Over-expression of TaEXPB23, a wheat expansin gene, improves oxidative stress tolerance in transgenic tobacco plants.

Expansins are cell wall proteins inducing cell wall loosening and participate in all plant growth and development processes which are associated with cell wall modifications. Here, TaEXPB23, a wheat expansin gene, was investigated and the tolerance to oxidative stress was strongly enhanced in over-expression tobacco plants. Our results revealed that over-expressing TaEXPB23 influenced the activity of antioxidant enzymes: in particular, the activity of the cell wall-bound peroxidase. The enhanced tolerance to oxidative stress and increased cell wall-bound peroxidase activity were partly inhibited by an anti-expansin antibody. The Arabidopsis expansin mutant atexpb2 showed reduced cell wall-bound peroxidase activity and decreased oxidative stress tolerance. In addition, atexpb2 exhibited lower chlorophyll contents and the germination rate compared to wild type (WT). Taken together, these results provided a new insight on the role of expansin proteins in plant stress tolerance by cell wall bound peroxidase.