Peroxidase Activity and Hydrogen Peroxide Production in Vigna aconitifolia Leaves Infected with Macrophomina phaseolina

The ROS formation is associated with increased activity of enzymes participating in their metabolism with the induction of defense response in the host moth bean [Vigna aconitifolia (Jacq.) Marechal] plant against the fungal pathogen, Macrophomina phaseolina. Changes in peroxidase (EC 1.11.1.7) activity were determined in control and fungal pathogen inoculated plants of two varieties viz. RMO-40 and FMM-96. The peroxidase activity was higher in the pathogen inoculated plants as compared to control. Varietal differences were also observed as the peroxidase activity was comparatively higher in variety FMM-96, which is moderately resistant as compared to RMO-40 a susceptible variety. The presence of H₂O₂, which is involved in the oxidative cross-linking of cell wall glycoproteins was also detected histochemically in leaves of moth bean plants as reddish brown patches using 3,3-diaminobenzidine (DAB). The data indicate hydrogen peroxide production and a distinct role of peroxidase in the defense response of moth bean plants, an economically important crop of semi arid regions.