylls, carotenoids, proline, total soluble sugars, total amino acids, total soluble proteins and macronutrients i.e. N, P, K, Mg and Ca were assessed. Results showed that, clone 2 had the desirable values for the studied traits more than the commercial variety GT.54-9, while the clone1 recorded undesirable values for the studied traits compared to commercial variety GT.54-9 under water deficit stress that be contributed. So could be select the line 2 as anew promising variety in sugar cane cultivar with drought tolerance. In addition to, sugarcane studied clones not affected by increase the degree of IWL from 80 to 100%.

NMR-based metabolic profiling of polar extracts of somatic embryogenic and organogenic cultures of the medicinal plant Cymbopogon schoenanthus subsp. proximus were studied. Regeneration through somatic embryogenesis was done on media containing 2,4-D and BAP while organogenesis was achieved on media containing NAA and BAP. Fifty-two metabolites were identified in embryogenic calli (EC), organogenic calli (OC), regenerated embryogenic shoots (ES), and organogenic shoots (OS). Chemometrics and cluster analysis were used to depict the correlation between the groups investigated. Metabolic profiles revealed unique metabolites in ES (serine and lactate) and in OS (2-hydroxyisobutyrate, tyrosine, histamine and homoserine). Quantitative differences as manifested by relative concentrations through heat map and fold change analyses were significant in the following comparisons: calli type, embryogenic tissues, organogenic tissues, and shoot type. In a comparison of calli types, proline, asparagine and arginine were upregulated in EC and sucrose was upregulated in OC. When comparing embryogenic tissues, monosaccharides were upregulated in EC, while proline, pyroglutamate and 4-aminobutyrate were upregulated in ES. Upon comparison of organogenic tissues, trigonelline increased by 17-fold in OS; however, monosaccharides were upregulated in OC. Finally, when comparing shoot types, 4-aminobutyrate, betaine and proline were upregulated in ES, while mono- and disaccharides were upregulated in OS. The embryogenic system was characterized by accumulation of stress related metabolites (proline); however, glycolate was identified only in the organogenesis system. The present work contributes to the understanding of the metabolic characteristics and differences between the two regeneration systems as manifested by profiles of EC, OC, and their regenerated shoots. Metabolic characteristics of two regeneration systems (somatic embryogenesis and organogenesis) of Cymbopogon schoenanthus were examined using NMR-based profiles of calli and their regenerated shoots, revealing clear qualitative and quantitative differences between the two systems at the studied developmental stages.

The covalent attachment of ubiquitin to proteins plays a fundamental role in the regulation of cellular function through biological events involving abiotic or biotic stress responses, immune responses, and apoptosis. Here, we characterize the biological function of the Arabidopsis thaliana RING Zinc Finger 1 (AtRZF1) in dehydration response. AtRZF1 was significantly reduced by drought stress. The atrzf1 mutant was less sensitive to osmotic stress than the wild-type during early seedling development, whereas transgenic plants overexpressing AtRZF1 were hypersensitive, indicating that AtRZF1 negatively regulates drought-mediated control of early seedling development. Moreover, the ectopic expression of the AtRZF1 gene was very significantly influential in drought sensitive parameters including proline content, water loss, membrane ion leakage and the expression of dehydration stress-related genes. AtRZF1 is a functional E3 ubiquitin ligase, and its conserved C3H2C3-type RING domain is likely important for the biological function of AtRZF1 in drought response. Together, these results suggest that the E3 ligase AtRZF1 is an important regulator of water deficit stress during early seedling development.

In this study, the effects of exogenous hydrogen sulfide (H2S) treatments on eggplant seedlings were examined under salt stress. This study was a pot study carried out under controlled greenhouse conditions with three salt levels (0, 50 and 100 mM NaCl) and four H2S doses (0, 25, 50 and 100 µM NaHS). Plant growth parameters, chlorophyll content, membrane permeability (MP), leaf relative water content (LWRC), photosynthetic properties, hydrogen peroxide (H2O2), proline, malondialdehyde (MDA), sucrose, and antioxidant enzymes (catalase (CAT) and superoxide dismutase (SOD)) activity, abscisic acid (ABA) and minerals content of eggplant seedling were examined. Plant growth properties were decreased with salinity. However, H2S application alleviated the effect of salt stress on these parameters. Membrane permeability increased with salt stress, but was lower in H2S treatments than non- H2S treatment. Salt stress significantly decreased LWRC, stomatal conductance (gs), net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), transpiration rate (Tr) and chlorophyll properties. With H2S treatments, these decreasing were lower. Hydrogen peroxide, MDA, proline and sucrose content increased compared to the control, but H2O2, MDA, proline and sucrose content of eggplant seedlings decreased with H2S treatment under salt stress. Furthermore, CAT and SOD increased with different salt levels. However, CAT and SOD activity decreased with H2S treatments under salt stress. ABA content increased significantly with salinity, but ABA content decreased with H2S treatments under salt stress conditions. Similarly, the mineral content of leaf and root of eggplant seedlings were decreased under salt stress (except for Na and Cl), the decrease of mineral content was lower with H2S treatments. Effect in alleviating of the H2S on salt stress damage can explained by regulation of enzyme activity and mineral uptake, low level of ABA and the minimization of reactive oxygen species (ROS) damage by accumulation of osmolytes.

The cellular glucose level has to be tightly regulated by a variety of cellular processes. One of them is the degradation of gluconeogenic enzymes such as Fbp1, Icl1, Mdh2, and Pck1 by GID (glucose-induced degradation deficient) E3 ubiquitin ligase. The Gid4 component of the GID ligase complex is responsible for recognizing the N-terminal proline residue of the target substrates under normal conditions. However, an alternative N-recognin Gid10 controls the degradation process under stressed conditions. Although Gid10 shares a high sequence similarity with Gid4, their substrate specificities are quite different. Here, we report the structure of Gid10 from Saccharomyces cerevisiae in complex with Pro/N-degron, Pro-Tyr-Ile-Thr, which is almost identical to the sequence of the natural substrate Art2. Although Gid10 shares many structural features with the Gid4 protein from yeast and humans, the current structure explains the unique structural difference for the preference of bulky hydrophobic residue at the second position of Pro/N-degron. Therefore, this study provides a fundamental basis for understanding of the structural diversity and substrate specificity of recognition components in the GID E3 ligase complex involved in the Pro/N-degron pathway.

