Comparative physiological and biochemical mechanisms of salt tolerance in five contrasting highland quinoa cultivars

Abstract

Background: Chenopodium quinoa Willd., a halophytic crop, shows great variability among different genotypesin response to salt. To investigate the salinitytolerance mechanisms, five contrasting quinoa cultivars belonging to highland ecotype were compared for their seed germination (under 0, 100 and 400 mM NaCl) and seedling’s responses under five salinity levels (0, 100, 200, 300 and 400 mM NaCl). Results: Substantial variations were found in plant size (biomass) and overall salinity tolerance (plant biomass in salt treatment as % of control) among the different quinoa cultivars. Plant salinity tolerance was negatively associated with plant size, especially at lower salinity levels (<300 mM NaCl), but salt tolerance between seed germination and seedling growth is was not closely correlated. Except for shoot/root ratio, all measured plant traits responded to salt in a genotype-specific way. Salt stress resulted in decreased plant height, leaf area, root length, and root/shoot ratio in each cultivar. With increasing salinity levels, leaf superoxide dismutase (SOD) activity and lipid peroxidation generally increased, but catalase (CAT) and peroxidase (POD) activities showed non-linear patterns. Organic solutes (soluble sugar, proline and protein) accumulated in leaves, whereas inorganic ion (Na + and K + )increased but K + /Na + decreased in both leaves and roots. Across different salinity levels and cultivars, without close relationships with antioxidant enzyme activities (SOD, POD, or CAT), salinity tolerance was significantly negatively correlated with leaf organic solute and malondialdehyde contents in leaves and inorganic ion contents in leaves or roots ( not except for root K + content), but positively correlated with K + /Na + ratio in leaves or roots. Conclusion: Our results establish indicate ed that leaf osmoregulation, K + retention, Na + exclusion, and ion homeostasis are the main physiological mechanisms conferring salinity tolerance of these cultivars, rather than the regulations of leaf antioxidative ability.As an index of salinity tolerance, K + /Na + ratio in leaves or roots can be used for the selective breeding of highland quinoa cultivars.

Salicylic acid ameliorates salinity tolerance in maize by regulation of phytohormones and osmolytes

“…NaCl stress led to an increase in Na + and Na + /K + ratio but a decrease in Ca 2+ and K + uptake in the current study. Comparable results were confirmed with El-Katony et al (2019) in Zea mays L., Cai and Gao (2020) in Chenopodium quinoa (Willd.). According to Ahanger and Agarwal (2017), Na + and K + share identical physicochemical composition due to which competition occurs between both ions for their uptake.…”

“…Increased protein content was also reported in many plants, i.e., lettuce and maize (Ahmed et al 2019, Jain andVaishnav 2019). In addition, Cai and Gao (2020) concluded that exceptional expression of stress proteins is a major strategy in maintaining integrity, original configuration, and topology of cellular membrane components to preserve their normal functioning under salt stress. In this respect, Jain and Vaishnav (2019) reported a considerable negative relationship between total protein level, cell, and membrane stability.…”

“…Plants accumulate higher amounts of Na + , Cl − , SO 4 2-, and Ca 2+ ions under salt stress causing severe ion toxicity (Chakdar et al 2019). Besides, toxicity to a particular ion differs among various plant species (Cai and Gao 2020). Ion toxicity could alter the cytoplasmic metabolic processes and might cause injurious impacts on photosynthesis (Chakdar et al 2019).…”

Transcriptome analysis and differential gene expression profiling of two contrasting quinoa genotypes in response to salt stress

“…Due to the outstanding grain nutritional quality and strong tolerance to various abiotic stresses, the potential crop quinoa has attracted worldwide attention, and the Food and Agriculture Organization of the United nations has declared 2013 the International Year of the Quinoa [38]. Being domesticated as a staple food for aboriginal inhabitants of Andes since 7000 years ago, quinoa diversity can be classi ed into ve major ecotypes: salares, inter-Andean valleys, highlands, yungas and coastal lowlands [39], and the salares landraces are deemed to have the highest salinity tolerance [40]. Until now, more than 16,400 accessions of quinoa and its wild relatives have been conserved in 59 gene banks across 30 countries [41].…”

Behind the scene: Critical role of reactive oxygen species and reactive nitrogen species in salt stress tolerance

“…Osmotic stress or imbalance causes water deficit, reduction in leaf area and closing of stomatal. To overcome osmotic and ionic stress, plants have developed various biochemical mechanisms, for example osmotic tolerance, ion exclusion and tissue tolerance (Cai & Gao, 2020), as well as synthesis of compatible solutes, alterations in membrane properties, induction of antioxidant defence mechanisms and hormonal balance (Roy et al., 2014).…”