Salt-tolerant Varieties Research Articles

Natural variation in salt tolerance

Plant Science Salt stress in agriculture is not just a matter of being near the ocean; as much as half of irrigated farmland is overly salty. Plants have strategies to adjust to saline conditions, such as reducing sodium uptake or altering the architecture of their root systems. Julkowska et al. analyzed a range of Arabidopsis thaliana genotypes to identify genetic loci that could drive changes in root architecture in response to salt. Natural variation across 347 A. thaliana accessions affected the angle of roots and the distribution of bulk between main and lateral roots, leading to identification of the genes responsible. For example, variation in gene expression in response to salt showed that the CYP79B2 (cytochrome P450 family 79 subfamily B2) gene serves to reduce lateral root growth in salt-stressed conditions. Plant Cell 29 , 3198 (2017).

Seed Hydropriming Enhances Osmotic Stress Tolerance Potential in Vigna radiata

Green gram (Vigna radiata (L.) Wilczek) is a widely cultivated pulse crop in India, and it holds a key importance in food supplement due to its protein-rich edible seeds. This crop usually experiences abiotic stresses like drought and salinity during the cultivation period. The investigation was carried out to study the effect of hydropriming on osmotic stress tolerance potential of three Vigna radiata varieties, with varied abiotic stress tolerance potential. Hydropriming enhances the photosynthetic activities of the seedlings. Moreover, hydropriming resulted in reduction of proline content in Pusa Ratna and Pusa 9531 seedlings, whereas the salt-tolerant variety Pusa Vishal showed increase in proline content, especially under stressed conditions. Osmotic stress caused increase in MDA content in all the varieties studied, and this increase was significantly minimized by the influence of hydropriming. Hydropriming also enhanced the activities of antioxidant enzymes in the seedlings. From the results of this study, it is concluded that hydropriming of seeds improved the drought and salinity stress tolerance potential of all the three green gram varieties and it was significantly evident in the abiotic stress-sensitive variety Pusa Ratna as compared to Pusa 9531 (drought tolerant) and Pusa Vishal (NaCl tolerant).

Stress Inducible Overexpression of AtHDG11 Leads to Improved Drought and Salt Stress Tolerance in Peanut (Arachis hypogaea L.).

Peanut is an important oilseed and food legume cultivated as a rain-fed crop in semi-arid tropics. Drought and high salinity are the major abiotic stresses limiting the peanut productivity in this region. Development of drought and salt tolerant peanut varieties with improved yield potential using biotechnological approach is highly desirable to improve the peanut productivity in marginal geographies. As abiotic stress tolerance and yield represent complex traits, engineering of regulatory genes to produce abiotic stress-resilient transgenic crops appears to be a viable approach. In the present study, we developed transgenic peanut plants expressing an Arabidopsis homeodomain-leucine zipper transcription factor (AtHDG11) under stress inducible rd29A promoter. A stress-inducible expression of AtHDG11 in three independent homozygous transgenic peanut lines resulted in improved drought and salt tolerance through up-regulation of known stress responsive genes (LEA, HSP70, Cu/Zn SOD, APX, P5CS, NCED1, RRS5, ERF1, NAC4, MIPS, Aquaporin, TIP, ELIP) in the stress gene network, antioxidative enzymes, free proline along with improved water use efficiency traits such as longer root system, reduced stomatal density, higher chlorophyll content, increased specific leaf area, improved photosynthetic rates, and increased intrinsic instantaneous WUE. Transgenic peanut plants displayed high yield compared to non-transgenic plants under both drought and salt stress conditions. Holistically, our study demonstrates the potentiality of stress-induced expression of AtHDG11 to improve the drought, salt tolerance in peanut.

Elucidating the role of osmotic, ionic and major salt responsive transcript components towards salinity tolerance in contrasting chickpea (Cicer arietinum L.) genotypes.

