Salinity-induced glutathione synthesis in Brassica napus.

The role of S-assimilation and the biosynthesis of cysteine and glutathione were studied during the response to salt stress of wild-type and salt-tolerant transgenic Brassica napus L. (canola) plants overexpressing a vacuolar Na+/H+ antiporter. A 3-fold increase in cysteine and glutathione content was observed in wild-type plants exposed to salt stress, but not in the transgenic plants. The induction of cysteine and glutathione synthesis during salt stress in the wild-type plants suggests a possible protective mechanism against salt-induced oxidative damage. On the other hand, the salt-tolerant transgenic plants did not show significant changes in either cysteine or glutathione content, confirming the role of vacuolar Na+ accumulation and ion homeostasis in salt tolerance.