Juniperus excelsa is one of the most common tree species and has a wide geographical and altitudinal distribution in Turkey. It is also resistant to drought and frost damages and can cope with poor soils. In this study, we explore whether there are any differences among eight J. excelsa populations from a narrow geographic region grown in a common garden test site in terms of growth and contents of photosynthetic pigments, proline and nutrients of their 10-year-old saplings. Phenotypic trait differentiation (QST) at all traits, FST at neutral SSRs among six of the populations and associations of traits with environmental conditions at provenance regions were also analysed to test for patterns of local adaptation. Sapling traits of eight J. excelsa populations of from Lakes District in Turkey at the test site showed that populations significantly differed for growth, photosynthetic pigments, proline and nutrient contents. The mean height and diameter of 10-year-old saplings were found as 94.5 cm and 41.6 mm, respectively. Egirdir-Barla and Sutculer-Tota populations showed the highest performance for the majority of traits at age 10 compared to all other populations. Nutrient contents in leaves were generally in the sufficiency range reported for plant growth. Considering photosynthetic pigments and proline, it could be concluded that the populations were not exposed to severe stress. Among the environmental variables, the best predictors of growth were annual mean minimum temperature and soil texture at the populations’ origin, accounting for 49% of the variation in height and diameter, respectively. Also, higher phenotypic trait differentiation for most traits than genetic differentiation at neutral genetic markers suggests local adaptation at a small geographic scale. The present study revealed adaptive divergence between populations at a small geographic scale. However, environmental similarity between region of origin and test site was not a good indicator of growth-related traits. The results can be used in the early selection of provenances for J. excelsa for plantation establishment.

Tissue culture methods are useful in assessing the tolerance of various stresses due to the ease of controlling stress under in vitro conditions. This study aimed to investigate the response of sugarcane genotyps to drought stress using calli as a model system. For inducing sugarcane callus, the medium of Murashige and Skoog (MS) was used with different mannitol concentrations (100, 200, and 300 mM) to measure their effects on callus frequency, the day of callus initiation, embryogenic potential, relative growth rate (RGR), water and proline contents, K+ and Na+ contents, as well as the formation of shoot and roots for three sugarcane genotypes (e.g., GT 54-9, G 84-47, and pH 8013). The RAPD-PCR analysis was carried out using five oligonucleotide primers to identify the genetic variation among sugarcane genotypes. The results indicated that the degree of callus proliferation varied from 70 − 86%. The highest value of callus proliferation, PGR, shoot formation was recorded for the genotype GT 54-9 compared to the other two genotypes (G 84-47 and pH 8013). Calli treated with 100 mM mannitol showed the highest RGR, proline and waer contents for the genotype GT 54-9, while, those treated with 300 mM recorded the lowest values of these parameters for the genotype pH 8013. The genotype G 84-47 collected highest Na+ content, while the genotype pH 8013 collected highest K+ content. The results of this study recommend preference for GT 54-9 genotype, which is considered the most promising genotype, showing more tolerance to drought stress based on all studied traits.

Background Cocoa, being a shade loving crop cannot withstand long periods of water stress. Breeding for drought tolerance is the need of the hour due to change in climatic condition and extension of crop to non-traditional areas. Hybrids were produced by crossing four tolerant genotypes in all possible combination. The cross GV1 55 x M 13.12 didn’t yield any fruit due to cross incompatibility between these genotypes. Various biochemical parameters act as the true indicators to select tolerant and susceptible types. The major biochemical parameters considered after imposing stress included proline, nitrate reductase activity, superoxide dismutase content and glycine betaine. Results The drought tolerant hybrids were having high amount of proline, superoxide dismutase enzyme and glycine betaine content. Normally, plants having drought stress show low amount of nitrate reductase activity. However, in case of hybrids, the drought tolerant hybrids were having higher NR activity than the susceptible hybrids. The highest amount of NR was found in the control plants kept at fully irrigated conditions. Conclusions This experiment showed the role of different biochemical enzymes and osmolytes in giving tolerance to plants during drought stress. Logistic regression analysis selected proline and nitrate reductase as the two biochemical markers for identifying efficient drought tolerant genotypes in the future breeding programmes.

Compound-specific stable isotope analysis of individual amino acids (AAs) has been widely used in studies on food webs, resource tracing, and biochemical cycling. In the present study, juvenile sea cucumbers Apostichopus japonicus were fed the microalga Cylindrotheca fusiformis (CF) or Sargassum thunbergii (ST) during a 130-day experiment. The δ13C values of individual AAs in the experimental diet and body wall of sea cucumbers were determined to calculate the variability in carbon isotopic fractionation (Δ13C) and elucidate the isotopic routing of essential AAs and biosynthesis of nonessential AAs. The results showed that the sea cucumbers fed with diet CF had higher specific growth and ingestion rates but relatively lower feed conversion efficiency compared to those fed with diet ST. The experimental diets were generally less abundant in nonessential AAs (i.e., glycine, serine, aspartic acid, and arginine) but more abundant in essential AAs (i.e., isoleucine, leucine, lysine, phenylalanine, and histidine) than body walls. The fluctuations in the δ13C values of total AAs analyzed were 19.8 ± 4.6‰ for diets and 21.3 ± 2.7‰ for body walls. Serine and threonine were 13C-enriched AAs, while leucine and phenylalanine were 13C-depleted AAs. The diet ST treatment exhibited more positive Δ13C values of nonessential AAs (e.g., glycine, alanine, aspartic acid, and proline) compared to diet CF. There were significant negative relationships between Δ13C values and differences in nonessential AA percent abundance between the experimental diets and body walls of sea cucumber (for diet CF: y = -0.79 - 0.56x, r2 = 0.47; diet ST: y = 0.75 - 0.29x, r2 = 0.51), which implied the flexibility in the routing of various dietary macronutrients (protein, lipids, and carbohydrates) by sea cucumber. This study can greatly provide a new understanding of nutrient utilization and metabolism routing during juvenile sea cucumber culturing.