The growth of chickpea (Cicer arietinum L.) is extremely hampered by salt stress. Understanding of physio-biochemical and molecular attributes along with morphological traits contributing to the salinity tolerance is important for developing salt tolerant chickpea varieties. To explore these facts, two genotypes CSG8962 and HC5 with contrasting salt tolerance were evaluated in the salinity stress (Control and 120mM NaCl) conditions. CSG8962 maintained lower Na/K ratio in root and shoot, trammeled Na translocation to the shoots from roots compared to HC5 which ascribed to better exclusion of salt from its roots and compartmentation in the shoot. In chickpea, salt stress specifically induced genes/sequences involved at several levels in the salt stress signaling pathway. Higher induction of trehalose 6 phosphate synthase and protein kinase genes pertaining to the osmotic and signaling modules, respectively, were evident in CSG8962 compared to HC5. Further transcripts of late embryogenesis abundant, non-specific lipid transfer protein, HI and 219 genes/sequences were also highly induced in CSG8962 compared to HC5 which emphasizes the better protection of cellular membranous network and membrane-bound macromolecules under salt stress. This further suppressed the stress enhanced electrolyte leakage, loss of turgidity, promoted the higher compatible solute accumulation and maintained better cellular ion homoeostasis in CSG8962 compared to HC5. Our study further adds to the importance of these genes in salt tolerance by comparing their behavior in contrasting chickpea genotypes.

Allocation of Macronutrients in Roots, Sheaths, and Leaves Determines Salt Tolerance in Rice

To determine useful parameters for salt tolerance in rice and selection of salt-tolerant varieties, their macronutrient contents in roots, sheaths, and leaves were evaluated under salt stress condition. A hydroponic experiment was conducted to evaluate 29 rice varieties for salt tolerance. The salt stress treatment included an artificial seawater solution (electrical conductivity of 12 dS·m-1). After a 2-week period of salt stress, standard evaluation scores (SES) of visual injuries for salt stress were assessed. In addition, we measured the contents of N, P, K, Na, Mg, and Ca in roots, sheaths, and leaves. The results showed that differences in macronutrients in the different plant tissues correlated with rice tolerance to the salt stress condition. Under the control treatment, salt-tolerant varieties exhibited low K content in root. Under the salt stress treatment, the salt-tolerant varieties exhibited low SES, high N content in leaves and sheaths, low Na content in leaves and sheaths, low Mg content in leaves and sheaths, and low Ca content in sheaths. The salt-tolerant varieties also exhibited high salt stress treatment/control treatment (ST/CT) ratios for dry matter in sheaths, N content in leaves and sheaths, and K content in sheaths, and low Na/K ratios in leaves and sheaths. Therefore, these parameters might be useful to understand salt tolerance in rice.

Screening wild progenitors of wheat for salinity stress at early stages of plant growth: insight into potential sources of variability for salinity adaptation in wheat

Wild relatives of wheat have served as a pool of genetic variation for understanding salinity tolerance mechanisms. Two separate experiments were performed to evaluate the natural diversity in root and shoot Na+ exclusion and K+ accumulation, and the activity of four antioxidant enzymes within an extensive collection of ancestral wheat accessions. In the initial screening experiment, salinity stress (300 mm NaCl) significantly increased Na+ concentration in roots and leaves and led to a significant decline in root and shoot fresh weights, dry weights, and K+ contents. Principal component analysis of the 181 accessions and 12 species identified three first components accounted for 63.47% and 78.55% of the variation under salinity stress. We identified 12 accessions of each species with superior tolerance to salinity for further assessment of their antioxidant defence systems in response to salinity. Both mild (250 mm NaCl) and severe (350 mm NaCl) levels of salinity significantly increased activities of four enzymes, indicating an enhanced antioxidant-scavenging system for minimising the damaging effects of H2O2. Some of the wild relatives—Aegilops speltoides (putative B genome), Ae. caudata (C genome), Ae. cylindrica (DC genome) and Triticum boeoticum (Ab genome)—responded to salinity stress by increasing antioxidants as the dominant mechanism to retain oxidative balance in cells. Further evaluation of salt-tolerance mechanisms in these superior wild relatives will help us to understand the potential of wheat progenitors in the development of more salt-tolerant varieties.

