Characterisation of a novel soybean candidate glutathione peroxidase/thioredoxin-dependent peroxidase in soybean exposed to osmotic/drought stress

Abstract

Drought stress is a major contributor to reduced soybean crop yield and quality, this can however be mitigated by the plant’s antioxidant defence mechanisms. One group of antioxidant enzymes that are active in these defence mechanisms are glutathione peroxidases (GPXs). GPXs are antioxidant proteins which are able to reduce H2O2, a toxic reactive oxygen species which accumulates under stress conditions. This study aims at isolating the protein encoded by Glyma01g42840 and determining if it has Phospholipid hydroperoxidase glutathione peroxidase (PHGPX) and/or Thioredoxin dependent peroxidase (TRX-PX) activity as well as assaying the effect of Drought stress on the expression of this putative GPX . This will be accomplished by molecular cloning, sequencing as well as the expression of the isolated protein to assay it enzymatic activity. It was found that the enzyme encoded by Glyma01g42840 is able to use glutathione and thioredoxin as electron donors for the detoxification peroxides, however enzymatic activity is more efficient when using glutathione as an electron donor. In conclusion it was found that glyma01g42840 encodes an enzyme which is able to utilise more than one electron donor and as glutathione produces the greatest amount of enzymatic activity it can be said that glyma01g42840 encodes a GPX.