Maintenance of root water uptake contributes to salt-tolerance of a wild tomato species under salt stress

Under salt stress, the regulatory mechanism of root water uptake in tomato species with different salt-tolerance remains unclear. Here, we compared water uptake, aquaporin expression and oxidative damage in roots of wild tomato Solanum pimpinellifolium 'L03708MODIFIER LETTER PRIME and cultivated tomato Solanum lycopersicum 'M82MODIFIER LETTER PRIME under salt stress (150 mM NaCl) and H2O2-caused oxidative stress which is usually induced by salt stress. The results showed that the seedling growth was inhibited and root hydraulic conductance in 'M82MODIFIER LETTER PRIME was decreased under salt stress, whereas these were unchanged in 'L03708MODIFIER LETTER PRIME. Under salt stress, the PIP1 aquaporin abundance was decreased in 'M82MODIFIER LETTER PRIME but unchanged in 'L03708MODIFIER LETTER PRIME, and the PIP2 abundance was decreased in both species. The membrane damage and hydrogen peroxide accumulation were more severe in 'M82MODIFIER LETTER PRIME than 'L03708MODIFIER LETTER PRIME under salt stress. Exogenous H2O2 increased the membrane electrolyte leakage and decreased the root hydraulic conductance, with the changes being more profound in 'M82MODIFIER LETTER PRIME than 'L03708MODIFIER LETTER PRIME. The PIP1 abundance was increased in 'L03708MODIFIER LETTER PRIME but decreased in 'M82MODIFIER LETTER PRIME by H2O2 treatment. These results suggest that the maintenance of PIP1 abundance and antioxidant defense capability in the wild tomato species may contribute to its maintenance of root water uptake and thus salt-tolerance under salt stress.