Performance of Salt Tolerant Wheat Varieties in Salt Affected Soils

Performance of Salt Tolerant Wheat Varieties in Salt Affected Soils

Evaluation of saltol introgressed back cross inbred lines for salinity tolerance in rice (Oryza sativa L.)

Fifty one backcross inbred lines (BC3F3 population) of ADT 37 introgressed with saltol loci from FL478 controlling salinity tolerance in rice and 17 lines of CR 1009 Sub1 introgressed with saltol loci from FL478 were evaluated for their salinity tolerance along with respective recurrent parents. All 68 backcross inbred lines (BIL) were subjected to genotyping using RM3412 which led to the identification of 20 lines in the genetic background of ADT 37 and 12 lines in the genetic background of CR 1009 harboring saltol loci from FL478. Seedlings of all 32 positive progenies were subjected to phenotypic evaluation under hydroponic conditions (EC levels of 6 dSm−1 and EC 12 dSm−1) by following IRRI's standard protocol (1–9 scale scoring). Out of 32 selected BILs, 14 lines were found to be tolerant and remaining 18 lines were identified to be moderately tolerant. Tolerant lines exhibited very less reduction in their root growth with increased salinity level. Among the tolerant lines, minimum root and shoot length reduction was observed in BIL 1102, BIL 1079 and BIL 1091 at EC 6 dSm−1 level. At EC 12 dSm−1, minimum root and shoot length reduction was observed in BIL 33, BIL 44, BIL 772, BIL 1079, BIL 1091, BIL 1096, BIL 1101 and BIL 1102. Saline tolerant lines viz., BIL 33, BIL 1094, BIL 1096 and BIL 1101 have recorded maximum uptake of K+ in both root and shoot which resulted in low Na+/K+ ratio. The salt tolerant lines identified in this study will be further evaluated in saline soil under different locations to develop salt tolerant varieties.

ITRAQ-Based Comparative Proteomic Analysis of Seedling Leaves of Two Upland Cotton Genotypes Differing in Salt Tolerance

Cotton yields are greatly reduced under high salinity stress conditions, although cotton is considered a moderately salt-tolerant crop. Understanding at the molecular level how cotton responds to salt stress will help in developing salt tolerant varieties. Here, we combined physiological analysis with isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics of seedling leaves of 2 genotypes differing in salinity tolerance to 200 mM (18.3 dS/m) NaCl stress. Salt stress produced significant stress symptoms in the sensitive genotype Nan Dan Ba Di Da Hua (N), including lower relative water and chlorophyll contents and higher relative electrolyte leakage and Na+/K+ ratio in leaf samples, compared with those in the tolerant genotype Earlistaple 7 (Z). A total of 58 differentially abundant salt-responsive proteins were identified. Asp-Glu-Ala-Asp (DEAD)-box ATP-dependent RNA helicase 3 and protochlorophyllide reductase were markedly suppressed after salt treatment, whereas the phosphate-related differentially abundant proteins (DAPs) phosphoethanolamine N-methyltransferase 1 and 14-3-3-like protein E were induced, and all these proteins may play significant roles in salt stress. Twenty-nine salt-responsive proteins were also genotype specific, and 62.1 and 27.6% of these were related to chloroplast and defense responses, respectively. Based on the Arabidopsis thaliana protein interaction database, orthologs of 25 proteins showed interactions in Arabidopsis, and among these, a calmodulin protein was predicted to have 212 functional partners. In addition, the Golgi apparatus and calcium may be important for salt secretion in cotton. Through integrative proteome and transcriptome analysis, 16 DAPs were matched to differentially expressed genes and verified using qRT-PCR. On the basis of these findings, we proposed that some proteins related to chloroplast, ATP, ribosomal, and phosphate metabolism as well as to the Golgi apparatus and calcium may play key roles in the short-term salt stress response of cotton seedling leaves.

