Improved salt tolerance of transgenic tobacco expressing apoplastic yeas-derived invertase

We investigated the salt tolerance of transgenic tobacco, in which yeast in vertase is expressed in the apoplastic (Apo-Inv) spaces. Whereas photosynth etic activities in wild-type tobacco in light were inhibited under salt str ess, transgenic Apo-Inv tobacco maintained constant photosynthetic activiti es. The physical appearance of plants under salt stress also indicates that yeast invertase expression in the apoplastic space is beneficial for induc ing salt tolerance. Apo-Inv tobacco had a much higher osmotic pressure incr ease in the cell sap than did wild-type tobacco under this type of stress. The physiological importance of sucrose metabolism under salt stress is dis cussed.