Abstract
BackgroundChenopodium quinoa Willd., a halophytic crop, shows great variability among different genotypes in response to salt. To investigate the salinity tolerance 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).ResultsSubstantial 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 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 organic solute and malondialdehyde contents in leaves and inorganic ion contents in leaves or roots (except for root K+ content), but positively correlated with K+/Na+ ratio in leaves or roots.ConclusionOur results indicate 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.
Highlights
Chenopodium quinoa Willd., a halophytic crop, shows great variability among different genotypes in response to salt
It is well-known that salares landraces have the highest salinity tolerance, extent of salinity tolerance of the highland ecotype, growing at high altitudes around Titicaca Lake, has received less attention
Seed germination Compared with the control, seed germination did not significantly reduce for each quinoa cultivar in the low salt condition (100 mM NaCl)
Summary
Chenopodium quinoa Willd., a halophytic crop, shows great variability among different genotypes in response to salt. In order to tolerate soil salinization conditions, besides anatomical and morphological plasticity, plants have evolved multiple physiological mechanisms, e.g., osmotic adjustment, increased antioxidant response, accumulation or exclusion. Being cultivated in widely edapho-climatic conditions since about last 7000 years, the broad diversity has traditionally led to the classification of five quinoa ecotypes adapted to different native geographic environments: salares, highlands, inter-Andean valleys, yungas, and coastal lowlands [9]. Among them, it is well-known that salares landraces have the highest salinity tolerance, extent of salinity tolerance of the highland ecotype, growing at high altitudes around Titicaca Lake, has received less attention. In four lowland genotypes of quinoa, the expression of two sodium transporter genes (i.e. CqSOS1 and CqNHX1) was differentially induced at different tissues (shoots vs. roots), and between genotypes (more salt-tolerant vs. less salt-tolerant genotypes) [13], suggesting that plant salt tolerance may depend upon different mechanisms of ion (Na and/or K) uptake/exclusion, translocation and compartmentation
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call