Determinación del nivel de tolerancia a salinidad en condiciones <em>in vitro</em> de plantas de tomate de árbol (<em>Solanum betaceum</em>) provenientes de distintas localidades de la Sierra ecuatoriana

Abstract

Determination of the level of tolerance to salinity in in vitro AbstractSoil 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 mM NaCl. 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.Keywords. Solanum betaceum, salinity stress, tolerance, in vitro culture. ResumenLa salinidad de los suelos constituye una de las causas más importantes para la disminución de la productividad en cultivos agrícolas. Gran parte de los suelos de la Sierra ecuatoriana son considerados salinos, tanto por su naturaleza piroclástica como por la erosión y el mal uso del agua de riego. El tomate de árbol (Solanum betaceum) crece en la región interandina y en muchos casos se ve sometido al estrés salino. El objetivo del presente estudio fue determinar el grado de tolerancia del tomate de árbol a cloruro de sodio (NaCl) en cultivo in vitro. Se utilizó plantas de tomate de árbol provenientes de siete u ocho localidades dependiendo del ensayo realizado. Se evaluó la germinación de semillas, el desarrollo de plántulas a partir de nudo simple y el crecimiento de plántulas cultivadas in vitro en diferentes concentraciones de NaCl. En los ensayos de germinación de semillas se obtuvo un promedio de 62 % de germinación para siete localidades analizadas en una concentración de 50mM de NaCl, y un promedio de 57 % en una concentración de 75mM. En cuanto al cultivo de tomate de árbol a partir de nudo simple, se evaluó plantas de siete localidades de las cuales todas, con exce...

Differential expression of genes in response to salinity stress in tree tomato (Solanum betaceum)

“…S. betaceum plants from different localities of the Ecuadorian highlands were evaluated in vitro for their tolerance to salinity stress (Jaramillo et al, 2014). From these assays, we found differences in salinity tolerance between plants originating from different locations of the country.…”

“…The greatest salinity tolerance was found for individuals coming from the locality of Chaltura, in the province of Imbabura. The lowest tolerance was found in plants coming from the locality of Quero, in the province of Tungurahua (Jaramillo et al, 2014). In these assays, salinity tolerance was measured as the percentage of plantlets that survived when exposed to different salt concentrations in vitro.…”

“…For the differential display analysis, samples of seedlings treated with 100mM NaCl were collected after different times of exposure to salinity stress: 3, 9, 12, 24, and 48 hours. The salt concentration (100 mM NaCl) used corresponds to the maximum salt concentration at which S. betaceum could grow in vitro in the assays described by Jaramillo et al (2014). Total RNA was isolated from leaf samples using Trizol Reagent (Invitrogen) following the instructions of the manufacturer.…”

“…Prospectively, Andean agricultural biodiversity harbors novel abiotic stress tolerance mechanisms useful for plant breeding. The Andean "tree tomato" (Solanum betaceum) is a promising species matching these characteristics (Jaramillo et al, 2014). S. betaceum is an exotic fruit crop endemic to Bolivia and northern Argentina, but principally cultivated in Colombia, Peru and Ecuador (Prohens & Nuez, 2000).…”

“…In addition to these qualities, the species appears resilient to high-salinity stress. S. betaceum is successfully cultivated on marginal soils with high pyroclastic contents (Feicán et al, 1999) and recent in-vitro studies demonstrate the plant's ability to sustain growth under high NaCl concentrations (Jaramillo et al, 2014). As salinity stress gains relevance in global agriculture (Golldack, 2014), S. betaceum represents an attractive resource to study genetic mechanisms underlying fruit crop adaptability to marginal soils.…”