The study was conducted to determine sesame seed capsules' proximate composition, amino acid, and phytochemical properties as a potential feed resource. Homogeneous triplicate representative samples were analyzed following scientific protocols. The results indicated that the sesame seed capsule contained 75.41% carbohydrate, 3.59% ether extract, 4.32% protein, 93.57% dry matter, 12.01% crude fiber, and 4.77% ash. The amino acids profile showed glutamic acid with the highest value of 1.71, while proline was not found. The phytochemical contents of the seed showed the presence of alkaloid (1209.88 mg/100 g, phytate (41.07 mg/100 g), saponin (31.94 mg/100 g), oxalate (3.33 mg/100 g), and trypsin inhibitor (9.92 Tiu/mg/g), respectively. The crude fiber and energy values indicated it was a good source of fiber and energy; however, the protein quality was poor, and the concentration of alkaloid, trypsin inhibitor, and oxalate were above the standard limits for safe feed. This may adversely influence digestibility and utilization. It is better to detoxified and supplemented with good quality protein sources before feeding to animals. Key words: Sesame, capsule, proximate, amino acid, phytochemicals.

Interactions between climate change and UV penetration in the biosphere are resulting in the exposure of plants to new combinations of UV radiation and drought. In theory, the impacts of combinations of UV and drought may be additive, synergistic or antagonistic. Lack of understanding of the impacts of combined treatments creates substantial uncertainties that hamper predictions of future ecological change. Here, we compiled information from 52 publications and analysed the relative impacts of UV and/or drought. Both UV and drought have substantial negative effects on biomass accumulation, plant height, photosynthesis, leaf area and stomatal conductance and transpiration, while increasing stress-associated symptoms such as MDA accumulation and reactive-oxygen-species content. Contents of proline, flavonoids, antioxidants and anthocyanins, associated with plant acclimation, are upregulated both under enhanced UV and drought. In plants exposed to both UV and drought, increases in plant defense responses are less-than-additive, and so are the damage and growth retardation. Less-than-additive effects were observed across field, glasshouse and growth-chamber studies, indicating similar physiological response mechanisms. Induction of a degree of cross-resistance seems the most likely interpretation of the observed less-than-additive responses. The data show that in future climates, the impacts of increases in drought exposure may be lessened by naturally high UV regimes.

Salt stress is one of the important abiotic factors responsible for inhibiting the growth and development of commercially important crops. The demand for salt-tolerant varieties is growing tremendously with increasing soil salinity. In the present study, the effect of salt stress on four commercially important potato cultivars [‘Kufri Chipsona-1’ (CS-1), ‘Kufri Chandramukhi’ (KCM), ‘Kufri Pukhraj’ (KP), and ‘Kufri Jyoti’ (KJ)] was examined to identify the salt-tolerant levels using in vitro screening. The nodes from microshoots of these cultivars were cultured for 40 days on MS1 medium (basal MS medium + 10 µM AgNO3) containing 0, 100, 200, and 300 mM NaCl. Compared to the control, the morpho-physiological traits varied significantly with maximum growth reduction in cultivar ‘KJ’ cultivar and minimum in ‘CS-1’. The cultivar ‘CS-1’ showed no sign of leaf senescence and remained green on all the salt concentrations, while the other three cultivars (‘KCM’, ‘KP’, and ‘KJ’) turned brown and did not tolerate higher (300 mM) NaCl concentration. Moreover, cultivar ‘CS-1’ was found to have high chlorophyll, carotenoid, proline, sugars, and soluble protein contents on a medium containing 300 mM NaCl compared to the other three cultivars. As part of the antioxidant defense system, the analysis of various enzymes (peroxidase, ascorbate peroxidase, catalase, and superoxide dismutase) also showed a significant increase in their activity with an increasing NaCl concentration in cultivar ‘CS-1’. The study concluded that cultivar ‘CS-1’ possessed a higher level of salt tolerance and could adapt to saline environment. We can further conclude that the accumulation of osmolytes and increased antioxidant enzyme activities have an important role in imparting salt tolerance to the plants. Therefore, the outcomes of the study can be utilized as a platform to develop screening strategies for the improvement of commercially important crops.

Longer photoperiod in form of continuous light (24-h photoperiod without dark interruption) can alter the various physiological and biochemical processes of the plant. This study aimed to evaluate the effects of continuous light on various biochemical parameters associated with the growth and development of Vigna radiata L. (mung bean). The findings showed that leaf size and chlorophyll content of seedlings grown under continuous light were significantly greater than control plants subjected to 12 h light/12 h dark (12/12 h). The activity of antioxidant enzymes superoxide dismutase (SOD, 30.81%), catalase (CAT, 16.86%), guaiacol peroxidase (GPOD, 12.27%), malondialdehyde, (MDA, 39.31) and proline (14.81%) were notably higher in 24/0 h light period than 12/12 h light period grown seedling at an early stage (on Day 6) while they were constant at the later stage of development. Increased activity of amylase and invertase reveals higher assimilation and consumption of photosynthetic products. This study revealed that plants were stressed at first. However, they gradually became acclimated to continuous light and efficiently used the excess light in carbon assimilation.

