Salt-tolerant Genotypes Research Articles

Screening of Salt-Tolerant Rice Landraces by Seedling Stage Phenotyping and Dissecting Biochemical Determinants of Tolerance Mechanism

Genetic diversity is a useful resource for crop improvement. In this study, a total of 28 rice genotypes were screened to isolate potential salt-tolerant genotypes at the seedling stage using hydroponic system. Different morpho-physiological indicators were used to classify tolerant and susceptible genotypes and biochemical determinants were dissected to clarify the underlying tolerance mechanism. Rice seedling were treated with two salinity levels (EC-1.1 dSm‒1 (control) and EC-7 dSm‒1) for 18 days. Salt stress resulted in significant decrease of growth and physiological traits in all genotypes; however, the lowest reduction was observed in some salt-tolerant genotypes namely Ghunsi, Nonabokra, Hogla, Holdegotal, Vusieri, and Kanchon. Cluster analysis considering percent reduction of growth parameters categorized the genotypes into four main sub-clusters and importantly, the salt-tolerant landraces were placed in the same cluster (cluster-II) with salt-tolerant check genotypes. The results of principle component analyses also demonstrated highly salt-tolerant genotypes were Vusieri > Nonabokra > Ghunsi > Hogla > Holdegotal > Kanchon. To explore the potential biochemical basis of salt stress tolerance, three tolerant genotypes were further characterized along with a salt-sensitive genotype. The higher K+/Na+ ratios noted for all salt-tolerant landraces thus indicating that the K+/Na+ ratio serves as a reliable indicator of salt tolerance in rice. The higher increment of proline content, catalase, ascorbate peroxidase activities, and comparatively lower accumulation of H2O2 and MDA were reported in salt-tolerant landraces as compared with salt-sensitive genotype. Therefore, these landraces could be utilized as promising genotypes as a source of salt-tolerant parents in the hybridization program for the development of high-yielding salt-tolerant rice variety as well as in isolating salt-tolerant genes.

Multidimensional Evaluation for Detecting Salt Tolerance of Bread Wheat Genotypes Under Actual Saline Field Growing Conditions.

Field-based trials and genotype evaluation until yielding stage are two important steps in improving the salt tolerance of crop genotypes and identifying what parameters can be strong candidates for the better understanding of salt tolerance mechanisms in different genotypes. In this study, the salt tolerance of 18 bread wheat genotypes was evaluated under natural saline field conditions and at three saline irrigation levels (5.25, 8.35, and 11.12 dS m−1) extracted from wells. Multidimensional evaluation for salt tolerance of these genotypes was done using a set of agronomic and physio-biochemical attributes. Based on yield index under three salinity levels, the genotypes were classified into four groups ranging from salt-tolerant to salt-sensitive genotypes. The salt-tolerant genotypes exhibited values of total chlorophyll, gas exchange (net photosynthetic rate, transpiration rate, and stomatal conductance), water relation (relative water content and membrane stability index), nonenzymatic osmolytes (soluble sugar, free proline, and ascorbic acid), antioxidant enzyme activities (superoxide dismutase, catalase, and peroxidase), K+ content, and K+/Na+ ratio that were greater than those of salt-sensitive genotypes. Additionally, the salt-tolerant genotypes consistently exhibited good control of Na+ and Cl− levels and maintained lower contents of malondialdehyde and electrolyte leakage under high salinity level, compared with the salt-sensitive genotypes. Several physio-biochemical parameters showed highly positive associations with grain yield and its components, whereas negative association was observed in other parameters. Accordingly, these physio-biochemical parameters can be used as individual or complementary screening criteria for evaluating salt tolerance and improvement of bread wheat genotypes under natural saline field conditions.

Salt tolerance involved candidate genes in rice: an integrative meta-analysis approach

