Peroxidase and Poly-Phenol Oxidase in Brassica juncea Plants Infected with Macrophomina phaseolina (Tassai) Goid. and their Implication in Disease Resistance

Studies on the peroxidase and poly-phenol oxidase activity in relatively resistant and susceptible strains of Brassica juncea at sequential intervals after inoculation with different isolates of Macrophomina phaseolina revealed that, fungus infected tissues had relatively higher activities of these oxidative enzymes in comparison to healthy plants, and tissues inoculated with ‘Weakly Virulent’ isolates always exhibited higher activity in comparison to ‘Moderately’, ‘Highly’ and ‘MostHighly Virulent’ isolates. At the early stages of the infection on 6th day, resistant plants showed higher activities in comparison to their susceptible counterparts. Very low activity of these enzymes could be recorded in healthy plants. Findings of this, study indicate the possible involvement of these oxidative enzymes in the resistance of this disease.