Hydrogen sulfide closed Arabidopsis thaliana stomata by increasing the transcription of melatonin-producing enzymes and the post-translational modification levels to combat osmotic stress. Hydrogen sulfide (H2S) and melatonin (MEL) reportedly have similar functions in many aspects of plant growth, development and stress response. They regulate stomatal movement and enhance drought resistance. However, their physiological relationship is not well understood. Here, their crosstalk involved in osmotic stress resistance in Arabidopsis thaliana was studied. Exogenous H2S and MEL closed stomata under normal or osmotic stress conditions and increased the relative water contents of plants under osmotic stress conditions. At the same time, exogenous H2S and MEL responded to osmotic stress by increasing the content of proline and soluble sugar, and reducing malondialdehyde (MDA) content and relative conductivity. Using mutants in the MEL-associated production of serotonin N-acetyltransferase (snat), caffeic acid O-methyltransferase (comt1) and N-acetylserotonin methyltransferase (asmt), we determined that H2S was partially dependent on MEL to close stomata. Additionally, the overexpression of ASMT promoted stomatal closure. Exogenous H2S increased the transcription levels of SNAT, ASMT and COMT1. Furthermore, exogenous H2S treatments increased the endogenous MEL content significantly. At the post-translational level, H2S sulfhydrated the SNAT and ASMT, but not COMT1, enzymes associated with MEL production. Thus, H2S appeared to promote stomatal closure in response to osmotic stress by increasing the transcription levels of MEL synthesis-related genes and the sulfhydryl modification of the encoded enzymes. These results increased our understanding of H2S and MEL functions and interactions under osmotic stress conditions.

Abiotic stresses have a detrimental impact on plant growth and productivity and are a major threat to sustainable crop production in rapidly changing environments. Proline, an important amino acid, plays an important role in maintaining the metabolism and growth of plants under abiotic stress conditions. Many insights indicate a positive relationship between proline accumulation and tolerance of plants to various abiotic stresses. Because of its metal chelator properties, it acts as a molecular chaperone, an antioxidative defence molecule that scavenges reactive oxygen species (ROS), as well as having signalling behaviour to activate specific gene functions that are crucial for plant recovery from stresses. It also acts as an osmoprotectant, a potential source to acquire nitrogen as well as carbon, and plays a significant role in the flowering and development of plants. Overproduction of proline in plant cells contributes to maintaining cellular homeostasis, water uptake, osmotic adjustment and redox balance to restore the cell structures and mitigate oxidative damage. Many reports reveal that transgenic plants, particularly those overexpressing genes tailored for proline accumulation, exhibit better adaptation to abiotic stresses. Therefore, this review aims to provide a comprehensive update on proline biosynthesis and accumulation in plants and its putative regulatory roles in mediating plant defence against abiotic stresses. Additionally, the current and future directions in research concerning manipulation of proline to induce gene functions that appear promising in genetics and genomics approaches to improve plant adaptive responses under changing climate conditions are also highlighted.

Abiotic stresses, such as iron deficiency and high salinity, affect apple growth and development. WRKY transcription factors (TFs) are widely involved in the responses of plants to adverse stresses. In the present study, a new WRKY gene was isolated from Malus xiaojinensis and designated as MxWRKY53. Subcellular localization showed that MxWRKY53 was localized to the nucleus. The expression level of MxWRKY53 was highly affected by salt, low Fe, and high Fe stresses in M. xiaojinensis seedlings. When MxWRKY53 was introduced into Arabidopsis thaliana, it greatly enhanced the salt and Fe tolerance. When dealt with high and low Fe stresses, the overexpression of MxWRKY53 in transgenic A. thaliana resulted in higher levels of root length, fresh weight, and contents of chlorophyll and Fe than wild type (WT). Increased expression of MxWRKY53 in transformed A. thaliana also contributed to higher contents of chlorophyll and proline, and higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), while malondialdehyde (MDA) content was lower, especially in response to salt stress. Therefore, these results show that MxWRKY53 plays a positive role in the process of plant resistance to salt, low Fe, and high Fe stresses.

Cowpea (Vigna unguiculata (L.) Walp.) is an important commodity in West Africa. Its seeds are a valuable source of protein, vitamins, and income for humans. However, cowpea cultivation in Benin faces climatic constraints such as water stress caused by a prolonged absence of rain during the rainy season. Thus, this work aims at selecting cowpea varieties that can be cultivated in times of drought without compromising their yields and yield components. Twenty cowpea varieties were used, including 17 improved cultivars and 3 landraces. The experiment was conducted at the International Institute of Tropical Agriculture in Benin and laid at a split-plot design with four replicates. Each genotype was exposed to three water treatments: fully irrigated control, vegetative stress (when plants were 23 days old, drought stress was imposed for 30 days), and reproductive stress (once the first flowers were observed, water stress was imposed for 30 days). The results showed that photochemical yield, chlorophyll content, and relative water content were reduced under water deficit at the vegetative and reproductive stages. But there were no significant differences in proline content among cowpea varieties. Agronomic traits such as number of days to flowering, number of pods, yield per plant, the weight of 100 seeds, and harvest time showed significant differences under water stress. Overall, the landraces and cultivars including Kpodjiguegue, KVX 61-1, and IT 06-K-242-3 were the most tolerant to drought stress at the vegetative and reproductive stages and could potentially be used in breeding programs to improve drought tolerance of cowpeas.

Melatonin (MEL) is a ubiquitous molecule with pleiotropic roles in plant adaption to stress. In this study, we investigated the effects of foliar spray of 100 and 200 μM MEL on the biochemical and physiological traits linked with the growth performance of olive seedlings exposed to moderate (45 mM NaCl) and severe (90 mM NaCl) salinity. Both salt stress conditions caused a considerable reduction in leaf relative water content and the contents of photosynthetic pigments (carotenoids, chlorophylls a and b and total chlorophylls), K+ and Ca+2 , while the contents of Na+ and the activities of antioxidant enzymes increased. In addition, salt-stressed olive seedlings showed high accumulations of hydrogen peroxide (H2 O2 ), malondialdehyde (MDA) and electrolyte leakage (EL), indicating that olive seedlings suffered from salinity-induced oxidative damage. In contrast, MEL application revived the growth of olive seedlings, including shoot height, root length and biomass under salt stress conditions. MEL protected the photosynthetic pigments and decreased the Na+ /K+ ratio under both moderate and severe salt stresses. Furthermore, MEL induced the accumulations of proline, total soluble sugars, glycine betaine, abscisic acid and indole acetic acid in salt-stressed olive seedlings, which showed a positive correlation with improved leaf water status and biomass. MEL application also increased the activities of catalase, superoxide dismutase, ascorbate peroxidase and peroxidase in salt-stressed seedlings, resulting in lower levels of H2 O2 , MDA and EL in these plants. Taken together, MEL mitigates salinity through its roles in various biochemical and physiological processes, thereby representing a promising agent for application in crop protection. This article is protected by copyright. All rights reserved.