BackgroundSalinity, as one of the main abiotic stresses, critically threatens growth and fertility of main food crops including rice in the world. To get insight into the molecular mechanisms by which tolerant genotypes responds to the salinity stress, we propose an integrative meta-analysis approach to find the key genes involved in salinity tolerance. Herein, a genome-wide meta-analysis, using microarray and RNA-seq data was conducted which resulted in the identification of differentially expressed genes (DEGs) under salinity stress at tolerant rice genotypes. DEGs were then confirmed by meta-QTL analysis and literature review.ResultsA total of 3449 DEGs were detected in 46 meta-QTL positions, among which 1286, 86, 1729 and 348 DEGs were observed in root, shoot, seedling, and leaves tissues, respectively. Moreover, functional annotation of DEGs located in the meta-QTLs suggested some involved biological processes (e.g., ion transport, regulation of transcription, cell wall organization and modification as well as response to stress) and molecular function terms (e.g., transporter activity, transcription factor activity and oxidoreductase activity). Remarkably, 23 potential candidate genes were detected in Saltol and hotspot-regions overlying original QTLs for both yield components and ion homeostasis traits; among which, there were many unreported salinity-responsive genes. Some promising candidate genes were detected such as pectinesterase, peroxidase, transcription regulator, high-affinity potassium transporter, cell wall organization, protein serine/threonine phosphatase, and CBS domain cotaining protein.ConclusionsThe obtained results indicated that, the salt tolerant genotypes use qualified mechanisms particularly in sensing and signalling of the salt stress, regulation of transcription, ionic homeostasis, and Reactive Oxygen Species (ROS) scavenging in response to the salt stress.

English

Increased production of sugar beet under rainfed conditions on saline–sodic soils in the Iranian areas highlights the importance of salt tolerant varieties. Screening of genotypes for salinity tolerance is difficult in field due to heterogeneity of physical and chemical properties of soil. In order to evaluate the salinity tolerance of 21 sugar beet monogerm O-types lines, a pot experiment was conducted using a split plot design. The evaluation of plants was performed using 11 morphological and physiological traits at vegetative growth stage under severe salt stress (∼16 dS m-1) and control (0.3 dS m-1) for 8 weeks. Salinity stress significantly reduced weight related traits. The response of genotypes for total weights and stem weights was very similar under both conditions. But, ranking of O-type lines for root weights under normal and stress condition was different. Indeed, there was high significant genotype × treat interaction for two these traits. Cluster analysis by using STI index of all traits allowed the identification of tolerant, moderate tolerant and sensitive genotypes toward salinity. The four salt-tolerant genotypes, O-type 9669, O-type 1609, O-type 463-2, and O-type 463-5 identified in this study, could be used in the development of salt-tolerant sugar beet varieties. In the second part of this study in order to assess a simple, rapid, and nondestructive method to estimate chlorophyll content, the chlorophyll meter (SPAD 502) readings were recorded and the relation was determined. Regression analysis indicated that there was a significant linear regression between chlorophyll content and chlorophyll meter and about 74% of changes in chlorophyll meter based on chlorophyll content were predicted.   Key words: Sugar beet (beta vulgaris L.), salt tolerant index, screening, hybrid.

Growth-Stimulatory Effect of Quorum Sensing Signal Molecule N-Acyl-Homoserine Lactone-Producing Multi-Trait Aeromonas spp. on Wheat Genotypes Under Salt Stress.

Salinity is one of the major threats to agricultural productivity worldwide. Soil and plant management practices, along with inoculation with plant-beneficial bacteria, play a key role in the plant’s tolerance toward salinity stress. The present study demonstrates the potential of acyl homoserine lactone (AHL)-producing plant growth promoting rhizobacteria (PGPR) strains of Aeromonas sp., namely, SAL-17 (accession no. HG763857) and SAL-21 (accession no. HG763858), for growth promotion of two wheat genotypes inherently different for salt tolerance potential. AHLs are the bacterial signal molecules that regulate the expression of various genes in bacteria and plants. Both Aeromonas spp., along with innate plant-growth-promoting (PGP) and salt tolerance traits, showed AHL production which was identified on tandem mass spectrometry as C6-HSL, 3-OH-C5-HSL, 3-OH-C6-HSL, 3-oxo-C7-HSL C10-HSL, 3-oxo-C10-HSL, 3-OH-C10-HSL, 3-oxo-C12-HSL and C6-HSL, and 3-oxo-C10-HSL. The exogenous application of purified AHLs (mix) significantly improved various root parameters at 200 mM NaCl in both salt-sensitive (SSG) and salt-tolerant (STG) genotypes, where the highest increase (≈80%) was observed where a mixture of both strains of AHLs was used. Confocal microscopic observations and root overlay assay revealed a strong root colonization potential of the two strains under salt stress. The inoculation response of both STG and SSG genotypes was evaluated with two AHL-producing strains (SAL-17 and SAL-21) and compared to non-AHL-producing Aeromonas sp. SAL-12 (accession no. HG763856) in saline (EC = 7.63 ms/cm2) and non-saline soil. The data reveal that plants inoculated with the bacterial consortium (SAL-21 + SAL-17) showed a maximum increase in leaf proline content, nitrate reductase activity, chlorophyll a/b, stomatal conductance, transpiration rate, root length, shoot length, and grain weight over non-inoculated plants grown in saline soil. Both STG and SSG showed relative effectiveness toward inoculation (percent increase for STG: 165–16%; SSG: 283–14%) and showed a positive correlation of grain yield with proline and nitrate reductase activity. Furthermore, principal component analysis (PCA) and categorical PCA analysis clearly showed an inoculation response in both genotypes, revealing the effectiveness of AHL-producing Aeromonas spp. than the non-AHL-producing strain. The present study documents that the consortium of salt-tolerant AHL-producing Aeromonas spp. is equally effective for sustaining the growth of STG as well as SSG wheat genotypes in saline soil, but biosafety should be fully ensured before field release.

