Phytohormone profiling in NaCl-treated plants of the halophyte tomato wild relative Solanum chilense comparatively to the cultivated glycophyte Solanum lycopersicum

Salinity is a major environmental stress limiting tomato production in arid and semi-arid conditions due to irrigation. Although cultivated tomato is quite sensitive to salinity, 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 behaviour of the cultivated glycophyte Solanum lycopersicum with its wild-relative halophyte Solanum chilense will help to unravel the strategies of plant response to salt stress. A holistic approach was used to compare the hormonal profile of Solanum lycopersicum and Solanum chilense plants subjected to 125 mM NaCl for 7 days. Solanum chilense displayed a contrasting behaviour comparatively to Solanum lycopersicum, not only for plant growth, mineral nutrition, osmotic adjustment but also regarding phytohormonal profiling. Salinity improved plant growth in Solanum chilense. This species behaved as an includer species accumulating higher concentration of Na+ in the shoot than Solanum lycopersicum, which exhibited an excluder behaviour. Moreover, the capacity to use inorganic ions as osmotica improved salt resistance in Solanum chilense and phytohormones could be involved in this process. Most hormonal compounds were higher in Solanum chilense than in Solanum lycopersicum. Interestingly, salicylic acid, ethylene and cytokinins were positively correlated with osmotic potential in Solanum chilense under salinity while these hormones were negatively correlated with osmotic adjustment in Solanum lycopersicum. This study revealed that both species respond differently to salinity and that involvement of phytohormones in this resistance was species specific