Boron (B) deficiency influences sugar beet development and productivity. A hydroponic set up of experiment was conducted by utilizing different B concentrations to study the impact of different morphological and physiological responses of sugar beet seedlings under B deficiency. The results showed that B deficiency (14 days of stress) inhibited the growth of different plant parts of sugar beet. The B deficiency significantly increased the leaf specific weight (SLW) and the root-shoot ratio of sugar beet seedlings. The activities of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) showed a decreasing tendency under B deficiency, while the contents of hydrogen peroxide (H2O2) and superoxide (O2−) increased with B concentration. Malonaldehyde (MDA) and proline contents were induced at B deficiency. In conclusion, B deficiency significantly reduced dry weight and leaf area, resulting in stunted sugar beet seedlings. It was manifested by a significant decrease in antioxidant enzyme activities and accumulation of ROS in the plant cells, inducing oxidative stress. The current study revealed that B deficiency affects plant growth and various morpho-physiological processes.

Drought stress is the main factor limiting the growth and crop yield in most regions; thus, reducing the effects of drought stress is a research priority worldwide. The aim of this experiment was to evaluate the effect of sodium nitroprusside (SNP) on physiological traits and grain yield of oilseed rape under drought stress. Two field experiments with three irrigation levels (I1: full irrigation (control), I2: irrigation cut-off at the beginning of pod development, and I3: irrigation cut-off at the beginning of grain filling) and SNP foliar applications with four levels (0, 100, 200 and 300 μM) were conducted during the 2015–2017 growing seasons. The results indicated that applying 200 and 300 μM of SNP significantly increased antioxidant enzymes, total chlorophyll, and proline at all levels of drought stress in comparison with applying zero and 100 μM of SNP. Moreover, applying SNP increased grain yield via improving the biochemical traits of the plant under stress and non-stress conditions. Comparison results of the average test of two years showed that the application of 200 and 300 μM SNP increased grain yield to 11.2 and 15.1% in control conditions, 33.6 and 36.7% in I2 and 20.9 and 40.6% in I1 compared to the control. Generally, the results indicated that applying SNP reduced the effects of water-deficit stress on oilseed rape.

Finger millet (Eleusine coracana L.) is an important nutri-cereal crop which is sensitive to salinity and vulnerable to blast disease caused by Magnaporthe grisea. The present study was therefore aimed to explore the potential of seed biopriming with four salinity tolerant Trichoderma isolates (TRU-21, TRU-14, TRU-33 and TRU-176) on the planting value parameters, physiological and biochemical responses in finger millet grown at various salt stress levels (0, 4, 6 and 8 dSm−1) and to examine their bio-efficacy towards M. grisea. The potential of the Trichoderma isolates in inhibiting M. grisea was assessed by recording the incidence of leaf blast disease using 0–5 SES scale. The Trichoderma treatments were found effective in enhancement of germination percentage and minimizing reduction percent germination. Seedlings raised from Trichoderma treated seeds exhibited significant enhancement on plant biomass, total chlorophyll content and chlorophyll fluorescence in comparison to untreated plants at all salt stress levels. Trichoderma treatments showed lower accumulation of malondialdehyde and H2O2 content revealing lower oxidative damage whereas total phenolics, proline content and superoxide dismutase content were higher in plants previously treated with Trichoderma. Current study reported resistant to moderately resistant response towards leaf blast disease in Trichoderma treated plants whereas susceptible response in untreated plants. Use of Trichoderma isolates thus, has been found to provide a sustainable approach to alleviate salt stress and leaf blast disease in finger millet by modulating growth attributes, physiological and biochemical responses, with TRU-14 (Trichoderma asperellum, ITCC-7903) showing most consistent effect for most of the traits studied.

Drought and heavy metal contaminated soil has become one of the main factors affecting the sustainable development of agricultural production and the ecological environment. Tartary buckwheat is rich in flavonoids and has a high tolerance to barren land and harsh environments. Chalcone synthase (CHS) is the key enzyme in the flavonoid biosynthesis pathway, and its gene expression is regulated by tissue development and abiotic stress. In this experiment, a tartary buckwheat variety named Xiqiao 2 was used as the experimental material to analyze the physiological characteristics of seedlings and to clone the CHS gene and analyze the expression in tartary buckwheat leaves under drought and cadmium (Cd) stress. The results showed that drought and Cd stress significantly reduced root vigor but increased the activity of peroxidase (POD) and superoxide dismutase (SOD) and the content of malondialdehyde (MDA), soluble sugar, soluble protein and proline in buckwheat seedlings. A 1188 bp FtCHS gene encoding 391 amino acid residues was cloned. The expression of the FtCHS gene in tartary buckwheat increased rapidly under Cd stress, reaching a maximum at 3 h that was approximately 20 times that of the control group (0 h). The expression of the FtCHS gene decreased rapidly under drought stress; the expression level was very low within 12 h, and the change was not significant, while the increase was obvious at 12–48 h. This result indicated that the FtCHS gene actively responded to Cd stress in a short amount of time and had relatively stable adaptability to drought stress. This study provides a theoretical basis for further research on the functional characteristics of the FtCHS gene and its molecular mechanism in tartary buckwheat under abiotic stresses such as drought and soil heavy metal pollution.

