Biochemical Changes as Defense Response during Pathogenesis by Alternaria cyamopsidis (Rang. and Rao), its Toxin and Fungicide Treatment in Clusterbean [Cyamopsis tetragonoloba (Linn.) Taub.]

The blight of clusterbean caused by Alternaria cyamopsidis pathogen is responsible for inciting the production of toxin, therefore, characteristic symptoms are developed on the host by the toxins. Culture filtrate (crude toxin) was partially purified using ammonium sulphate precipitation method, which was further separated through Sephadex G-75 column and eluted with acetate buffer. The toxin as produced by Alternaria cyamopsidis and fungicides (Mancozeb and Copper oxychloride) treated guar leaves were analyzed for product of lipid Peroxidation Melondialdehyde (MDA) and activities of Superoxide dismutase (SOD), Ascorbate peroxidase (ASPO) and Catalase (CAT). An increased level of MDA and activities of SOD and ASPO after 3 days and 9 days of challenge inoculation, whereas, toxin treated guar leaves showed higher level of MDA and activities of SOD and ASPO. Our results show the presence first line of the defense response as seen by induction of higher levels of MDA and increased activities of SOD and ASPO after challenge inoculation with A. cyamopsidis whereas, fungicide treatment is found to keep this defense response at a slighting lower level.