Screening Of Salt Tolerance In Chilean Landraces Of Quinoa: Agronomical, Physiological And Nutritional Parameters

Quinoa (Chenopodium quinoa Willd.) is a facultative halophyte and some varieties are able to cope with salinity levels as high as those present in sea water. Due to its traditionally broad cultivation area (from the salt flats of the Andes at 3,800 m above sea level to the seacoast and from Colombia down to southern Chile), there is a very wide range of quinoa cultivars adapted to specific conditions displaying a broad genetic variability in stress tolerance. For this reason, quinoa offers a valuable source of germplasm for breeding new cultivars adapted to stressful environments in diverse geographical conditions and for identifying mechanisms potentially useful in breeding tolerant glycophytes. In Chile, the genetic distance between highland (altiplano) and coastal cultivars of quinoa has been assessed but their responses to salinity are less known. In the present work, the response to salt treatments (0, 100 and 300 mM NaCl) was investigated in one altiplano landrace, R49, and two coastal ones, VI-1 and VR (from central and southern Chile, respectively). Salt treatment caused a significant increase in Na+ concentrations in all plant organs; the Na+ concentration accumulated in leaves under 300 mM salt was highest in VI-1 and was ca. 1.5- to 3-fold higher in leaves and roots of plants grown under 300 mM NaCl than 100 mM NaCl. Growth was significantly inhibited by the lower salt concentration only in R49, whereas 300 mM NaCl reduced growth also in VI-1 and VR, albeit to a lower extent than in R49. The concentrations of photosynthetic pigments, total phenolics and flavonoids were differentially affected by salt in leaves of the three cultivars. Seed production at harvest was unaffected or even enhanced (VR) by 100 mM NaCl relative to controls, while with 300 mM it was reduced in R49 and VI-1 (ca. 80% and 40% inhibition, respectively) but was not affected in VR. The germinability of seeds collected from plants grown in the presence (100 or 300 mM) or absence (0 mM) of NaCl was tested on agar plates containing 0-500 mM NaCl. Results showed that the response varied between landraces with VR exhibiting the highest sensitivity (germination was inhibited even by 100 mM NaCl). Seed protein profiles (SDS-PAGE of total proteins and the amount of the 11S seed storage protein chenopodin) were compared among different cultivars not treated with salt and the effect of salt treatments on protein profile were checked in the frame of the single cultivar; this allow to compare the differences due to the genotype and also the plant response to the salt treatments