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ThèseEG2017.pdf
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- Abstract
- Tomato (Solanum lycopersicum) is one of the most important fruit vegetables in the economic sphere and its production could be limited by salinity in arid and semi-arid conditions due to irrigation. Salinity is now a major critical environmental stress limiting agriculture world-wide. Although cultivated tomato is quite sensitive to salt toxicity, several of its wild relatives exhibit halophyte properties. Solanum chilense is spontaneously present in salt-affected areas of North Chile but the physiological basis of its salt-resistance has received only minor attention so far. Comparing the behavior of the cultivated glycophyte S. lycopersicum with its wild-relative halophyte plant species S. chilense will help to unravel the strategies of plant response to salt stress. This study aimed to determine the effects of exogenous application of salicylic acid on the toxic effects of salt in relation to ethylene and polyamine synthesis in Solanum lycopersicum cv Ailsa Craig and S. chilense. Salinity decreased plant growth in S. lycopersicum without affecting endogenous ethylene, or polyamine concentrations. Exogenous application of salicylic acid alleviates salt stress in S. lycopersicum by interfering with ethylene and polyamine metabolism, thus promoting growth, delaying leaf senescence and contributing to ionic homeostasis. In S. chilense, NaCl improved plant growth and increased production of ethylene and spermine. The involvement of ethylene in the salt tolerance of S. chilense was further confirmed by treatment with an ethylene biosynthesis inhibitor, aminoethoxyvinylglycine (AVG). The decrease in ethylene production due to AVG was correlated with a reduction of salt tolerance in S. chilense in relation with a decrease of shoot growth, stomatal conductance and spermine concentration. We found also that the capacity to use inorganic ions as osmotica may improve salt resistance in S.chilense and that phytohormones could be involved in this process. To conclude, this study revealed that both species respond differently to salinity and that involvement of phytohormones in this resistance was species specific.
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