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Wheat genotype Kharchia is a donor for salt tolerance in wheat breeding programs worldwide; however, the tolerance mechanism in Kharchia is yet to be deciphered completely. To avoid spending energy on accumulating organic osmolytes and to conserve resources for maintaining growth, plants deploy sodium (NaThe online version contains supplementary material available at 10.1007/s12298-022-01237-w.

The rise in atmospheric CO2 levels impacts humankind by threatening food and nutritional security. The strong correlation between crop yield and grain weight in cereals is an essential component of yield stability. Further, improving grain protein and mineral nutrient content is a crucial breeding target for cereal crops. The study was performed to understand the interactive effects of elevated CO2 (EC) and nitrogen (N) fertilization on grain ionome, grain yield parameters, grain morphology, and the expression of genes related to grain morphology. The changes in ionome and grain parameters were examined in response to two N levels optimal N (ON: 500 mg/pot) and high N (HN: 625 mg/pot) along with atmospheric CO2 enrichment [ambient (CO2) of 400 ±10 ppm and elevated (CO2) of 700 ±10 ppm]. Grain ionome (N, K, Ca and Fe) showed a general decrease in EC-grown wheat plants. The expression of genes related to grain length (TaGL3 and TaGL7) were upregulated, and those genes related to grain width (TaGW2 and TaGW6) were downregulated under EC in maturing spikelet of wheat. In the case of TaSnRK2, the expression was promoted by EC in HN treatment. The complex regulation of source and sink-associated gene transcript abundance indicates an EC mediated alteration in N and sugar signalling in wheat.

Nitrogen (N) recognized as a critical element for plant growth plays a fundamental role in rice cultivation. The N use efficiency (NUE) hovers around 30-35% in rice, suggesting a significant loss of N from the rice fields. Improving the NUE therefore would require genetic interventions and breeding. The cultivar improvement for N uptake and utilization is required to elevate NUE to further heights. Several quantitative trait loci (QTLs) for NUE under varying conditions and genetic backgrounds have been reported in rice. Consolidation of this distributed and unorganized information is necessary to identify critical genomic regions to be used for crop improvement. Therefore, a Meta-analysis from an assembly of 506 QTLs reported from 18 different studies was performed to identify the most significant genomic regions associated with NUE in rice. A total of 12 meta-QTLs (mQTLs) related to the traits such as NUE and grain yield per plant under N deficit conditions have been identified over four rice chromosomes namely 1, 3, 4, and 8. Evaluation of these mQTLs in a set of Indian rice germplasm revealed a significant association of the meta loci with N use parameters and showed wide distribution in the germplasm. Identification of mQTLs on different chromosomes together with their respective markers will help recruit them in marker-assisted selection (MAS) to develop N use efficient genotypes.

Plant's stomatal physiology and anatomical features are highly plastic and are influenced by diverse environmental signals including the concentration of atmospheric CO2 and nutrient availability. Recent reports suggest that the form of nitrogen (N) is a determinant of plant growth and nutrient nitrogen use efficiency (NUE) under elevated CO2 (EC). Previously, we found that high nitrate availability resulted in early senescence, enhanced reactive oxygen species (ROS), and reactive nitrogen species (RNS) production and also that mixed nutrition of nitrate and ammonium ions were beneficial than sole nitrate nutrition in wheat. In this study, the interactive effects of different N forms (nitrate, ammonium, mixed nutrition of nitrate, and ammonium) and EC on epidermal and stomatal morphology were analyzed. Wheat seedlings were grown at two different CO2 levels and supplied with media devoid of N (N0) or with nitrate-N (NN), mixed nutrition of ammonium and nitrate (MN), or only ammonium-N (AN). The stoma length increased significantly in nitrate nutrition with a consistent reduction in stoma width. Guard cell length was higher in EC treatment as compared to AC. The guard cell width was maximum in AN-grown plants at EC. Epidermal cell density and stomatal density were lower at EC. Nitrate nutrition increased the stomatal area at EC while the reverse was true for MN and AN. Wheat plants fertilized with AN showed a higher accumulation of superoxide radical (SOR) at EC, while in NN treatment, the accumulation of hydrogen peroxide (H2O2) was higher at EC. Reactive oxygen species, particularly H2O2, can trigger mitogen-activated protein kinase (MAPK) mediated signaling and its crosstalk with abscisic acid (ABA) signaling to regulate stomatal anatomy in nitrate-fed plants. The SOR accumulation in ammonium- and ammonium nitrate-fed plants and H2O2 in NN-fed plants might finely regulate the sensitivity of stomata to alter water/nutrient use efficiency and productivity under EC. The data reveals that the variation in anatomical attributes viz. cell length, number of cells, etc. affected the leaf growth responses to EC and forms of N nutrition. These attributes are fine targets for effective manipulation of growth responses to EC.

