Induction and photoreversal of bean leaf peroxidase isoenzymes by germicidal and near ultraviolet radiation

The effects of germicidal u.v. and near-u.v. irradiation on bean leaf peroxidase activity were studied by means of isoelectric focusing techniques. The results indicated that peroxidase levels can be stimulated in detached leaves by an appropriate dose of germicidal u.v. The peroxidase stimulation due to germicidal u.v. irradiation could be partially reversed by a subsequent exposure to near-u.v. Near-u.v. alone at lower exposures failed to stimulate peroxidase activity. By isoelectric focusing of samples of leaf extracts it was determined that two peroxidase isoenzymes were induced by germicidal u.v. These two isoenzymes were absent in control leaves receiving no irradiation. The isoenzymes could be induced by germicidal u.v. and then reduced in activity by exposing the leaves to near-u.v. Among several peroxidase isoenzymes induced by the tumor producing bacterial pathogen, Agrobacterium tumefaciens, two were similar in isoelectric points to the two isoenzymes induced by germicidal u.v.