Salares versus coastal ecotypes of quinoa: Salinity responses in Chilean landraces from contrasting habitats.

Quinoa (Chenopodium quinoa Willd.) is a highly salt-tolerant species subdivided into five ecotypes and exhibiting broad intra-specific differences in tolerance levels. In a greenhouse study, Chilean landraces belonging either to the salares (R49) or coastal lowlands (VI-1, Villarrica) ecotype with contrasting agro-ecological origins were investigated for their responses to high salinity. The effects of two levels of salinity, 100 (T1) and 300 (T2) mM NaCl, on plant growth and on some physiological parameters were measured. Leaf and root Na(+) accumulation differed among landraces. T2 reduced growth and seed yield in all landraces with maximum inhibition relative to controls in R49. Salinity negatively affected chlorophyll and total polyphenol content (TPC) in VI-1 and Villarrica but not R49. Germination on saline or control media of seeds harvested from plants treated or not with NaCl was sometimes different; the best performing landrace was R49 insofar as 45-65% of seeds germinated on 500 mM NaCl-containing medium. In all landraces, average seedling root length declined strongly with increasing NaCl concentration, but roots of R49 were significantly longer than those of VI-1 and Villarrica up to 300 mM NaCl. Salt caused increases in seed TPC relative to controls, but radical scavenging capacity was higher only in seeds from T2 plants of R49. Total SDS-extractable seed proteins were resolved into distinct bands (10-70 kDa) with some evident differences between landraces. Salt-induced changes in protein patterns were landrace-specific. The responses to salinity of the salares landrace are discussed in relation to its better adaptation to an extreme environment.