Understanding the reproductive stage salinity stress tolerance is a key target for breeding stress tolerant rice genotypes. Nitrate and ammonium are equally important nitrogen forms utilized by rice. We evaluated nitrate and ammonium assimilation during reproductive stage in control and salinity (10dSm-1 using NaCl) stressed rice plants. Osmotic stress tolerant rice genotype Shabhagidhan (SD) and high yielding yet osmotic and salinity stress sensitive genotype Pusa sugandh-5 (PS5) were evaluated. Salinity stress was given to plants during panicle emergence and flag leaves was collected after 1d, 3d 5d, 7d, 9d,12d and 15d after anthesis. Reproductive stage salinity stress resulted in decrease of membrane stability, relative water content and osmotic potential of rice plants. Reproductive stage salinity stress decreased the expression of nitrate reductase (OsNIA), nitrite reductase (OsNiR), Glutamine synthetase (OsGLN1.1, OsGLN1.2, OsGLN2) and glutamate synthase/GOGAT (OsFd-GOGAT, OsNADH-GOGAT) in flag leaves. In response to stress, SD showed better stress tolerance than PS5 in terms of higher yield stability. Variety SD showed higher leaf nitrate and ammonium content and maintained comparatively higher nitrate and ammonia metabolism enzyme activity than PS5. Salinity stress upregulated the activity of glutamate dehydrogenase enzyme and indirectly contributed to the higher proline content and maintenance of favourable osmotic potential in SD. Expression of GS2 which has role in photo respiratory ammonia assimilation was upregulated by salinity stress in PS5 in comparison to SD. Rice genotype showing better induction of nitrogen assimilatory genes will be more tolerant to reproductive stage salinity stress.

Global food security, both in terms of quantity and quality remains as a challenge with the increasing population. In parallel, micronutrient deficiency in the human diet leads to malnutrition and several health-related problems collectively known as “hidden hunger” more prominent in developing countries around the globe. Biofortification is a potential tool to fortify grain legumes with micronutrients to mitigate the food and nutritional security of the ever-increasing population. Anti-nutritional factors like phytates, raffinose (RFO’s), oxalates, tannin, etc. have adverse effects on human health upon consumption. Reduction of the anti-nutritional factors or preventing their accumulation offers opportunity for enhancing the intake of legumes in diet besides increasing the bioavailability of micronutrients. Integrated breeding methods are routinely being used to exploit the available genetic variability for micronutrients through modern “omic” technologies such as genomics, transcriptomics, ionomics, and metabolomics for developing biofortified grain legumes. Molecular mechanism of Fe/Zn uptake, phytate, and raffinose family oligosaccharides (RFOs) biosynthesis pathways have been elucidated. Transgenic, microRNAs and genome editing tools hold great promise for designing nutrient-dense and anti-nutrient-free grain legumes. In this review, we present the recent efforts toward manipulation of genes/QTLs regulating biofortification and Anti-nutrient accumulation in legumes using genetics-, genomics-, microRNA-, and genome editing-based approaches. We also discuss the success stories in legumes enrichment and recent advances in development of low Anti-nutrient lines. We hope that these emerging tools and techniques will expedite the efforts to develop micronutrient dense legume crop varieties devoid of Anti-nutritional factors that will serve to address the challenges like malnutrition and hidden hunger.

Sugar beet is a salt-tolerant crop that can be explored for crop production in degraded saline soils. Seeds of multigerm genotypes LKC-2006 (susceptible) and LKC-HB (tolerant) were grown in 150 mM NaCl, from germination to 60 days after sowing, to decipher the mechanism of salinity tolerance at the vegetative stage. The biomass of the root and leaf were maintained in the tolerant genotype, LKC-HB, under saline conditions. Na+ /K+ ratios were similar in roots and leaves of LKC-HB, with lower values under salinity compared to LKC 2006. Infrared temperatures were 0.96°C lower in LKC-HB than in LKC-2006, which helped regulate the leaf water status under stressed conditions. Pulse-chase experiment showed that 14 C photosynthate was preferentially allocated towards the development of new leaves in the tolerant genotype. The sugar profile of leaves and roots showed accumulation of raffinose in leaves of LKC-HB, indicating a plausible role in imparting salinity tolerance by serving as an osmolyte or scavenger. The molecular analysis of the genes responsible for raffinose synthesis revealed an 18-fold increase in the expression of BvRS2 in the tolerant genotype, suggesting its involvement in raffinose synthesis. Our study accentuated that raffinose accumulation in leaves is vital for inducing salinity tolerance and maintenance of shoot dry weight in sugar beet.

