Overexpression of a specific P. vulgaris (PvGSTU2-2) isoenzyme improves dimethenamid tolerance of transgenic tobacco plants

Plant glutathione transferases (GSTs) have a major role in plant herbicide detoxification system. PvGSTU2-2 has been isolated from leaves of Phaseolus vulgaris plants. The enzyme catalyses the conjugation of glutathione with chloroacetamide herbicides alachlor and metalachlor. In order to study in planta the ability of PvGSTU2-2 to detoxify chloroacetamide herbicides, we developed transgenic tobacco plants overexpressing PvGSTU2-2. The introgression of the transgene in the plant genome was confirmed by RT-PCR and the expression of PvGSTU2-2 with q-RTPCR analysis. In addition, it was verified that the transgenes codes functional proteins by measuring GST enzyme activity towards NBD-CI in transgenic lines. Three PvGSTU2-2 overexpressing lines were assayed for their tolerance towards the herbicide dimethenamid (chloroacetamide). Under in vivo conditions, T0 lines exhibited increased tolerance at 0,5 and 1 mg/L dimethenamid, with significantly increased shoot and root elongation compared to wild type plants. These results confirm that overexpression of PvGSTU2-2 in tobacco provides a way of conferring selectivity and enhancing crop safety and production