Proteomic characterization of herbicide safener-induced proteins in the coleoptile of Triticum tauschii seedlings

Proteomic methods such as two-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry, as well as immunoblotting, were used to identify herbicide safener-induced proteins in the coleoptile of Triticum tauschii, a diploid wheat containing the D genome also found in the cultivated, hexaploid wheat Triticum aestivum. The herbicide safener fluxofenim dramatically increased protein abundance in the molecular weight (Mr) range of 24 to 30 kDa, as well as a few higher Mr proteins, in the coleoptile of T. tauschii seedlings. In total, twenty proteins were identified in this study. Eleven proteins were highly safener induced and only weakly expressed in the control; seven proteins were new safener induced proteins that were not detected in the control. Two other proteins were constitutively expressed in both the control and safener-treated coleoptiles. Among the eighteen inducible proteins, fifteen were glutathione S-transferase (GST) subunits that fall into three subclasses: eight proteins were from the tau subclass, six proteins were from the phi subclass, and one protein was from the lambda class. Another three safener inducible proteins showed homology to the aldo/keto reductase family and with proteins that have roles in glycolysis and the Krebs cycle. Two constitutively expressed proteins were identified, one having highest homology to the dehydroascorbate reductase subclass of GSTs and one with an ascorbate peroxidase. Immunoblot analyses, using two different antisera raised against the same GST protein but differing in their specificity, were used to further characterize the GST proteins expressed in response to safener treatment. Results from immunoblotting, combined with mass spectral analysis, showed that post-translational modification of GST proteins in control and safener-treated coleoptiles may occur.