Tissue and canopy-level evidence suggests that elevated carbon dioxide (EC) inhibits shoot nitrate assimilation in plants and thereby affects nitrogen (N) and protein content of the economic produce. It is speculated that species or genotypes relying more on root nitrate assimilation can adapt better under EC due to the improved/steady supply of reductants required for nitrate assimilation. A study was conducted to examine the effect of EC on N assimilation and associated gene expression in wheat seedlings. Wheat genotypes, BT-Schomburgk (BTS) with comparatively high leaf nitrate reductase (NR) activity and Gluyas Early (GE) with high root NR activity were grown in hydroponic culture for 30 days with two different nitrate levels (0.05 mM and 5 mM) in the climate controlled growth chambers maintained at either ambient (400 ± 10 μmol mol−1) or EC (700 ± 10 μmol mol−1) conditions. Exposure to EC downregulated the activity of enzyme NR and glutamate synthase (GOGAT) in leaf tissues, whereas in roots, activities of both the enzymes were upregulated by exposure to EC. In addition, EC downregulated N assimilation and signalling gene expression under high N availability. Root N assimilation was less affected in comparison with shoot N assimilation; thereby, the proportion of root contribution towards total assimilation was higher. The results suggest that EC could alter and re-programme N assimilation and signalling in wheat seedlings. The genotype and tissue-specific effects of EC on N assimilation also warrants the need for identification of suitable genotypes and revision of fertiliser regime for tapping the beneficial effects of EC conditions.

In drought prone areas, often farmers use less nitrogen, and thus the crop is subjected to combined stress (low N + osmotic stress). Since understanding the regulation of genes involved in nitrate signalling, uptake and assimilation under water-deficit (osmotic stress) is important for improving yield under the combined stress environments, this study analysed the regulation of genes coding for N responses under low N, osmotic stress (OS) and combined stress conditions in seedlings of a wheat. The results revealed that HD2967, a mega wheat variety, was more tolerant to short-term N starvation, OS and combined stress as compared with C306, a drought tolerant check. Interestingly, it was found that low N stress can also lead to accumulation of ABA in wheat seedlings. Real-time RT-qPCR analysis revealed that in addition to low N stress, OS also regulated expression of nitrate signalling genes (TaCIPK8, TaCIPK23, TaNLP4, TaSPL9, TabHLH1 and TaNAC4), HATS gene TaNRT2.1, LATS genes (TaNRT6.5 and TaNPF7.1), nitrate and nitrite assimilation genes and ammonium assimilation genes at least in one tissue of one of the genotypes. Combined stress was found to have significant interaction in regulation genes for nitrate signalling, uptake and assimilation. TabZIP1 and TaPIMP1 TF were identified as new players in low N response in wheat. Thus, osmotic stress and combined stress modulates the genes for N responses, and genotypic variation exists for this in wheat. The common expression pattern of N response genes found under low N and OS may probably regulated, at least in part, by ABA-dependent pathway, as ABA accumulation was induced by both OS and low N stresses. Functional analysis of the osmotic stress regulated genes coding for N response will help enhance tolerance of wheat to combined stress conditions.

In plants, reactive oxygen species accumulate to a toxic level under various abiotic stresses. Many antioxidant defense systems require NADPH as a principal reducing energy equivalent. However, the source of NADPH and the molecular mechanisms associated with the maintenance of cytoplasmic redox balance are still unknown. The present study describes Vigna NADH kinase (VlNADHK), an enzyme involved in NADPH synthesis and prefers NADH as a diphospho-nicotinamide nucleotide donor. We analyzed the enzymatic activity of a putative cytoplasmic NADH kinase during waterlogging in contrasting mung bean genotypes Vigna luteola (tolerant) and Vigna radiata cv. T44 (susceptible) under pot-culture condition. The tolerant cultivar showed higher enzymatic activity under waterlogging as well as after recovery. Similarly, the transcript level of waterlogging-induced NADHK expression was also studied and found to be upregulated in response to waterlogging in the roots of V. luteola and T44. PCR amplicons of partial and full-length sequences were cloned and sequenced from V. luteola. To the best of our knowledge, this is the first time an ATP-dependent NADH kinase gene has been recognized as a component of waterlogging stress tolerance in legumes. Our study indicated that this cytoplasmic NADH kinase is a primary source of the cytosolic NADPH and might have a role in waterlogging tolerance in legumes.

