Induction of peroxidases and superoxide dismutases in transformed embryogenic calli of alfalfa ( Medicago sativa L.)

Peroxidase (POD) and superoxide dismutase (SOD) enzyme activities were analyzed in non-regenerative transformed embryogenic lines of alfalfa ( Medicago sativa L.) carrying wound-inducible oryzacystatin I ( OC-I), wound-inducible oryzacystatin I antisense ( OC-Ias), or hygromycin phosphotransferase ( hpt) genes. All of the transformed lines analyzed had elevated levels of all POD isoforms. Three POD isoforms with p I values of approximately 4.5, 4.8, and 8.4, and one additional pair of isoforms with a p I value of approximately 8.8 were separated from tissue extracts of all transgenic lines. Isoelectrofocusing patterns revealed the induction of one isoform of SOD with a p I of about 5.6 in all transgenic lines compared with non-transformed embryogenic tissue. These results indicate that the process of transformation may disrupt redox homeostasis in alflalfa tissues.