Comparative metabolomic profiling in the roots of salt-tolerant and salt-intolerant maize cultivars treated with NaCl stress

Maize crops are sensitive to NaCl stress, which is one of the most harmful abiotic stresses affecting agricultural productivity. To gain further insights into the differential metabolic responses to NaCl stress, we employed metabolomics and physiological approaches to understand the response of salt-tolerant (PH6WC) and sensitive (PH4CV) cultivars of maize. Salt stress caused a significant reduction in root growth, lower root numbers, softened roots, leaf etiolation, inhibition of leaf formation, and decreased shoot height and stem width in both the tolerant and sensitive genotypes compared with the control. These morphological characteristics increased with the progression of the NaCl concentration, however, they were less prominent in the salt-tolerant genotype. Evans blue staining demonstrated that NaCl-induced root cell death, and the root cells of 'PH4CV' were almost completely dead following 9 d of exposure to 100 mM NaCl. Under treatment with 100 mM NaCl, 79 compounds in the roots of 'PH4CV' were identified as being significant metabolites, and 85 compounds were identified as being significant metabolites in the roots of 'PH6WC'. The NaCl-induced changes in the metabolomes of these two maize cultivars indicate that 80 root-based compounds were different between NaCl-treated plants and controls. Among these metabolites, 30 were found in both maize cultivars when responding to NaCl stress. These compounds were associated with the metabolism of some basic compounds such as cis-9-palmitoleic acid, L-pyroglutamic acid, galactinol, deoxyadenosine, and adenine. The changing abundance of the 30 metabolites was not completely consistent in 'PH4CV' and 'PH6WC'. Glucose metabolism was exclusively induced by NaCl in the 'PH4CV' maize seedlings whereas nucleic acid metabolism was more significant in the 'PH6WC' maize seedlings in response to NaCl stress. Overall, 'PH6WC' and 'PH4CV' responded differently to NaCl stress, and this information is helpful in understanding how maize seedlings respond to this type of abiotic stress.

Proteome dynamics and transcriptome profiling in sorghum [Sorghum bicolor (L.) Moench] under salt stress.

Sorghum is a C4 cereal grain crop which is well adapted to harsh environment. It is a potential model for gaining better understanding of the molecular mechanism due to its wider adaptability to abiotic stresses. In this study, protein extraction was standardized using different methods to study the electrophoretic pattern of sorghum leaves under different salinity levels. The extraction of soluble protein with lysis buffer, followed by its clean-up was found to be the most effective method. The different profiles of salt-responsive proteins were analyzed in G-46 and CSV 44F sorghum genotypes based on their tolerance behavior towards salinity. The kafirin level also changed depending upon the concentration and exposure time to salts suggesting the stored proteins as energy source under stress conditions. The relative expression of salt-responsive genes was studied using Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) which might be used as a molecular screening tool for identification of salt-tolerant genotypes in affected areas. The validated responses were examined in terms of metabolic changes and the expression of stress-induced proteins-viz. heat shock proteins (hsp) via immunoblotting assay. The results showed that the two sorghum genotypes adopted distinct approaches in response to salinity, with G-46 performing better in terms of leaf function. Also, we have standardized different protein extraction methods followed by their clean-up for electrophoretic profiling.