Application of Ash for Amelioration of Salinity Effect in Rice

Agricultural land use in coastal area covers 53% and the lands are mostly affected by salinity. Besides, the average yield of rice in these areas is very low due to salinity. Although, BRRI has developed salt registrant rice varieties, the average production can be improved through soil management. Thus, a pot experiment was conducted in the net house of Department of Agronomy, Bangladesh Agricultural University, Mymensingh, during March to August 2010 to investigate the ameliorative effect of ash application on yield and yield attributes of rice under various salinity levels. Rice var. BRRI dhan47 (a salt tolerant variety) was used in the experiment. The sodium chloride induced salinity levels were 20, 40, 60, 80 and 100 mM NaCl and the levels of ash applied were 1.5, 3, 4.5 and 6 t ha-1. Results revealed that the different levels of salinity had significant adverse effect on plant height, tillers hill-1, panicle hill-1, grains panicle-1, 1000-grain weight, grain yield, biological yield and harvest index. All the plants eventually died when they were exposed to salinity level of 40 mM NaCl or more and could not survive up to maturity. Application of ash enhanced the yield attributes and yield of rice under different salinity levels compared to those without ash. It was concluded that application of ash at the rate of 6 t ha-1 ameliorated the salinity stress effect on rice yield of BRRI dhan47.Bangladesh Agron. J. 2017, 20(1): 31-36

Towards Developing Salinity Tolerant Rice Adaptable for Coastal Regions in Indonesia

Lowland rice areas along the coastal regions are a major contributor for rice production in Indonesia. Sustainability of rice production in those areas is challenged by the increase of soil salinity as the result of sea water inundation. The problem is exacerbated by the increase of sea water level as the impact of global climate change. High concentration of salt ion in the soil could significantly reduce rice growth and yield. Development of salinity tolerant rice varieties is therefore important to maintain sustainability of rice production in the coastal regions. Breeding programs to improve salinity tolerance of Indonesian rice has been established in Indonesian Centre for Rice Research. Through intensive salt tolerant screening program genetic variations in salinity tolerance have been identified within rice germplasm allowing the improvement of salinity tolerant of existing rice varieties. Different genetic resources have been used for salinity tolerant improvement including landraces, improved varieties and introduction lines. A number of promising salt tolerant rice breeding lines have been developed and showed adaptability to salt affected areas in the lowland coastal areas. Two new salt tolerant rice varieties have been released recently which are adaptable to salt affected areas. This paper will describe the progress in the breeding programs to develop salt tolerant rice for lowland rice areas in the coastal regions. Strategy to accelerate the improvement of the salinity tolerant of Indonesian rice varieties in the future will be also discussed.Keywords: rice, breeding, salinity tolerance, coastal regions.

A retrotransposon in an HKT1 family sodium transporter causes variation of leaf Na+ exclusion and salt tolerance in maize.

Soil salinity is one of several major abiotic stresses that constrain maize productivity worldwide. An improved understanding of salt-tolerance mechanisms will thus enhance the breeding of salt-tolerant maize and boost productivity. Previous studies have indicated that the maintenance of leaf Na+ concentration is essential for maize salt tolerance, and the difference in leaf Na+ exclusion has previously been associated with variation in salt tolerance between maize varieties. Here, we report the identification and functional characterization of a maize salt-tolerance quantitative trait locus (QTL), Zea mays Na+ Content1 (ZmNC1), which encodes an HKT-type transporter (designated as ZmHKT1). We show that a natural ZmHKT1 loss-of-function allele containing a retrotransposon insertion confers increased accumulation of Na+ in leaves, and salt hypersensitivity. We next show that ZmHKT1 encodes a plasma membrane-localized Na+ -selective transporter, and is preferentially expressed in root stele (including the parenchyma cells surrounding the xylem vessels). We also show that loss of ZmHKT1 function increases xylem sap Na+ concentration and causes increased root-to-shoot Na+ delivery, indicating that ZmHKT1 promotes leaf Na+ exclusion and salt tolerance by withdrawing Na+ from the xylem sap. We conclude that ZmHKT1 is a major salt-tolerance QTL and identifies an important new gene target in breeding for improved maize salt tolerance.