BACKGROUND Ice plant is a halophyte, known for its antioxidant activity and for being a highly functional food. It is capable of increasing its contents of health-promoting compounds when subjected to certain stresses such as salinity. The objective of this work was to determine the plant's best growing conditions to achieve both an optimal production of bioactive metabolites and high crop yield. Mesembryanthemum crystallinum were grown under semi-controlled conditions and four saline treatments were applied at: 0, 100, 200 and 300 mmol L-1 sodium chloride (NaCl), respectively. RESULTS The 100 mmol L-1 NaCl treatment induced a slight increase in shoot dry weight (DW) and enhanced the leaf area. At higher salinity levels, however, the shoot biomass decreased. The concentration of starch and total proteins declined as the concentration of salt increased, while the total soluble sugars (TSS) content was lower in 100 and 300 mmol L-1 NaCl treatments. Proline increased in conditions over 100 mmol L-1 NaCl. Furthermore, plants grown with 300 mmol L-1 of NaCl presented the highest values of glutathione, ascorbic acid and vitamin C. Antioxidant enzymes activity and total phenolics increased with the severity of the salinity. CONCLUSION Ice plant accumulates high levels of health-promoting compounds when grown with 300 mmol L-1 NaCl. A high concentration of beneficial compounds, however, is detrimental to the plant's growth. Moreover, 100 mmol L-1 NaCl treatment not only improved the concentration of bioactive and antioxidant compounds but also preserved the crop yield. It could thus be interesting to promote the cultivation of this high nutritional value plant in environments of moderate salinity. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Drought stress is one of the major constraints for soybean growth and productivity worldwide. The study was aimed to investigate drought-induced physiological and proteomic changes in soybeans, as well as drought relief using exogenous hydrogen peroxide (H2O2). In drought-stressed plants, H2O2 spray on the leaf surface improved relative water content (RWC), net photosynthetic rate (Pn), and stomatal conductance (Gs). Furthermore, exogenous H2O2 reduced drought stress-induced endogenous MDA and H2O2 levels, as well as increased the key antioxidant enzymes (SOD,CAT, APX and POD) activity and proline content in H2O2-treated soybean plants. These findings showed that H2O2 treatment significantly reduced drought stress by increasing the antioxidative defense system and osmotic adjustment. Furthermore, using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, a total of 27 differently expressed proteins was identified, wherein 23 were up-regulated and 4 were down-regulated under drought condition. These proteins were found to be involved in photosynthesis, energy and metabolism, plant defense and antioxidant, signaling and transport, and transcription regulation in response to H2O2 treatment in soybean under drought stress, according to in silico interactome analysis. These findings add to our understanding of H2O2-mediated drought stress alleviation, as well as the physiological and molecular responses of soybean to drought stress.

The study was carried out to evaluate the influence of application of Trichoderma viride and Bacillus subtilis on antioxidant enzymes, proline and lipid peroxidation to decrease the impact of salinity stress on chickpea (Cicer arietinum L.), a salinity sensitive crop. A pot experiment was conducted with contrasting set of genotypes (tolerant vs. sensitive) under salinity stress compared to control soil conditions in completely randomized design with three replications. Microbial inoculation was done through seed priming and application to soil at 20 days after sowing (DAS). Content of antioxidant enzymes, proline, and lipid peroxidation were assessed in leaves at flowering stage. Results showed that antioxidant enzymes viz., catalase, peroxidase, and superoxide dismutase were significantly increased under salinity stress compared to control condition and they were further increased with application of microbes either as seed priming alone or in combination with soil application at 20 DAS in both the genotypes under saline as well as control conditions. The content of lipid peroxidation increased significantly under salinity stress, and it was stronger pronounced in sensitive genotype while the lipid peroxidation content was decreased by application of microbes. Proline content increased under salinity stress, and it was further enhanced by the microbial inoculation. The study thus conclusively proved that Bacillus subtilis and Trichoderma viride positively increased content of antioxidant enzymes, proline, and lipid peroxidation in leaves of chickpea grown under salinity stress conditions. The best microbe species was Trichoderma viride as seed priming plus soil application. This can be an important additional approach to decrease the impact of salinity stress on chickpea crop.

A filed experiment was conducted to consider the impacts of bio-fertilizers (Azotobacter chroococcum and Glomus mosseae) and two levels of chemical fertilization ( 50% and 100% of recommended dose) on proline content and activities of antioxidant enzymes (catalase and peroxidase) in wheat Triticum aestivum L. cultivar IPA 99 under drought conditions (50% and 20% of soil field capacity). Bio-fertilization involved treatment with A. chroococcum (Azoto) and G. mosseae (AMF), singly or in combination. The experiment was conducted by applying a Randomized Complete Block Design (RCBD) with three replications. The results of this study showed that the treatment utilizing Azoto+AMF fertilizer with concentrated chemical fertilizer (100%) significantly decreased proline content and the activities of antioxidant enzymes under drought conditions. In addition, the percentage of mycorrihzal root infection was increased. The lowest values of proline content and catalase and peroxidase activities (3.35 µmole/g, 84.52 unit/ml, 90.90 unit/ml, respectively) were achieved by the application of combined bio-fertilizers with 100% of chemical fertilizer and 50% water deficit. The combined bio-fertilizer application with 50% of chemical fertilizer and 20% water deficit achieved the maximum mycorrihzal infection percentage (90%).

BACKGROUND β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP) is a physiological indicator in response to drying soil. However, how abscisic acid (ABA) modulates β-ODAP accumulation and its related agronomic characteristics in drought stressed grass pea (Lathyrus sativus L.) continue to be unclear. The present study aimed to evaluate the effects of ABA addition on drought tolerance, agronomic characteristics and β-ODAP content in grass pea under drought stress. RESULTS Exogenous ABA significantly promoted ABA levels by 19.3% and 18.3% under moderate and severe drought stress, respectively, compared to CK (without ABA, used as control check treatment). ABA addition activated earlier trigger of non-hydraulic root-sourced signal at 69.1% field capacity (FC) (65.5% FC in CK) and accordingly prolonged its operation period to 45.6% FC (49.0% FC in CK). This phenomenon was mechanically associated with the physiological mediation of ABA, where its addition significantly promoted the activities of leaf superoxide dismutase, catalase and peroxidase enzymes and the biosynthesis of leaf proline, simultaneously lowering the accumulation of malondialdehyde and hydrogen peroxide under moderate and severe stresses. Interestingly, ABA application significantly increased seed β-ODAP content by 21.7% and 21.3% under moderate and severe drought stress, but did not change leaf β-ODAP content. Furthermore, ABA application produced similar shoot biomass and grain yield as control groups. CONCLUSION Exogenous ABA improved the drought adaptability of grass pea and promoted the synthesis of β-ODAP in seeds but not in leaves. Our findings provide novel insights into the agronomic role of ABA in relation to β-ODAP enrichment in grass pea subjected to drought stress. © 2021 Society of Chemical Industry.