Morphological and physiological traits reveal differential salinity tolerance of two contrasting Glandularia cultivars

In view of the current, continuous decrease of water availability, the need to explore new mitigation alternatives has given focus to salt-tolerant genotypes. The aim of this work was to study salt tolerance of two ornamental cultivars of Glandularia (Glandularia x hybrida) of contrasting vigor, Dulce Coral and Extrema Violeta, breeded at the Floriculture Institute of INTA. A greenhouse experiment was carried out with potted plants. Plants were subjected to four salt treatments 1.2, 2.4, 3.5, 4.4 dS m−1 (EC), and a control (0.03 dS m−1). Shoot dry weight of Dulce Coral was not affected by salinity. In contrast, the dry weight of Extrema Violeta decreased sharply as salinity increased. The root:shoot ratio was always higher for Extrema Violeta than Dulce Coral. The leaves of Dulce Coral accumulated less Na+ and Cl− than Extrema Violeta. Moreover, Extrema Violeta exhibited severe foliar salt damage, but Dulce Coral showed only a few, without compromising its commercial value. Besides, Dulce Coral had a higher assimilation rate than Extrema Violeta at all treatments. All these features could suggest Na+ and Cl− exclusion as salt-tolerant mechanism for Dulce Coral. Other mechanisms adopted by Dulce Coral to cope with salinity was the maintenance of a higher K+/Na+ and Ca2+/Na+ ratio in its leaves, a lower root:shoot ratio and the maintenance of photosynthesis. Therefore, Dulce Coral could be proposed as a parent for breeding programs with the objective of improving salt tolerance in Glandularia. In this exploratory study, we distinguish some of the most important physiological (K+/Na+ and Ca2+/Na+) and morphological (root:shoot ratio) traits related to salinity tolerance in Glandularia.

Metabolic contribution to salinity stress response in grains of two barley cultivars with contrasting salt tolerance

Soil salinity is a major abiotic stressor and a serious threat to global food security. Biochemical compounds synthesised by plants ameliorate the effects of such stressors in characteristic ways. It is crucial to unravel the key components of the salt tolerance network to engineer salt-tolerant genotypes of crops. For the elucidation of the metabolic contribution to salinity response (long-term stress under 100 mM NaCl) in selected cultivars, we used a gas chromatography mass spectrometry approach. The metabolic profiling of grains yielded sixty-five metabolites. By comparing a salt-sensitive cultivar of barley (Scope) to a salt-tolerant one (GrangeR), we identified six and twenty significant metabolites in salt-stressed seeds of Scope and GrangeR, respectively. These included amino acids, sugars, sugar derivatives and organic acids. Whilst the concentrations of fructose reduced, glycine, glucitol and urea accumulated under salt stress in both varieties. Amino acids such as phenylalanine, tryptophan and tyrosine, sugar acids such as galactaric acid and glucuronic acid, and several other key metabolites accumulated in GrangeR only. These metabolites are relevant to metabolic pathways of amino acid metabolism, energy metabolism, carbohydrate metabolism, glycolysis, gluconeogenesis, pyruvate metabolism, shikimate pathway, TCA cycle, inositol phosphate metabolism and galactose metabolism. Hence these compounds could be potentially used as biomarkers of abiotic stress responses and effects on grain quality and yield parameters. This work provides greater insights into functional metabolism in response to salinity stress and may help to dissect patterns associated with salt responses. Metabolites identified in this work could serve as accurate markers for salt-tolerant crop selection in breeding programs.

Evaluation of indigenous Omani alfalfa landraces for morphology and forage yield under different levels of salt stress.

Alfalfa is the major fodder crop of Sultanate Oman, but salinity is a major problem in its cultivation. Therefore, thirty-four alfalfa (Medicago sativa L.) landraces of Oman were evaluated for morphology and forage yield response to different salinity levels viz. 1 (control), 3, 6, 9, and 12 dS m-1 under greenhouse conditions. The experiment was conducted under a completely randomized design. Different alfalfa landraces responded differently to the five salinity levels for plant height, number of branches, number of leaves, leaflet width, leaflet length, forage fresh weight, and forage dry matter yield. Salt stress caused a reduction in growth and dry matter yield of alfalfa landraces with exception of some, which responded positively to the salinity levels of 3 and 6 dS m-1 compared to control for the number of leaves per plant. Moreover, some landraces had better forage fresh weight and dry matter yield at 6 dS m-1 than 3 dS m-1. Alfalfa landraces OMA 257, OMA, 245, OMA 270, OMA 315, OMA 211, OMA 117, OMA 56, OMA 239, OMA 148, OMA 131, OMA 95, OMA 263, OMA 262, OMA 289 and OMA 220 were designated as salt tolerant based on their overall performance across salinity levels of 6, 9 and 12 dS m-1. However, the landraces OMA 305, OMA 100, OMA 211, OMA 148, OMA 60, OMA 248, OMA 9, OMA 88, and OMA 302 collected were sensitive to 6, 9 and 12 dS m-1 salinity stress. The study showed the variation of alfalfa landraces potential for salinity tolerance, and their potential for cultivation in saline areas and/or use in breeding programs aimed to develop salt tolerant alfalfa genotypes.