The reversible protein phosphorylation and dephosphorylation mediated by protein kinases and phosphatases regulate different biological processes and their response to environmental cues, including nitrogen (N) availability. Nitrate assimilation is under the strict control of phosphorylation—dephosphorylation mediated post-translational regulation. The protein phosphatase family with approximately 150 members in Arabidopsis and around 130 members in rice is a promising player in N uptake and assimilation pathways. Protein phosphatase 2A (PP2A) enhances the activation of nitrate reductase (NR) by deactivating SnRK1 and reduces the binding of inhibitory 14–3–3 proteins on NR. The functioning of nitrate transporter NPF6.3 is regulated by phosphorylation of CBL9 (Calcineurin B like protein 9) and CIPK23 (CBL interacting protein kinase 23) module. Phosphorylation by CIPK23 inhibits the activity of NPF6.3, whereas protein phosphatases (PP2C) enhance the NPF6.3-dependent nitrate sensing. PP2Cs and CIPK23 also regulate ammonium transporters (AMTs). Under either moderate ammonium supply or high N demand, CIPK23 is bound and inactivated by PP2Cs. Ammonium uptake is mediated by nonphosphorylated and active AMT1s. Whereas, under high ammonium availability, CIPK23 gets activated and phosphorylate AMT1;1 and AMT1;2 rendering them inactive. Recent reports suggest the critical role of protein phosphatases in regulating N use efficiency (NUE). In rice, PP2C9 regulates NUE by improving N uptake and assimilation. Comparative leaf proteome of wild type and PP2C9 over-expressing transgenic rice lines showed 30 differentially expressed proteins under low N level. These proteins are involved in photosynthesis, N metabolism, signalling, and defence.

Wheat is an important staple food crop of the world and it accounts for 18–20% of human dietary protein. Recent reports suggest that CO2 elevation (CE) reduces grain protein and micronutrient content. In our earlier study, it was found that the enhanced production of nitric oxide (NO) and the concomitant decrease in transcript abundance as well as activity of nitrate reductase (NR) and high affinity nitrate transporters (HATS) resulted in CE-mediated decrease in N metabolites in wheat seedlings. In the current study, two bread wheat genotypes Gluyas Early and B.T. Schomburgk differing in nitrate uptake and assimilation properties were evaluated for their response to CE. To understand the impact of low (LN), optimal (ON) and high (HN) nitrogen supply on plant growth, phenology, N and C metabolism, ROS and RNS signaling and yield, plants were evaluated under short term (hydroponics experiment) and long term (pot experiment) CE. CE improved growth, altered N assimilation, C/N ratio, N use efficiency (NUE) in B.T. Schomburgk. In general, CE decreased shoot N concentration and grain protein concentration in wheat irrespective of N supply. CE accelerated phenology and resulted in early flowering of both the wheat genotypes. Plants grown under CE showed higher levels of nitrosothiol and ROS, mainly under optimal and high nitrogen supply. Photorespiratory ammonia assimilating genes were down regulated by CE, whereas, expression of nitrate transporter/NPF genes were differentially regulated between genotypes by CE under different N availability. The response to CE was dependent on N supply as well as genotype. Hence, N fertilizer recommendation needs to be revised based on these variables for improving plant responses to N fertilization under a future CE scenario.

Tyrosine phosphorylation constitutes up to 5% of the total phophoproteome. However, only limited studies are available on protein tyrosine kinases (PTKs) that catalyze protein tyrosine phosphorylation in plants. In this study, domain analysis of the 27 annotated PTK genes in rice genome led to the identification of 18 PTKs with tyrosine kinase domain. The kinase domain of rice PTKs shared high homology with that of dual specificity kinase BRASSINOSTEROID- INSENSITIVE 1 (BRI1) of Arabidopsis. In phylogenetic analysis, rice PTKs clustered with receptor-like cytoplasmic kinases-VII (RLCKs-VII) of Arabidopsis. mRNAseq analysis using Genevestigator revealed that rice PTKs except PTK9 and PTK16 express at moderate to high level in most tissues. PTK16 expression was highly abundant in panicle at flowering stage. mRNAseq data analysis led to the identification of drought, heat, salt, and submergence stress regulated PTK genes in rice. PTK14 was upregulated under all stresses. qRT-PCR analysis also showed that all PTKs except PTK10 were significantly upregulated in root under osmotic stress. Tissue specificity and abiotic stress mediated differential regulation of PTKs suggest their potential role in development and stress response of rice. The candidate dual specificity PTKs identified in this study paves way for molecular analysis of tyrosine phosphorylation in rice.