Drought is believed to be one of the most important abiotic stresses, which drastically affects wheat production worldwide. Jasmonates, as plant growth regulators, could modify the effects of environmental stresses. Therefore, we conducted the present study to investigate the physiological responses of wheat cultivars to exogenous methyl jasmonate (MeJA) under drought stress during two crop years of 2015–2017. The results revealed that the irrigation cut-off regime at the booting decreased Fv/Fm, RWC, peroxidase activity, and grain yield; whereas it increased proline, malondialdehyde content, protein, and electrolyte leakage. The drought-tolerant cultivar, Sirvan had 13.7% higher grain yield than Pishtaz cultivar in drought stress owing to higher Fv/Fm, proline, RWC, peroxidase activity, and lower electrolyte leakage and MDA. Spraying 50 μM of MeJA increased chlorophyll and carotenoids (8.7% and 6.93%), proline (26.8%), and peroxidase activity (31.4%); whereas 100 μM of MeJA increased the RWC (2.5%), Fv/Fm (9.3%) and decreased membrane electrolyte leakage (6.7%) compared to hormone-free conditions. According to the results drought stress decreased certain physiological traits, the foliar application with 100 μM of MeJA could increase the grain yield (9.2% in irrigation cut-off at booting and 6.8% at the milk stage) and then partially compensate for the reduction caused by drought stress. Therefore, for minimizing the effect of drought stress, we could recommend the use of MeJA and drought-tolerant cultivar.

Rising temperatures, globally and locally, would be detrimental for cool- and summer-season food legumes, such as lentil (Lens culinaris Medik.). Lentil is highly sensitive to supra-optimal temperatures (> 30 °C), particularly during reproductive growth, resulting in flower and pod losses. Thus, suitable strategies are needed to introduce heat tolerance in this legume. Here, we evaluated the efficacy of nitric oxide (NO)—applied as foliar treatment of 1 mM sodium nitroprusside (SNP), twice (one day before final exposure to high temperature, and again five days later)—on heat-stressed (32/20 °C) lentil genotypes, differing in heat sensitivity. As a result of heat stress, endogenous NO increased significantly in heat-tolerant genotypes (46–62% in leaves and 66–68% in anthers, relative to the respective controls), while it decreased in heat-sensitive (HS) genotypes (27–30% in leaves and 28–33% in anthers, relative to the respective controls). Foliar supplementation with SNP markedly increased endogenous NO in leaves and anthers of both the control and heat-treated plants. Heat stress significantly accelerated phenology, damaged membranes, chlorophyll, chlorophyll fluorescence, cellular viability, and decreased leaf water status, carbon fixing and assimilating ability, less so in plants treated with SNP. Heat stress plus SNP significantly improved carbon fixation (as RuBisCo activity) and assimilation ability, (as sucrose concentration (in leaves and anthers), sucrose synthase and vacuolar acid invertase activity, reducing sugars), as well as osmolyte accumulation (proline and glycine betaine) in leaves and anthers. Moreover, SNP-treated plants had significantly less oxidative damage—measured as malondialdehyde and hydrogen peroxide concentrations—in leaves and anthers, relative to the respective control. Reproductive function—assessed as pollen grain germination and viability, stigma receptivity, and ovular viability—decreased markedly in plants exposed to heat stress alone, more so in HS genotypes, but increased significantly with SNP treatment as a consequence of improved leaf and anther function, to significantly increase the pod and seed numbers in heat-stressed lentil plants, relative to heat-stress alone.

The effect of an elevated concentration of СО2 (800 ppm) on the growth rate, efficiency of photosystem I (PS I) and photosystem II (PS II), content of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPc), as well as proline and sodium and potassium ions, was investigated in the shoots of С4-halophyte Kochia prostrata (L.) Schrad. An elevated concentration of СО2 caused a decrease in accumulation of dry biomass (1.2 times), a rise in the content of proline (1.2 times) and potassium ions (1.3 times), and a shortening of time required to reach the maximum P700 oxidation level (PS I) (1.7 times). The content of sodium ions and water in the shoots and efficiency of PS II (Fv/Fm) did not change. Immunoblotting showed that, at the elevated concentration of СО2, the ratio between Rubisco and PEPc proteins rose from 1.3 to 3.4. The shortening of time required to reach the maximum oxidation level of PS I indirectly points to a reduction in the activity of cyclic transport of electrons responsible for efficient operation of the С4-carbon-concentrating mechanism. The high concentration of СО2 is suggested to activate the С3-pathway of photosynthesis in С4-halophyte K. prostrata.

Background Welsh onion constitutes an important crop due to its benefits in traditional medicine. Nitrogen is an important nutrient for plant growth and yield; however, little is known about its influence on the mechanisms of Welsh onion regulation genes. In this study, we introduced a gene expression and amino acid analysis of Welsh onion treated with different concentrations of nitrogen (N0, N1, and N2 at 0 kg/ha, 130 kg/ha, and 260 kg/ha, respectively). Results Approximately 1,665 genes were differentially regulated with different concentrations of nitrogen. Gene ontology enrichment analysis revealed that the genes involved in metabolic processes, protein biosynthesis, and transportation of amino acids were highly represented. KEGG analysis indicated that the pathways were related to amino acid metabolism, cysteine, beta-alanine, arginine, proline, and glutathione. Differential gene expression in response to varying nitrogen concentrations resulted in different amino acid content. A close relationship between gene expression and the content of amino acids was observed. Conclusions This work examined the effects of nitrogen on gene expression and amino acid synthesis and provides important evidence on the efficient use of nitrogen in Welsh onion.