Transcriptome Analysis Reveals Complex Defensive Mechanisms in Salt-Tolerant and Salt-Sensitive Shrub Willow Genotypes under Salinity Stress.

Salinity stress is one of the most devastating abiotic stresses limiting plant growth and productivity. As a moderately salt-tolerant crop, shrub willow (Salix spp.) is widely distributed over the world and can provide multiple bioenergy product and environmental benefits. To delve into the salt tolerance mechanism and screen out salt-tolerant genes, two shrub willow cultivars (a salt-sensitive genotype JW9-6 and a salt-tolerant genotype JW2372) at three time points (0, 2, and 12 h) after NaCl treatments were used for RNA sequencing. A comparative analysis between genotypes and time points showed 1,706 differentially expressed genes (DEGs), of which 1,029 and 431 DEGs were only found in the JW9-6 and JW2372, respectively. Gene Ontology (GO) and MapMan annotations suggested that many DEGs were involved in various defense-related biological pathways, including cell wall integrity, hormone signaling, antioxidant system, heat shock proteins, and transcription factors. Compared to JW9-6, JW2372 contained more DEGs involved in the maintenance of the cell wall integrity, ABA, and ethylene signal transduction pathways. In addition, more DEGs encoding heat shock proteins were found in JW2372. Instead, transcription factors including ERF, MYB, NAC, and WRKY were found to be more differentially expressed in JW9-6 under salinity stress. Furthermore, expressions of nine randomly selected DEGs were verified by qRT-PCR analysis. This study contributes in new perspicacity into underlying the salt tolerance mechanism of a shrub willow at the transcriptome level and also provides numerous salt-tolerant genes for further genetic engineering and breeding purposes in the future.

Physiological and antioxidant responses of cultivated and wild barley under salt stress

Saline soil is a critical environmental problem affecting crop yield worldwide. Tibetan wild barley is distinguished for its vast genetic diversity and high degree of tolerance to abiotic stress, including salinity. The present study compared the response of antioxidant defense system in the XZ16 wild and CM72 cultivated barleys to salt stress. Wild barley was relatively more tolerant than cultivated CM72, salt-tolerant cultivar, with less Na<sup>+</sup> uptake and more K<sup>+</sup>, Ca<sup>2+</sup>, and Mg<sup>2+</sup> retention in plant tissues. The results of diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining showed that XZ16 had significantly lower H<sub>2</sub>O<sub>2</sub> and O<sub>2</sub><sup>−</sup> concentrations than a salt-sensitive cultivar Gairdner, suggesting that the salt-tolerant genotype suffer from less oxidative damage. Moreover, XZ16 and Gairdner had the highest and lowest anti-oxidative enzyme activities and proline content in plant tissues. In addition, the microscopic examination revealed that DNA damage in cv. Gairdner was closely correlated to oxidative stress, representing that more reactive oxygen species accumulation in plants tissues leads to subsequent DNA damage. The present results show that higher salt tolerance of wild barley XZ16 is attributed to less Na<sup>+</sup> accumulation and stronger anti-oxidative capacity.

Expression level of Na+ homeostasis-related genes and salt-tolerant abilities in backcross introgression lines of rice crop under salt stress at reproductive stage.