Plant salt-tolerance mechanism: A review

Almost all crops that are important to humans are sensitive to high salt concentration in the soil. The presence of salt in soil is one of the most significant abiotic stresses in farming. Therefore, improving plant salt tolerance and increasing the yield and quality of crops in salty land is vital. Transgenic technology is a fast and effective method to obtain salt-tolerant varieties. At present, many scholars have studied salt damage to plant and plant salt-tolerance mechanism. These scholars have cloned a number of salt-related genes and achieved high salt tolerance for transgenic plants, thereby showing attractive prospects.In this paper, the salt-tolerance mechanism of plants is described from four aspects: plant osmotic stress, ion toxicity, oxidative stress, and salt tolerance genes. This review may help in studies to reveal the mechanism of plant salt tolerance, screen high efficiency and quality salt tolerance crops.

Effects of acute salt stress on modulation of gene expression in a Malaysian salt-tolerant indigenous rice variety, Bajong.

The small genome size of rice relative to wheat and barley, together with its salt sensitivity, make it an ideal candidate for studies of salt stress response. Transcriptomics has emerged as a powerful technique to study salinity responses in many crop species. By identifying a large number of differentially expressed genes (DEGs) simultaneously after the stress induction, it can provide crucial insight into the immediate responses towards the stressor. In this study, a Malaysian salt-tolerant indigenous rice variety named Bajong and one commercial rice variety named MR219 were investigated for their performance in plant growth and ion accumulation properties after salt stress treatment. Bajong was further investigated for the changes in leaf's transcriptome after 6h of stress treatment using 100mM NaCl. Based on the results obtained, Bajong is found to be significantly more salt tolerant than MR219, showing better growth and a lower sodium ion accumulation after the stress treatment. Additionally, Bajong was analysed by transcriptomic sequencing, generating a total of 130 millions reads. The reads were assembled into de novo transcriptome and each transcript was annotated using several pre-existing databases. The transcriptomes of control and salt-stressed samples were then compared, leading to the discovery of 4096 DEGs. Based on the functional annotation results obtained, the enrichment factor of each functional group in DEGs was calculated in relation to the total reads obtained. It was found that the group with the highest gene modulation was involved in the secondary metabolite biosynthesis of plants, with approximately 2.5% increase in relation to the total reads obtained. This suggests an extensive transcriptional reprogramming of the secondary metabolic pathways after stress induction, which could be directly responsible for the salt tolerance capability of Bajong.

EFFECT OF DIFFERENT CALCIUM CONCENTRATIONS IN SOIL ON SURVIVAL PERCENT AND UPTAKE OF Na+ AND Cl- IONS BY RICE PLANT

Salinity is a stress factor affecting the production of crop in many regions. Calcium can reduce Na+ transport to shoots in rice. Two greenhouse experiments were conducted in Faculty of Agriculture, Cairo University, Egypt, during 2015 growing season of rice to evaluate the effect of different calcium concentrations on survival percent along with uptake of Na+ and Cl- ions by two varieties of rice (Oryza sativa L.) differing in salt-tolerance. The first experiment was undertaken to study the effect of different calcium concentrations on survival percent of IR28 (salt-sensitive) and Nona Bokra (Salt-tolerant) seedlings which were transferred to salinized nutrient solution containing 0.5% NaCl and a variable calcium concentrations at 4, 40, 100 and 200 ppm; plants were grown up to 40 days. The second experiment investigated the effect of different calcium concentrations on growth, uptake and transport of Na+ and Cl- ions in the two rice varieties differing in salt-tolerance. The seedlings were transferred to salinized nutrient solution containing 0.5% NaCl and calcium ion concentrations at two levels, 4 and 40 ppm. Plants were harvested at 0, 1, 3, 5 and 7 days from salinization. The results indicated that the salt-tolerant variety (Nona Bokra) survived for more than 40 days under exposure to 0.5% NaCl when calcium concentration of the culture solution ranged from 40 to 200 ppm Ca++. The low calcium ion concentration (4 ppm) depressed the growth of plants at 5 and 7 days after salinization. In Nona Bokra, the shoot had less sodium and Cl than the root. This implies that the salt tolerance of Nona Bokra may be attributed to the restricted translocation of Na+ and Cl- from the root to the shoot. Sodium as well as cloride content in the shoot of IR28 was more than twice that of Nona Bokra. An adequate amount of Ca+2 tended to lower the salt injury caused by high levels of salinity in rice plants. The effect of calcium ion on salt tolerance varied greatly between Nona Bokra and IR28 varieties.