Wheat is a major staple food crop worldwide contributing approximately 20% of total protein consumed by mankind. The nitrogen and protein concentration of wheat crop and grain often decline as a result of exposure of the crop to elevated CO2 (EC). The changes in nitrogen (N) assimilation, root system architecture, and nitric oxide (NO)-mediated N signaling and expression of genes involved in N assimilation and high affinity nitrate uptake were examined in response to different nitrate levels and EC in wheat. Activity of enzyme nitrate reductase (NRA) was downregulated under EC both in leaf and root tissues. Plants grown under EC displayed enhanced production of NO and more so when nitrate supply was high. Based on exogenous supply of NO, inhibitors of NO production, and NO scavenger, regulatory role of NO on EC mediated changes in root morphology and NRA was revealed. The enhanced NO production under EC and high N levels negatively regulated the transcript abundance of NR and high affinity nitrate transporters (HATS).

The rate of nitrate uptake was studied in ambient (AC) and elevated (EC, 600 ± 50 μmol mol−1) carbon dioxide conditions in wheat seedlings adapted to low nitrogen (uninduced) or high nitrogen (induced) conditions. Twenty five days old seedlings grown in climate controlled growth chambers were incubated in a range of nitrate concentrations (0.01–1 mM). Rate of uptake observed in low N adapted seedlings was used to calculate kinetics of constitutive high affinity transport system (CHATS). The difference in uptake observed between induced and uninduced seedlings were indicative of inducible high affinity transport system (IHATS). In both the CO2 levels, the nitrate uptake was biphasic in induced as well as uninduced seedlings, i.e. the rate of nitrate uptake saturated at about 0.08–0.1 mM and then a sharp increase in the rate of nitrate uptake was noticed in seedlings incubated in solutions of 0.5 mM nitrate and the uptake increased linearly in both induced as well as uninduced seedlings in the concentration beyond 0.5 mM. Hence, uninduced seedlings growing under EC took up nitrate more efficiently as compared to the seedlings growing under AC suggestive of efficient CHATS in EC grown plants. Growth under EC decreased both the affinity and rate of nitrate uptake in induced seedlings. However, the expression of TaNRT2.1, TaNRT2.2, TaNRT2.3 genes were highly induced by EC when the N supply level was low. Recent evidences suggest the involvement of ECO2-triggred synthesis of nitric oxide (NO) as a mediator of high affinity nitrate transporter activity in plants. The observed negative impact of EC on IHATS might also be an after effect of NO perturbation. EC could modify the inorganic nitrogen uptake by altering the access to or accessibility of nutrients in soil or by altering the kinetics of CHATS.

Drought is a major yield-limiting factor for rice production. Present study is a first of its own kind to show the promising role of plant growth regulators (PGRs) [methyl jasmonate (MJ), salicylic acid (SA), paclobutrazol (PBZ)] to mitigate drought induced notable variations in physio-biochemical parameters-relative water content (RWC), total antioxidant activity (TAO), total phenolic content (TPC), lipid peroxidation (LP), protein oxidation (PO), abscisic acid content (ABA) and NADPH oxidase (Nox) activity in contrasting rice genotypes-Nagina-22 (N-22, drought-tolerant) and Pusa Sugandh-5 (PS-5, drought-sensitive). It also revealed the changes in expressions of drought responsive genes (RD1, RD2) of AP2/ERF family and Nox family (Nox1, Nox5). A progressive increase in TPC (21–50 %), ABA content, (17–45 %), Nox (6–40 %), TAO (12–25 %) activity, while decrease in RWC (90−55 %), LP (64−25 %), PO (25−9 %) level, and expressions of RD1 and RD2 genes were found upregulated (∼1.4−1.8 fold) in primed samples under drought stress. Cloning, sequencing and characterization of Nox1 gene (accession number- MT771724) revealed its role in regulating oxidative burst during drought stress. Overall, seed-priming with MJ was identified to be highly effective to mitigate the deleterious effects of drought stress which could be further used to enhance drought tolerance in rice for improved yield under dry-land and rain-fed conditions.

