De novo synthesis of peroxidase isozymes of soybean var. clark-63 infected with the root-knot nematode, Meloidogyne incognita

Axenized second-stage larvae of Meloidogyne incognita were inoculated with a nine-day-old seedlings of soybean var. Clark-63. Assays of peroxidase activity was determined by polyacrylamide gel electrophoresis and treatment with an inhibitor, actinomycin-D (ACTD). The electrophoretic analyses revealed presence of additional bands of peroxidase isozymes that were separated 7, 14 and 21 days after inoculation. Addition of ACTD (1 μg/ml) caused an abrupt cessation of these additional bands. The possibility of rapid increase of new peroxidase activity resulting from pre-existing inactive form of enzyme was ruled out. It is suggested that the elevated level of peroxidase activity was due to de novo synthesis of peroxidase isozymes.