NONOSMOTIC EFFECT OF POLYETHYLENE GLYCOL ON PERCENT SURVIVAL AND GROWTH OF RICE

Salinity is one of the major environmental factors limiting crop productivity. For this reason, two greenhouse experiments were conducted in Faculty of Agriculture, Cairo University, Egypt, during the year 2015 using two rice varieties to evaluate the effects of various levels of osmotic stress caused by polyethylene-glycol 6000 (PEG) and NaCl. Furthermore, it was tested whether the inhibitory effect of salinity on growth, sodium and chloride concentration by two different varieties was greater under NaCl or PEG treatment. The first experiment was undertaken to separate osmotic and ionic aspects of salinity damage to rice (Oryza sativa L.).Seedlings of IR28 (salt-sensitive) and Nona Bokra (salt-tolerant) rice varieties were transferred to salinized nutrient solution containing 85 mol m-3NaCl (-3.0 bars) with or without PEG 6000 (-2.0 bars, 45 gL-1). Plants were grown up to 30 days in the salinized solutions. The second experiment was designed to determine the effect of salinity (85 mol m-3NaCl) with or without PEG 6000 (-0.5 bar, 11 g L-1)on growth, uptake and transport of sodium and chloride in two rice varieties differing in salt tolerance. The results indicated that survival of salt-tolerant variety (Nona Bokra) was increased significantly by adding PEG (-2.0 bars). The addition of PEG also reduced the rate of death of rice plants compared with NaCl alone. Also, data showed that PEG 6000 (0.5 bar, 11 gL-1) reduce sodium concentration in root of IR28 and Nona Bokra but its effect upon sodium concentration in shoot of the two varieties was more pronounced than the reduction of Na+ concentration in root. Highly significant differences were obtained between zero and 11 gL-1 PEG. The result of this study is strongly indicated that addition of PEG dramatically lessened the toxicity of NaCl to rice seedlings.

Genetic Dissection of Seedling Stage Salinity Tolerance in Rice Using Introgression Lines of a Salt Tolerant Landrace Nona Bokra.

Salinity is an important abiotic stress affecting rice production worldwide. Development of salt tolerant varieties is the most feasible approach for improving rice productivity in salt affected soils. In rice, seedling stage salinity tolerance is crucial for better crop establishment. Quantitative trait loci (QTL) mapping using introgression lines (ILs) is useful for identification and simultaneous transfer of desirable alleles into elite genetic background. In the present study, 138 ILs derived from the cross between a high yielding elite salt susceptible japonica rice cultivar Jupiter and a salt tolerant indica landrace Nona Bokra were evaluated for salt tolerance at seedling stage in a hydroponics experiment and were genotyped using 126 simple sequence repeat markers. A total of 33 additive QTLs were detected by composite interval mapping for 8 morphophysiological traits. The phenotypic responses, genomic composition, and QTLs identified from the study indicated that Na/K ratio is the key factor for salinity tolerance. The mechanisms of tolerance might be due to homeostasis between Na+ and K+ or Na+ compartmentation. Gene ontology (GO) analysis revealed that significant GO terms in the selected QTL regions were associated with the genes/pathways involved in signaling, enzyme inhibition, and ion transport. Because majority of QTLs are with small effects, marker-assisted recurrent selection is proposed to accumulate favorable alleles for improving salt tolerance using the tolerant ILs identified in this study. The tolerant ILs also provide an opportunity for functional genomics studies to provide molecular insights into salt tolerance mechanisms in Nona Bokra.