Salt stress in the rice field is one of the most common abiotic stresses, reducing crop productivity, especially at reproductive stage, which is very sensitive to salt stress. The aim of this investigation was to study mRNA-related Na+ uptake/translocation and Na+ enrichment in the cellular level, leading to physiological changes, growth characteristics, and yield attributes in FL530 [salt-tolerant genotype; carrying SKC1 (in relation to high-affinity potassium transporters controlling Na+ and K+ translocation) and qSt1b (linking to salt injury score) QTLs] and KDML105 (salt-sensitive cultivar; lacking both QTLs) parental lines and 221-48 (carrying SKC1 and qSt1b QTLs) derived from BILs (backcross introgression lines) at 50% flowering of rice, under 150-mM NaCl until harvesting process. The upregulation of OsHKT1;5 (mediating Na+ exclusion into xylem parenchyma cells) and OsNHX1 (Na+/H+ exchanger to secrete Na+ into vacuole) and downregulation of OsHKT2;1 and OsHKT2;2 (mediating Na+ restriction in the roots, leaf sheath and older leaves) in cvs. FL530 and 221-48 (+ SKC1; + qSt1b) under salt stress were observed. It restricted Na+ level in flag leaf, thereby preventing salt toxicity, as indicated by maintenance of photon yield of PSII (ΦPSII), net photosynthetic rate (Pn), transpiration rate (E) and overall growth performances. In contrast, Na+ enrichment in flag leaf of cv. KDML105 (-SKC1;-qSt1b) caused the reduction in ΦPSII by 30.5% over the control, leading to the reduction in Pn by 62.3%, in seed sterility by 88.2%, and yield loss by 85.1%. Moreover, the negative relationships between Na+ enrichment in flag leaf, physiological changes, and yield traits in rice crop grown under salt stress were demonstrated. Based on this investigation, rice genotype 221-48 was found to possess salt-tolerant traits at reproductive stage and thus could prove to be a potential candidate for future breeding programs.

Physiological Evaluation of Different Rice Genotypes to Two Salinity Level during Seedling Stage under Hydroponic System

Hydroponics study was conducted to screen eight rice genotypes (CO 51, ADT 53, ADT 37, IR 64, CO 43, ASD 16, Pokkali; TRY 3) under salinity stress on early seedling stage. Two Saline treatments (75 and 100 mM NaCl) were given at 15 days old seedling; observations were recorded at 10 days after salt stress. Results showed that shoot length, root length, total fresh and dry weight, shoot and root fresh weight, shoot and root dry weight and root- shoot ratio were reduced under saline conditions compared to control. Na+ ion Concentration and Na+/ k+ ratio was higher in saline treatments than control. However, K+ ion absorption decreased with increasing salinity level. Electrolyte leakage and osmotic potential had increasing trend with increasing level of salinity. In this study, rice genotypes Pokkali, TRY 3 and CO 43 perform as tolerant; CO 51, ADT 53 and ASD 16 perform as moderately tolerant; ADT 37 is susceptible and IR 64 is highly susceptible. This type of study is required to develop salt tolerant genotypes at salt stress during seedling stage; to increase the growth and yield of rice there by satisfy the need of country’s requirement.

Physio-morphological and molecular analysis for salt tolerance in chickpea (Cicer arietinum)

After drought salinity is the major abiotic stress that severely affects agricultural productivity globally. Chickpea (Cicer arietinum L.) is the important grain legume which suffers approximately 8-10% of total global yield loss due to salinity. Screening for salt stress is difficult and traits that correlate salinity tolerance are least understood. The present study was carried out at ICAR-IARI, New Delhi 2017-18, deals with the important morphological and physiological traits like RWC (Relative water content), EL (Electrolyte Leakage), Na/K (sodium and potassium ratio) to characterize the salt tolerant genotypes under hydroponic condition which is a quick and easy method to screen large number of chickpea genotypes at initial stage under salt stress condition. Genotypes showing high RWC, low EL and Na/K ratio were tolerant like ICCV 10, JG 11, JG 62 and CSG-8962 whereas genotypes like ICC4958 and Pusa362 fall under moderately tolerant genotypes and DCP 93-3, Pusa 256, Phule G5 and SBD 377 were classified as susceptible genotypes. This study also attempts to understand the candidate genes responsible for salt-stress related pathways in chickpea genotypes based on sequence similarity approach exploiting known salt-stress responsive genes from model crops or other crop species.

