ABSTRACT

Trehalose accumulation has been correlated with tolerance to different stress conditions. Expression of the yeast trehalose-6-phosphate synthase gene (TPS1) in transgenic tobacco improves drought stress tolerance. Evidence from further analysis of these transgenic plants, under salt and oxidative stress, suggests that protective effects also extended to plant ion homeostasis and oxidative damage.

Constitutively expressing yeast TPS1 tobacco plants exhibited lower accumulation of toxic cations and improved salt tolerance compared to the wild type. Moreover, LiCl treatment produced leaf lesions, accumulation of phenolic compounds and transcription of pathogenesis related (PR) genes that were attenuated in transgenic tobacco plants.

We proved the effective hydroxyl radical scavenging activity of trehalose by the ability to complete in a hydroxyl radical generating and detecting system. Under oxidative stress conditions TPS1 transgenic plants, growing on methyl viologen (MV) or hydrogen peroxide (H₂O₂) oxidative medium, developed roots and true leaves while tobacco wild type plants bleached at the cotyledon stage.

This newest evidence of protection on alkali cation toxicity and against the oxidative damage caused by reactive oxygen species, mediated by synthesis of trehalose–6-phosphate, further suggests that carbohydrate alterations produced by trehalose biosynthesis be linked to the stress response. This emphasises the prominent role of sugar metabolism in the plant stress-responsive pathway.