Soil salinity constitutes one of the main causes for crop yield reduction. A significant part of the Ecuadorian highland soils are considered as high-salinity because of their pyroclastic nature, the effects of erosion and the poor use of irrigation water. The tree tomato (Solanum betaceum) grows all across the highlands and in many cases is subject to high-salinity stress. The objective of the present study was to determine the level of tolerance to sodium chloride (NaCl) for in vitro cultured tree tomato. Plants were obtained from seven or eight locations depending on the essay performed. Seed germination, plantlet development from simple-node culture and in vitro plant growth were evaluated, using different NaCl concentrations. For the seed germination assays, an average of 62% of germination was obtained in a concentration of 50mM NaCl for the seven locations evaluated, and an average of 57% germination in a concentration of 75mM. For plant growth from single node culture, seven locations were evaluated and growth was observed in concentrations of up to 100mM NaCl for plants from all locations except Quero. Finally, the analysis of salinity stress tolerance limits for plantlet growth showed different responses in individuals from eight sampling locations, where plantlets from Chaltura tolerated up to 175 mMNaCl. These results confirm a difference in salinity tolerance from individuals between locations. The highest tolerance level was observed in plants from Chaltura, while the lowest tolerance level was observed in plants from Quero. This information is basic for future transcriptome studies, where genes involved with salinity tolerance can be identify in this interesting Andean crop.
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