Salinity acclimation ameliorates salt stress in tomato (Solanum lycopersicum L.) seedlings by triggering a cascade of physiological processes in the leaves

•Pre-exposure to mild salt stress primes plants against subsequent severe salt stress.•Level of pre-treatment and cultivar type were critical factors for acclimation.•Acclimating plants accumulated lower concentration of Na+ in the leaves.•Acclimating plants also showed better ROS detoxification capacity and higher membrane integrity.