The nitrogen (N) and protein concentration of wheat crop and grain often decline as a result of exposure of the crop to elevated CO2 (EC). In our earlier studies, it was found that the exacerbated production of nitric oxide (NO) represses the transcription of nitrate reductase (NR) and high affinity nitrate transporters (HATS) in EC grown wheat seedlings receiving high N. High N supply under EC also resulted in accumulation of reactive oxygen species (ROS), and reactive nitrogen species (RNS; NO and S- nitrosothiols) ensuing faster senescence and reduced N metabolite concentration in wheat. In this study, the effect of short-term exposure to EC on nitrate uptake kinetics was studied. The impact of EC on constitutive and inducible components of high affinity and low affinity nitrate uptake systems (HATS and LATS) were delineated in two wheat genotypes diverse in terms of nitrate uptake and assimilation capacities. Nitrate dose-response of NR was suppressed by EC in both leaf and root tissues. Plants grown under EC displayed a marked reduction in nitrate uptake kinetic components of LATS. Wheat genotype with high leaf nitrate assimilation capacity was able to maintain considerably higher nitrate uptake rate under EC albeit at a lower rate in comparison to ambient CO2. Wheat leaves exposed to EC displayed a comparatively higher abundance of NO and showed incremental abundance depending on increase in nitrate supply. Exogenous NO supply significantly suppressed the nitrate uptake rate of EC grown plants. Hence, EC-induced production of NO downregulates LATS kinetics in a genotype and nitrate dose-dependent manner.

Transitory starch plays a vital role in maintenance respiration as its degradation products provide substrate for the night respiration. A study was conducted with two contrasting rice cultivars: Vandana (high night temperature susceptible) and Nagina 22 (high night temperature tolerant) by subjecting them to increase in transition temperature from anthesis to physiological maturity. Night respiration on plant area basis increased by 35% in Vandana at 5 days after anthesis but was unaffected in tolerant cultivar. A simultaneous 18% decrease in starch content was observed in the susceptible cultivar. An analysis of the starch-metabolizing enzymes showed that activity of β-amylase increased markedly in Vandana whereas both β and α-amylase decreased in Nagina 22 following high day to night transition temperature exposure. The level of starch breakdown product, maltose, increased in the susceptible cultivar but glucose levels declined in both the cultivars. Concurrently, expression of chloroplastic isoforms α-amylase OsAMY1, OsAMY2 and β-amylase OsBAM2 increased in Vandana. A lower accumulation of dry matter was recorded in the susceptible than the tolerant cultivar. Our study elucidated the regulatory role of transitory starch in supporting the high day to night transition temperature-induced night-time respiration which is mediated by the increased activity of β-amylase through enhanced expression of OsBAM2 in flag leaves of susceptible cultivar.

Salt overly sensitive (SOS) pathway genes, SOS1 (plasma membrane Na+/H+ antiporter), SOS2 (CBL interacting protein kinase 24), and SOS3 (calcineurin B like protein 4) are associated with active efflux of toxic sodium ions (Na+) from cytosol and thus confer salinity tolerance in glycophytic plants such as Arabidopsis. The role of SOS pathway genes SOS2 and SOS3 in salinity tolerance of wheat is rarely studied. One-month-old seedlings of three bread wheat genotypes namely, HD 2009, HD2687 and Kharchia 65 were imposed with two levels of salinity stress (100 and 200 mM NaCl) for 30 days duration. Based on the physiological parameters, genotype Kharchia 65 was highly tolerant, HD 2009 was moderately tolerant and HD 2687 was sensitive to salinity stress. Tolerant genotypes accumulated lesser amount of Na+ in root, stem and leaf tissues. Transcript abundance of SOS1, SOS2 and SOS3 genes was significantly higher in salt tolerant genotypes under long-term salinity and correlated with improved sodium exclusion, and higher potassium/sodium (K+/Na+) ratio. Expression levels of genes involved in vacuolar partitioning of Na+, NHX1 (vacuolar Na+/H+ antiporter) and VP1 (Vacuolar pyrophosphatase) were also higher in salt tolerant wheat genotypes under 200 mM NaCl stress. Partial coding sequences of SOS1, SOS2, SOS3, NHX1 and VP1 genes were cloned and sequenced from the above mentioned three wheat genotypes. The results in the present study demonstrated that SOS pathway of ion homeostasis under salinity stress is conserved across species.