Appraisal of Salt Tolerance under Greenhouse Conditions of a Cucurbitaceae Genetic Repository of Potential Rootstocks and Scions

Soil salinization due to climate change and intensive use of water and soil is increasing exponentially. Cucurbitaceae species are cultivated worldwide and the identification of salinity tolerant genotypes to be used as rootstock or scion for securing yield stability in salt affected agricultural areas is a research priority. In the present greenhouse study, we assessed the response to salinity (0 mM a non-salt control and 150 mM NaCl dissolved in the nutrient solution) in the seedlings of 30 genotypes of cucurbits grown in a floating hydroponic system. The species tested included 16 genotypes of Cucumis melo L. (CM1-16), 6 Citrullus vulgaris Schrad. (CV1-6), 2 interspecific hybrids of Cucurbita maxima Duch. × Cucurbita moschata Duch. (CMM-R1 and 2), 4 bottle gourd (Lagenaria siceraria (Molina) Standl. (LS1-4)), 1 Cucurbita moschata Duch. (CMO51-17), and 1 luffa (Luffa cylindrica Mill. (LC1)) species. Results highlighted different morphological and physiological traits between the species and genotypes and a different response to salt stress. We identified C. maxima × C.moscata interspecific hybrid CMM-R2, melon genotypes CM6, CM7, CM10, and CM16 together with watermelon genotypes CV2 and CV6 and bottle gourd LS4 as salt tolerant genotypes and possible candidates as salt resistant rootstock to be introduced in grafting programs.

Saline water irrigation strategies in two production cycles of naturally colored cotton

Scarcity of good quality water is a limiting factor for irrigated agriculture, especially in a semi-arid region, which induces the use of waters with high salt levels to irrigate crops. As a result, it becomes necessary to use salt tolerant genotypes and appropriate cultivation strategies that enable their production. With this focus, this study was carried out to evaluate the production components of three naturally colored cotton genotypes (‘BRS Rubi’, ‘BRS Topazio’, and ‘BRS Safira’), subjected to various irrigation management strategies, varying the stages of development in which plants were irrigated with saline water. The study also aimed to evaluate the influence of the water salinity level at which seeds were formed, in a new production cycle, using the same irrigation strategies and varying the phenological stages. There were seven salinity management strategies in the first year of cultivation and ten in the second year, both experiments were conducted in a randomized block design. Among the genotypes, ‘BRS Rubi’ was the most tolerant to salinity, with respect to the intrinsic characteristics of the fiber, regardless of the development stage. In the second production cycle, plants grown from seeds formed under salt stress during the stages of flowering and yield formation had increases in lint weight and fiber quality. In the second year, the oil content of the cotton genotypes was not compromised by the cumulative salt stress, considering seeds produced in plants irrigated with saline water in the previous cycle.

Effect of Salinity on Seed Germination and Seedling Development of Sorghum (Sorghum bicolor (L.) Moench) Genotypes

Salinity is one of the most important abiotic stresses that negatively affects plant growth and development around the world. It has been reported that approximately 19.5% of all irrigated land and 2.1% of dry land is affected by salt stress, and these percentages continue to increase. Sorghum, a C4 plant, is the fifth most important cereal in the world. Numerous studies reported that there are high genetic variations in sorghum. These genetic variations can be monitored to search for the most salt-tolerant genotypes. Therefore, the aim of our study was to investigate the responses of ten sorghum genotypes to different levels of salinity. We focused on germination and seedling growth as the most critical stages of plant development. In our research we included germination percentage, germination index, mean germination time, seedling vigor index, seedlings’ shoot and root lengths, fresh and dry seedling weight, and salinity tolerance indices. For data assessment we applied two-way ANOVA, non-metric multidimensional scaling, and hierarchical agglomerative classification. Our results demonstrate that salinity was responsible for 98% of the variation in assessed parameters, whereas genotype effect accounted for only 2% of the documented variation. It can be concluded that seedling traits can be used as a valid criterion for the selection of genotypes with a better tolerance to salinity stress.

Evaluation of Physiological and Biochemical Parameters of Some Wheat (Triticum aestivum) Genotypes under Salinity Stress

Physiological and biochemical parameters of plants among five wheat genotypes: KH-65, KRL-210, KRL-99, PBW-343 and PBW-373 were studied. Wheat plantlets, at three-leaf stage, were supplemented with 0, 50, 100, 150, 200, 250 and 300 mM of NaCl for 48 hours. Principal component analysis revealed chlorophyll and carotenoid degradation as best salinity indicator for studied wheat genotypes. Salt tolerance levels of studied wheat genotypes were in the order: KH-65 greater than KRL-210 greater than KRL-99 greater than PBW-343 greater than PBW-373. The study has revealed that observed physiological and biochemical data may provide an insight into the existence of internal mechanism in salt tolerant genotypes to cope up with salinity stress.

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity