Site-directed genotype screening for elimination of antinutritional saponins in quinoa seeds identifies TSARL1 as a master controller of saponin biosynthesis selectively in seeds.

Climate change may result in a drier climate and increased salinization, threatening agricultural productivity worldwide. Quinoa (Chenopodium quinoa) produces highly nutritious seeds and tolerates abiotic stresses such as drought and high salinity, making it a promising future food source. However, the presence of antinutritional saponins in their seeds is an undesirable trait. We mapped genes controlling seed saponin content to a genomic region that includes TSARL1. We isolated desired genetic variation in this gene by producing a large mutant library of a commercial quinoa cultivar and screening the library for specific nucleotide substitutions using droplet digital PCR. We were able to rapidly isolate two independent tsarl1 mutants, which retained saponins in the leaves and roots for defence, but saponins were undetectable in the seed coat. We further could show that TSARL1 specifically controls seed saponin biosynthesis in the committed step after 2,3-oxidosqualene. Our work provides new important knowledge on the function of TSARL1 and represents a breakthrough for quinoa breeding.

Application of natural and synthetic growth promoters improves the productivity and quality of quinoa crop through enhanced photosynthetic and antioxidant activities.

Modern agriculture is primarily concerned with enhanced productivity of field crops linked with maximum resources use efficiency to feed the increasing population of the world. Exogenous application of biostimulants is considered a sustainable and ecofriendly approach to improve the growth and productivity of agronomic and horticultural field crops. The present study was carried out to explore the comparative growth enhancing potential of plant biostimulants (moringa leaf extract at 3% and sorghum water extract at 3%) and synthetic growth promoters (ascorbic acid at 500 µM and hydrogen peroxide at 100 µM) on growth, productivity and quality of quinoa crop (cultivar UAF-Q7) because it has gained significant popularity among agricultural scientists and farmers throughout the world due to its high nutritional profile. A field experiment was carried out at the Research Area of Directorate of Farms, University of Agriculture, Faisalabad, Pakistan during quinoa cultivation season of 2016-2017 and repeated during next year (2017-2018). All the foliar treatments enhanced the physiological, biochemical, quality, growth and yield attributes of quinoa as compared to control group. However, maximum improvement was observed in chlorophyll a and b contents, photosynthesis and respiration rates, and water use efficiency by moringa leaf extract (MLE) application. MLE application was also found more responsive regarding the improvement in activities of peroxidase, catalase, superoxide dismutase, phenolics and glycine betaine as compared to other treatments. Mineral elements i.e. K, Ca and N in root as well as in shoot were found the highest in response to MLE application. Similarly, growth (plant fresh and dry biomass, plant length and grain yield) and grain quality parameters (protein, K and Ca) were also significantly enhanced. Application of MLE was found to be a viable approach to improve the growth and quality of produce as compared to synthetic compounds.

Assessment of cadmium and lead tolerance potential of quinoa (Chenopodium quinoa Willd) and its implications for phytoremediation and human health.

Soil contamination with Cd and Pb is a worldwide problem which not only degrades the environment but also poses a serious threat for human and animal health. Phytoremediation of these contaminated soils using halophytic plants like quinoa presents an opportunity to clean the soils and use them for crop production. The current experiment was performed to evaluate the Cd and Pb tolerance potential of quinoa and subsequently its implications for human health. Three weeks old quinoa seedlings were exposed to Cd (30, 60 and 90 mg kg-1) and Pb (50, 100 and 150 mg kg-1) levels along with a control. The results revealed that plant height decreased at highest levels of soil Cd and Pb. Shoot, root and seed dry weight decreased with increasing levels of soil Cd and Pb. Tissue Cd and Pb concentrations increased with increasing levels of Cd and Pb in soil, the highest Cd was found in roots while the lowest in seeds. The highest Pb concentration was found in shoots at low Pb level, while in roots at high level of Pb. Increasing levels of Cd and Pb stimulated the activities of measured antioxidant enzymes and decreased membrane stability index. The health risk assessments of Cd and Pb revealed that hazard quotient was < 1 for both the metals. However, the results of total hazard quotient showed that value was < 1 for Pb and 1.19 for Cd showing potential carcinogenicity. This study demonstrates that quinoa has good phytoremediation potential for Cd and Pb however, the risk of Cd toxicity is challenging for human health.

Prospects for the accelerated improvement of the resilient crop quinoa.

Crops tolerant to drought and salt stress may be developed by two approaches. First, major crops may be improved by introducing genes from tolerant plants. For example, many major crops have wild relatives that are more tolerant to drought and high salinity than the cultivated crops, and, once deciphered, the underlying resilience mechanisms could be genetically manipulated to produce crops with improved tolerance. Secondly, some minor (orphan) crops cultivated in marginal areas are already drought and salt tolerant. Improving the agronomic performance of these crops may be an effective way to increase crop and food diversity, and an alternative to engineering tolerance in major crops. Quinoa (Chenopodium quinoa Willd.), a nutritious minor crop that tolerates drought and salinity better than most other crops, is an ideal candidate for both of these approaches. Although quinoa has yet to reach its potential as a fully domesticated crop, breeding efforts to improve the plant have been limited. Molecular and genetic techniques combined with traditional breeding are likely to change this picture. Here we analyse protein-coding sequences in the quinoa genome that are orthologous to domestication genes in established crops. Mutating only a limited number of such genes by targeted mutagenesis appears to be a promising route for accelerating the improvement of quinoa and generating a nutritious high-yielding crop that can meet the future demand for food production in a changing climate.

Burkholderia Phytofirmans PsJN Stimulate Growth and Yield of Quinoa under Salinity Stress.

One of the major challenges in agriculture is to ensure sufficient and healthy food availability for the increasing world population in near future. This requires maintaining sustainable cultivation of crop plants under varying environmental stresses. Among these stresses, salinity is the second most abundant threat worldwide after drought. One of the promising strategies to mitigate salinity stress is to cultivate halotolerant crops such as quinoa. Under high salinity, performance can be improved by plant growth promoting bacteria (PGPB). Among PGPB, endophytic bacteria are considered better in stimulating plant growth compared to rhizosphere bacteria because of their ability to colonize both in plant rhizosphere and plant interior. Therefore, in the current study, a pot experiment was conducted in a controlled greenhouse to investigate the effects of endophytic bacteria i.e., Burkholderia phytofirmans PsJN on improving growth, physiology and yield of quinoa under salinity stress. At six leaves stage, plants were irrigated with saline water having either 0 (control) or 400 mM NaCl. The results indicated that plants inoculated with PsJN mitigated the negative effects of salinity on quinoa resulting in increased shoot biomass, grain weight and grain yield by 12%, 18% and 41% respectively, over un-inoculated control. Moreover, inoculation with PsJN improved osmotic adjustment and ion homeostasis ability. In addition, leaves were also characterized for five key reactive oxygen species (ROS) scavenging enzyme in response to PsJN treatment. This showed higher activity of catalase (CAT) and dehydroascobate reductase (DHAR) in PsJN-treated plants. These findings suggest that inoculation of quinoa seeds with Burkholderia phytofirmans PsJN could be used for stimulating growth and yield of quinoa in highly salt-affected soils.

Defoliation timing for optimal leaf nutrition in dual-use amaranth production systems.

BACKGROUND: Amaranth leaves can provide important nutrients to small-scale farming families growing amaranth for seed. Amaranth is known to be tolerant to defoliation, but there is little guidance on when defoliation should be performed for optimal nutritional benefits. This series of experiments assessed tolerance to defoliation at different points throughout the vegetative stage of development, in addition to the nutritional benefits and flavor of amaranth leaves at each stage. RESULTS: Overall, timing of defoliation had no impact on seed yield or quality. Fifty percent defoliation at any point did not significantly reduce seed yield, whereas 100% defoliation throughout development reduced seed yield. The nutritional value of amaranth leaves differed substantially throughout development, with the highest concentrations of iron mid-way through vegetative development, and the highest levels of vitamin A, magnesium, and copper at the end of the vegetative development stage. Palatability was highest in young leaves, and decreased as plants aged. We also found that neither timing nor intensity of defoliation had an influence on branching, which can negatively influence ease of harvest. CONCLUSIONS: These results indicate that amaranth leaves are a nutritious food source that provides vital nutrients at different concentrations throughout development. Farmers who wish to harvest both leaves and seeds can harvest up to 50% of the leaves at any point during vegetative development or bud formation while maintaining seed yield. Leaf harvest timing can thus be tailored to nutritional needs, although palatability decreases with plant age. © 2020 Society of Chemical Industry.

Comparative physiological and biochemical evaluation of salt and nickel tolerance mechanisms in two contrasting tomato genotypes.

Plant tolerance against a combination of abiotic stresses is a complex phenomenon, which involves various mechanisms. Physiological and biochemical analyses of salinity (NaCl) and nickel (Ni) tolerance in two contrasting tomato genotypes were performed in a hydroponics experiment. The tomato genotypes selected were proved to be tolerant (Naqeeb) and sensitive (Nadir) to both salinity and Ni stress in our previous experiment. The tomato genotypes were exposed to combinations of NaCl (0, 75 and 150 mM) and Ni (0, 15, and 20 mg l-1 ) for 28 days. The results revealed that the tolerant and sensitive tomato genotypes showed similar response to NaCl and Ni stress; however, the level of response was significantly different in both genotypes. The tolerant tomato genotype showed less reduction in growth than the sensitive genotype against both NaCl and Ni stress. Root and shoot ionic analysis showed a decrease in Na and increase in K concentration by increasing Ni levels in the growth medium. Moreover, accumulation of Na and Ni in tissues showed a decrease in membrane stability index and an increase in malondialdehyde contents. The activity of superoxide dismutase, catalase, peroxidase and glutathione reductase under NaCl and Ni stress was significantly higher in the tolerant compared to the sensitive genotype. Enhanced activity of many antioxidant enzymes in Naqeeb under stress conditions is among the other mechanisms that enabled the genotype to better detoxify reactive oxygen species and therefore Naqeeb tolerated the stresses better than Nadir.

Assessing the Nutritional Value of Root and Tuber Crops from Bolivia and Peru.

: All over the world, there are species which may be considered as neglected or underutilized despite their nutritious properties. At present, such crops contribute to food security in isolated areas by providing energy and nutrients in a diversified diet. Such genetic heritage-improved by ancient cultures-is under threat of losing biodiversity as well as the traditional knowledge associated with their cultivation and usage. Among these species, the Andean root and tuber crops (ARTCs) constitute a valuable resource which should be preserved and popularized because of their food and functional properties. We studied three ARTC species (mashua, arracacha, and yacon) to provide data on their composition, essential for increasing their use globally. We compared their nutritional values with the values of more widely used crops. Important differences in nutrient composition among ARTC landraces were found. Mineral nutrients showed significant differences among species. Considerable variations in the contents of prebiotics like fructooligosaccharides or functional elements (antioxidants and glucosinolates) were found among species and intraspecific samples. Certainly, these species are important assets to complement human nutrition and to secure supply of functional elements for healthy diets.

Amaranth as a Dual-Use Crop for Leafy Greens and Seeds: Stable Responses to Leaf Harvest Across Genotypes and Environments.

Dual-use production systems that utilize the green leaves as well as seeds from amaranth are highly promising for small-scale farmers around the world. The leaves are an important source of nutrients for farming families, while seeds can provide income. Farmers who use amaranth as a dual-use crop are concerned about the impacts of defoliation on seed yield. This experiment tested defoliation at various intensities and frequencies (0, 25, 50, 75, and 100% defoliation, 1, 2, and 3 times) under controlled conditions as well as under Danish and Mexican field conditions. Defoliation tolerance was tested in a total of seven varieties, spanning the three primary grain amaranth species: A. cruentus, A. hypocondriacus, and A. caudatus. In all of the varieties and environments tested, we found that neither seed yield nor quality was impacted by a single defoliation event at intensities up to 50% leaf removal. We observed similar responses with two and three consecutive defoliations in which we removed 25% of all leaves. Greater frequency and intensity of defoliation resulted in reduced seed yield in some environments, while seed quality (protein content and 1000 KW) did not appear to be affected. Dual-use production systems should be promoted with small-scale farmers around the world as promising systems for improving local nutrition while maintaining profits from seed production. This paper provides baseline guidelines for farmers regarding optimal defoliation intensities and frequencies.

Correction: Polymorphisms at phase I-metabolizing enzyme and hormone receptor loci influence the response to anti-TNF therapy in rheumatoid arthritis patients.

The original version of this Article contained an error in the spelling of the author Ana Rodríguez-Ramos, which was incorrectly given as Ana Rodríguez Ramos. This has now been corrected in both the PDF and HTML versions of the Article.

Polymorphisms at phase I-metabolizing enzyme and hormone receptor loci influence the response to anti-TNF therapy in rheumatoid arthritis patients.

The aim of this case-control study was to evaluate whether 47 single-nucleotide polymorphisms (SNPs) in steroid hormone-related genes are associated with the risk of RA and anti-TNF drug response. We conducted a case-control study in 3 European populations including 2936 RA patients and 2197 healthy controls. Of those, a total of 1985 RA patients were treated with anti-TNF blockers. The association of potentially interesting markers in the discovery population was validated through meta-analysis with data from DREAM and DANBIO registries. Although none of the selected variants had a relevant role in modulating RA risk, the meta-analysis of the linear regression data with those from the DREAM and DANBIO registries showed a significant correlation of the CYP3A4rs11773597 and CYP2C9rs1799853 variants with changes in DAS28 after the administration of anti-TNF drugs (P = 0.00074 and P = 0.006, respectively). An overall haplotype analysis also showed that the ESR2GGG haplotype significantly associated with a reduced chance of having poor response to anti-TNF drugs (P = 0.0009). Finally, a ROC curve analysis confirmed that a model built with eight steroid hormone-related variants significantly improved the ability to predict drug response compared with the reference model including demographic and clinical variables (AUC = 0.633 vs. AUC = 0.556; PLR_test = 1.52 × 10-6). These data together with those reporting that the CYP3A4 and ESR2 SNPs correlate with the expression of TRIM4 and ESR2 mRNAs in PBMCs (ranging from P = 1.98 × 10-6 to P = 2.0 × 10-35), and that the CYP2C9rs1799853 SNP modulates the efficiency of multiple drugs, suggest that steroid hormone-related genes may have a role in determining the response to anti-TNF drugs.KEY POINTS• Polymorphisms within the CYP3A4 and CYP2C9 loci correlate with changes in DAS28 after treatment with anti-TNF drugs.• A haplotype including eQTL SNPs within the ESR2 gene associates with better response to anti-TNF drugs.• A genetic model built with eight steroid hormone-related variants significantly improved the ability to predict drug response.

The effect of lactic acid bacteria inoculation, molasses, or wilting on the fermentation quality and nutritive value of amaranth (Amaranthus hypochondriaus) silage1.

This study assessed the influence of wilting, lactobacillus (LAB), and/or molasses on the chemical composition, phenolic compounds, in situ degradability, and in vitro ruminal fermentation parameters of amaranth (var. Maria) silage using a randomized complete block design with 6 replicates. Treatments were fresh amaranth forage (FAF), ensiled amaranth without additive (EA), EA inoculated with LAB (EAB), EA + 5% of molasses (EAM), EA inoculated with LAB + 5% of molasses (EABM), and 24-h wilted EA (WEA). The ensiled materials were stored anaerobically for a period of 45 d. Chemical composition, oxalic acid and nitrate levels, silage fermentation characteristics, DM disappearance (DMD), OM disappearance (OMD), in vitro ruminal ammonia-N, volatile fatty acids, cellulolytic bacteria and protozoa counts, and in situ DM and CP degradability were determined. Compared with FAF, EA had lesser values of water-soluble carbohydrates (P = 0.023), nitrate (P = 0.001), total phenolics (P = 0.04), total tannins (P = 0.01), DMD (P = 0.01), ruminal cellulolytic bacteria (P = 0.02), soluble and very rapidly degradable fraction (P = 0.014), and effective degradability (P = 0.01). The EA had lesser OMD and CP degradability compared with FAF (P < 0.05). Adding molasses to EA resulted in increased ash and lactate concentrations and decreased ammonia (P < 0.05), but had no effect on OMD. The WEA had lesser ammonia and greater lactate compared with EA (P < 0.05). Overall, fresh amaranth var. Maria can be preserved as a valuable silage to feed ruminants. Ensiling amaranth var. Maria decreased the antiquality compounds, and molasses addition improved the fermentation quality of the silage.

Combined effects of soil salinity and high temperature on photosynthesis and growth of quinoa plants (Chenopodium quinoa).

The halophytic crop quinoa (Chenopodium quinoa Willd.) is adapted to soil salinity and cold climate, but recent investigations have shown that quinoa can be grown in significantly warmer latitudes, i.e. the Mediterranean region, where high temperature and soil salinity can occur in combination. In this greenhouse study, effects of saltwater irrigation and high temperature on growth and development of the Bolivian cultivar 'Achachino' were determined. Development was slightly delayed in response to saltwater treatment, but significantly faster at high temperature. Biomass and seed yield decreased in response to salt, but not to high temperature. Plants increased their number of stomata in response to salt stress, but reduced its size on both sides of the leaf, whereas high temperature treatment significantly increased the stomata size on the abaxial leaf surface. When salt and high temperature was combined, the size of stomata was reduced only on the abaxial side of the leaf, and the number of epidermal bladder cells significantly increased on the abaxial leaf surface, resulting in preservation of photosynthetic quantum yields. We hypothesise that this morphological plasticity improves the partition of water and CO2 resulting in maintenance of photosynthesis in quinoa under adverse environmental conditions. We present a GLM-model that predicts yield parameters of quinoa grown in regions affected by soil salinity, high temperature and the factors combined.

The Global Expansion of Quinoa: Trends and Limits.

Quinoa (Chenopodium quinoa Willd.) was first domesticated in Andean countries over 7000 years ago. Following the Spanish conquest, quinoa was rejected as "Indian food." After centuries of neglect, the potential of quinoa was rediscovered during the second half of the 20th century. Since then, the number of countries importing quinoa increased, with new producers appearing on the map and quinoa now being cultivated in areas outside the Andean countries. The geographical increase in distribution of quinoa has highlighted the difficulty of access to quality seed, which is a key factor for testing the crop outside the Andes. In this context, research partnerships have helped promote the exchange of quinoa germplasm and have allowed trials to be undertaken in non-traditional areas of cultivation. The number of countries growing the crop has increased rapidly from eight in 1980, to 40 in 2010, and to 75 in 2014. A further 20 countries have sown quinoa for the first time in 2015. In this paper, we analyze this trend and discuss the limits of quinoa's expansion. As commercial production of quinoa is expected to develop, changes in international regulatory frameworks on genetic resources are needed in order to facilitate plant breeding for the most adaptive varieties for each region.

Enhancing salt tolerance in quinoa by halotolerant bacterial inoculation.

Quinoa is a facultative halophytic seed crop of increasing interest worldwide. Its performance declines under high salinity but can be improved by using halotolerant plant growth-promoting bacteria (PGPB) containing multi-traits, i.e. ACC-deaminase activity, exopolysaccharide secretion and auxin production. This study focussed on improving the productivity of quinoa through the use of six plant growth-promoting bacterial strains (both endophytic and rhizosphere). These were screened by conducting osmoadaptation assay, and the two most halotolerant strains (Enterobacter sp. (MN17) and Bacillus sp. (MN54)) were selected. These two strains were evaluated for their effects on growth, physiological characters and yield of quinoa. At the five leaf stage plants were irrigated with saline water having either 0 or 400mM NaCl. The results indicated that saline irrigation significantly decreased the growth of quinoa, whereas inoculation of plants with MN17 and MN54 mitigated the negative effects of salinity by improving plant water relations and decreasing Na+ uptake, which consequently, reduced osmotic and ionic stress. Strain MN54 performed better than MN17, which might be because of its better growth promoting traits and higher rhizosphere colonisation efficiency than MN17. Our results suggest that growth and productivity of quinoa could be improved by inoculating with highly tolerant PGPB strain in salt-affected soils.

Rutin, a flavonoid with antioxidant activity, improves plant salinity tolerance by regulating K+ retention and Na+ exclusion from leaf mesophyll in quinoa and broad beans.

The causal relationship between salinity and oxidative stress tolerance is well established, but specific downstream targets and the role of specific antioxidant compounds in controlling cellular ionic homeostasis remains elusive. In this work, we have compared antioxidant profiles of leaves of two quinoa genotypes contrasting in their salt tolerance, with the aim of understanding the role of enzymatic and non-enzymatic antioxidants in salinity stress tolerance. Only changes in superoxide dismutase activity were correlated with plant adaptive responses to salinity. Proline accumulation played no major role in either osmotic adjustment or in the tissue tolerance mechanism. Among other non-enzymatic antioxidants, rutin levels were increased by over 25 fold in quinoa leaves. Exogenous application of rutin to glycophyte bean leaves improved tissue tolerance and reduced detrimental effects of salinity on leaf photochemistry. Electrophysiological experiments revealed that these beneficial effects were attributed to improved potassium retention and increased rate of Na+ pumping from the cell. The lack of correlation between rutin-induced changes in K+ and H+ fluxes suggest that rutin accumulation in the cytosol scavenges hydroxyl radical formed in response to salinity treatment thus preventing K+ leak via one of ROS-activated K+ efflux pathways, rather than controlling K+ flux via voltage-gated K+-permeable channels.

Ionic and photosynthetic homeostasis in quinoa challenged by salinity and drought - mechanisms of tolerance.

Quinoa (Chenopodium quinoa Willd.) grown under field conditions was exposed to five irrigation water salinities (0, 10, 20, 30 and 40dSm-1; 4:1 NaCl:CaCl2 molar ratio) from flowering, and divided between full irrigation and progressive drought (PD) during seed filling. Quinoa demonstrated homeostatic mechanisms which contributed to quinoa's extraordinary tolerance. Salinity increased K+ and Na+ uptake by 60 and 100kgha-1, respectively, resulting in maintenance of cell turgor by osmotic adjustment, and a 50% increase of the leaf's fresh weight (FW):dry weight (DW) ratio and non-significant increase in elasticity enhanced crop water-capacitance. Day respiration (Rd) increased 2.7 times at high salinity but decreased 0.6 times during drought compared with control. Mesophyll conductance (gm) tended to be negatively affected by salinity as the increased succulence (FW:DW) possibly decreased intercellular space and increased cell-wall thickness. However, the increased K+ uptake seemed to alleviate biochemical limitations, as maximum Rubisco carboxylation rate (Vcmax) and photosynthetic electron transport (J) tended to increase under salinity. Overall, salinity and PD restricted stomatal conductance (gs) and photosynthesis (An) moderately, leading to decreased leaf internal to ambient [CO2], increase of intrinsic-water-use-efficiency (An/gs). The saturated electrical conductivity (ECe) resulting in 50% yield was estimated to be 25dSm-1, reaching no yield at 51.5dSm-1.

Differential activity of plasma and vacuolar membrane transporters contributes to genotypic differences in salinity tolerance in a Halophyte Species, Chenopodium quinoa.

Halophytes species can be used as a highly convenient model system to reveal key ionic and molecular mechanisms that confer salinity tolerance in plants. Earlier, we reported that quinoa (Chenopodium quinoa Willd.), a facultative C3 halophyte species, can efficiently control the activity of slow (SV) and fast (FV) tonoplast channels to match specific growth conditions by ensuring that most of accumulated Na+ is safely locked in the vacuole (Bonales-Alatorre et al. (2013) Plant Physiology). This work extends these finding by comparing the properties of tonoplast FV and SV channels in two quinoa genotypes contrasting in their salinity tolerance. The work is complemented by studies of the kinetics of net ion fluxes across the plasma membrane of quinoa leaf mesophyll tissue. Our results suggest that multiple mechanisms contribute towards genotypic differences in salinity tolerance in quinoa. These include: (i) a higher rate of Na+ exclusion from leaf mesophyll; (ii) maintenance of low cytosolic Na+ levels; (iii) better K+ retention in the leaf mesophyll; (iv) a high rate of H+ pumping, which increases the ability of mesophyll cells to restore their membrane potential; and (v) the ability to reduce the activity of SV and FV channels under saline conditions. These mechanisms appear to be highly orchestrated, thus enabling the remarkable overall salinity tolerance of quinoa species.

Genotypic difference in salinity tolerance in quinoa is determined by differential control of xylem Na(+) loading and stomatal density.

Quinoa is regarded as a highly salt tolerant halophyte crop, of great potential for cultivation on saline areas around the world. Fourteen quinoa genotypes of different geographical origin, differing in salinity tolerance, were grown under greenhouse conditions. Salinity treatment started on 10 day old seedlings. Six weeks after the treatment commenced, leaf sap Na and K content and osmolality, stomatal density, chlorophyll fluorescence characteristics, and xylem sap Na and K composition were measured. Responses to salinity differed greatly among the varieties. All cultivars had substantially increased K(+) concentrations in the leaf sap, but the most tolerant cultivars had lower xylem Na(+) content at the time of sampling. Most tolerant cultivars had lowest leaf sap osmolality. All varieties reduced stomata density when grown under saline conditions. All varieties clustered into two groups (includers and excluders) depending on their strategy of handling Na(+) under saline conditions. Under control (non-saline) conditions, a strong positive correlation was observed between salinity tolerance and plants ability to accumulate Na(+) in the shoot. Increased leaf sap K(+), controlled Na(+) loading to the xylem, and reduced stomata density are important physiological traits contributing to genotypic differences in salinity tolerance in quinoa, a halophyte species from Chenopodium family.