Physiological and hormonal responses underlying salinity tolerance in wild tomatoes: Insights for cultivated varieties

Soil salinisation is one of the main abiotic stress factors threatening modern agriculture, with over 1.3 million hectares affected worldwide and causing a progressive loss of arable land. Tomatoes are among the most important horticultural crops globally, but its moderate salt tolerance restricts productivity in saline soils. Related wild species, such as Solanum pimpinellifolium L., which have evolved in high-salinity environments, represent a valuable resource for studying adaptive stress responses and improving cultivated tomatoes. This study compares the salt stress response of S. lycopersicum L. and S. pimpinellifolium L. to identify the processes underlying the higher tolerance in wild species. Plants were grown hydroponically in a closed-loop system using two nutrient solutions: one mimicking seawater irrigation (33 % seawater, EC = 21 dS m −1 ), and a salt-free control (0 % seawater, EC = 3.22 dS m −1 ). Phenological, morphological, biochemical, physiological and hormonal traits were assessed. Solanum pimpinellifolium L. effectively modulates the production of osmolytes and photoprotective compounds, the translocation of toxic ions, and improves leaf function which, in synergy with a more integrated and temporally coordinated hormonal network that sustain better growth, yield, and fruit quality under saline conditions. These findings provide new insights into the physiological basis of salt tolerance in wild tomato, supporting its value as a genetic resource and suggesting that seawater-based irrigation may serve as a framework for studying sustainable water management strategies. • Wild tomato S. pimpinellifolium shows superior salt stress tolerance. • Coordinated hormonal networks underpins physiological and reproductive stability. • Closed-loop hydroponics with seawater offers a proof of concept for salinity research.