Biochemical responses of soil-borne necrotroph Sclerotium rolfsii during the pathogenesis on chickpea

Southern blight caused by Sclerotium rolfsii is a fast spreading and destructive disease of chickpea yield. This disease cause severe damage to plant on almost all growth stage. In our study we have selected two genotype of chickpea i.e one is resistant genotype (GNG1958) and another susceptible genotype (L550) and two isolates of S. rolfsii i.e., highly aggressive (C4) and least aggressive (L9). Both isolates were inoculated on both genotypes and observation of enzymatic activity was done. Peroxidase activity was highest in case of susceptible genotype inoculated with least aggressive isolate. There was depletion in catalase and ascorbate peroxidase activity and enhancement in activity of peroxidase whether it was inoculated with highly or least aggressive isolate, but there was variation in superoxide dismutase activity. The enhanced biochemical activities during plant pathogen interaction triggers the defense related enzymes such as wall-bound phenolics, flavonoids and induction of hypersensitive reaction (HR) etc., which resulted in cell strengthening and enhances resistance to pathogen. The depletion of catalase and ascorbate peroxidase during host-parasite interaction might be due to induction of antioxidant enzyme in plant which leads to oxidative stress and multiplication of pathogen. In case of superoxide dismutase activity when resistant genotype inoculated with least aggressive isolate there was increase in activity but when susceptible genotype inoculated with least aggressive isolate there was decline in superoxide dismutase activity. Which shows superoxide dismutase activity could improve superoxide scavenging system of cells and favor accumulation of superoxide which mainly contributes in damaging the concentration and damage to cell membrane.