The mechanism of melatonin (MT) induced chilling tolerance in harvested cucumber fruit was investigated at commercial maturity. In this study, cucumber fruits were treated with 100 µmol L–1 MT at 4°C and 90% relative humidity for 15 d of storage. In comparison with the control, cucumber treatment with MT resulted in reduced chilling injury (CI), decreased electrolyte leakage and enhanced firmness. The fruits treated with MT showed higher chlorophyll contents in storage conditions with suppressed chlorophyllase enzyme activity. MT treatment increased arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) enzyme activities. Moreover, enhanced expression of the Cucumis sativus ADC (CsADC) and C. sativus ODC (CsODC) genes resulted in the accumulation of polyamine contents. Similarly, proline levels exhibited higher levels among treated fruits. Meanwhile, the proline synthesizing enzymes △1-pyrroline-5-carboxylate syntheses (P5CS) and ornithine aminotransferase (OAT) were significantly increased, while a catabolic enzyme of proline dehydrogenase (PDH) activity was inhibited by treatment. In addition, MT induced expression of C. sativus OAT (CsOAT) and C. sativus P5CS (CsP5CS) genes. Cucumber fruits treated with MT also exhibited higher γ-aminobutyric acid (GABA) content by enhanced GABA transaminase (GABA-T) and glutamate decarboxylase (GAD) enzyme activities and a higher C. sativus GAD (CsGAD) gene expression. To sum up, the results show that MT treatment enhanced chilling tolerance, which was associated with the regulation of polyamines, as well as proline and γ-aminobutyric acid.

Drought-induced water stress affects the productivity of the Vanilla planifolia Jacks. ex Andrews crop. In vitro culture technique is an effective tool for the study of water stress tolerance mechanisms. This study aimed to evaluate the morphological, physiological and biochemical response of V. planifolia under in vitro water stress conditions induced with polyethylene glycol (PEG). In vitro regenerated shoots of 2 cm in length were subjected to different concentrations of PEG 6000 (0, 1, 2 and 3% w/v) using Murashige and Skoog semi-solid culture medium. At 60 days of culture, different growth variables, dry matter (DM) content, chlorophyll (Chl), soluble proteins (SP), proline (Pro), glycine betaine (GB), stomatal index (SI) and open stomata (%) were evaluated. Results showed a reduction in growth, Chl content, SP, SI and open stomata (%) with increasing PEG concentration, whereas DM, Pro and GB contents rose with increasing PEG concentration. In conclusion, PEG-induced osmotic stress allowed describing physiological and biochemical mechanisms of response to water stress. Furthermore, the determination of compatible Pro and GB osmolytes can be used as biochemical markers in future breeding programs for the early selection of water stress tolerant genotypes.

Superoxide dismutases (SODs) protect the cells by catalyzing the dismutation of harmful superoxide radicals (O2•-) into molecular oxygen (O2) and hydrogen peroxide (H2O2). Here, a Cu, Zn SOD (WT) from a high altitude plant (Potentilla atrosanguinea) was engineered by substituting a conserved residue proline to glycine at position 61 (P61G). The computational analysis showed higher structural flexibility and clusters in P61G than WT. The P61G exhibited moderately higher catalytic efficiency (Km = 0.029 μM, Vmax = 1488) than WT protein (Km = 0.038 μM, Vmax = 1290.11). P61G showed higher thermostability as revealed from residual activity (72.25% for P61G than 59.31% for WT after heating at 80 °C for 60 min), differential calorimetry scanning and CD-spectroscopic analysis. Interestingly, the P61G mutation also resulted in enhanced tolerance to H2O2 inactivation than WT protein. The finding on enhancing the biophysico-chemical properties by mutating conserved residue could stand as an example to engineer other enzymes. Also, the reported mutant can be exploited in food and pharmaceutical industries.

Glycine betaine is an osmoprotectant compound which enhances cell tolerance in plant species in response to environmental stresses. This study aimed to investigate the effect of exogenous application of glycine betaine on some antioxidant activities of tobacco plants overexpressing P5CS gene. Sterile tobacco seedlings with four to six leaves were transferred to MS medium containing 0, 100, and 200 mM NaCl, after which glycine betaine (20 and 40 mg l-1) were foliar sprayed on the surface of the plants. After four weeks, glycine betaine treatment enhanced the antioxidant capacity of the plant through activation of catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX). In contrast, H2O2 content and MDA level were reduced by glycine betaine under similar conditions. Therefore, application of exogenous glycine betaine under salt stress improved stress tolerance in T and non-T plants. Meanwhile, our results indicated the positive effect of glycine betaine in T plants was greater than in non-T plants. On the other hand, this result suggested that the synergistic effects of glycine betaine and proline in plants enhanced the antioxidant defense system in T plants overexpressing P5CS gene.

Proline accumulation is one of the most common reactions in plants under drought stress. Pyrroline-5-carboxylate reductase (P5CR) is the final enzyme and plays an important role in proline biosynthesis. The Chinese wild grapevine Vitis yeshanensis J.X. Chen accession 'Yanshan-1' is highly resistant to drought, but the genetic and molecular mechanisms associated with this resistance have not been elucidated. Here, we cloned a VyP5CR gene (Genbank ID: MZ226960) from 'Yanshan-1', and evaluated its transcriptional response to drought, NaCl, cold, as well as exogenous ABA, MeJA and SA. Tissue specific analysis showed that VyP5CR could be expressed in various organs and was highly expressed in roots. To gain insight into the roles of VyP5CR, we overexpressed VyP5CR in Arabidopsis thaliana (Arabidopsis). Transgenic Arabidopsis plants expressing VyP5CR showed enhanced survival rate, smaller stomata in response to severe drought, as well as stronger root growth on a medium containing mannitol. Under drought stress, VyP5CR-OE plants showed reduced levels of MDA, H2O2 and O2-, and higher proline content, SOD and POD activity. In addition, VyP5CR-OE plants showed increased induction of the drought-related genes COR15A, COR47, DREB2A, KIN1, NCED3 and RD29A. Taken together, these experiments reveal that VyP5CR can promote the drought tolerance of transgenic Arabidopsis. Besides, an interacting protein with VyP5CR, VyCSN5B (COP9 signalosome complex subunit 5b), was screened out by yeast two-hybrid and verified by bimolecular fluorescence complementation assay.