Sodium exclusion is a reliable trait for the improvement of salinity tolerance in bread wheat

ABSTRACTIdentification of novel wheat (Triticum aestivum L.) germplasm is imperative to develop salt tolerant varieties. In the first phase, 400 accessions were screened against high salt stress (200 mM NaCl) on the basis of Na+ accumulation in leaf blade, and 40 genotypes with contrast reaction to salinity were selected. Salt tolerant group (25 genotypes) had higher leaf K+/Na+ ratio, maximum root and shoot lengths, leaf fresh/dry weights and chlorophyll content as compared to the salt sensitive group (15 genotypes). In second phase, physiologically based screening was performed on selected genotypes against varying salinity levels (0, 100 and 200 mM NaCl). GGE biplot analysis indicates that genotypes TURACO, V-03094, V0005, V-04178, Kharchia 65 and V-05121 were the most salt-tolerant and declared winners as depicted by more gaseous exchange relations and growth potential which was strongly correlated with proper Na+, K+ discrimination in leaf and root tissues. Genotypes PBW343*2, NING MAI 50, PGO, PFAU, V-04181, PUNJAB 85, KIRITATI, TAM200/TUI and TAM200 were poor performer due to more Na+ accumulation in leaf ultimately retarded growth. In conclusion, low Na+ accumulation in leaf can be used as the best screening criteria, employing a large set of genotypes in a breeding program.

Metabolomics analysis of rice responses to salinity stress revealed elevation of serotonin, and gentisic acid levels in leaves of tolerant varieties

ABSTRACTA GC-MS based analytical approach was undertaken to understand the metabolomic responses of seedlings of 2 salt sensitive (Sujala and MTU 7029) and 2 tolerant varieties (Bhutnath, and Nonabokra) of indica rice (Oryza sativa L.) to NaCl induced stress. The 4 varieties responded differently to NaCl treatment with respect to the conserved primary metabolites (sugars, polyols, amino acids, organic acids and certain purine derivatives) of the leaf of rice seedlings. However, there were significant differences in salt induced production of chorismic acid derivatives. Serotonin level was increased in both the salt tolerant varieties in response to NaCl induced stress. In both the salt tolerant varieties, increased production of the signaling molecule gentisic acid in response to NaCl treatment was noticed. Salt tolerant varieties also produced increased level of ferulic acid and vanillic acid. In the salt sensitive varieties, cinnamic acid derivatives, 4-hydroxycinnamic acid (in Sujala) and 4-hydroxybenzoic acid (in MTU 7029), were elevated in the leaves. So increased production of the 2 signaling molecules serotonin and gentisic acid may be considered as 2 important biomarker compounds produced in tolerant varieties contributing toward NaCl tolerance.

Review on sugar beet salt stress studies in Iran

Increase of saline lands in most regions of the world and Iran, limit of production increase based on land enhancement and also threat of saline water and soils for crop production make related researches and production of salt tolerant variety to be more serious. There have been many researches about salt stress in Sugar Beet Seed Institute of Iran (SBSI) during several years. Accordingly, the new screening methods for stress tolerance to be continued based on these researches. Previous researches in SBSI were reviewed and results concluded to this study which is presented in this article in three categories including: Agronomy, Breeding and Biotechnology. In agronomy researches, suitable planting medium, EC, growth stage and traits for salinity tolerance screening were determined and agronomic technique such as planting date, planting method and suitable nutrition for sugar beet under salt stress were introduced. Sand was salinizied by saline treatments two times more than Perlit so large sized Perlit is suitable medium for saline studies. Sugar beet genotypes screening for salt tolerance and should be conducted at EC=20 in laboratory and EC= 16 dS/M in greenhouse. Although sugar beet seed germination has been known as more susceptible stage to salinity, it seems establishment is more susceptible than germination in which salinity will cause 70-80% decrease in plant establishment. Measurements of leaves Na, K and total carbohydrate at establishment stage would be useful for faster screening of genotypes, based on high and significant correlation of these traits at establishment with yield at harvest time. In breeding section, SBSI genotypes with drought tolerance background would be useful for salinity stress studies and finally there is a need for more research in the field of biotechnology in Iran.