Induction of defense response in Indian mustard against Alternaria blight through abiotic inducers

Soaking seed overnight and foliar spray with salicylic acid, indole acetic acid, metalaxyl, dipotassium hydrogen orthophosphate, hydrogen peroxide, calcium chloride and ferric chloride as inducers provided induced resistance in plant against Alternaria brassicae, resulting in a decline in the disease incidence after 10 days of pathogen inoculation. The minimum disease incidence (14%) was recorded from salicylic acid treated plants. Challenge inoculation with abiotic inducers sensitized the seedlings to produce increased level of soluble proteins. The maximum increase of soluble protein content (24.26 and 24.72 mg/g of fresh leaves) was found in salicylic acid treated plant at 5 and 10 days after pathogen inoculation. Similarly, phenol content was (24.26 and 24.72 mg/g of fresh leaves) also found to be maximum in salicylic acid treated plant at 5 and 10 days of inoculation. Protein profiling by SDS-PAGE revealed that foliar spray with salicylic acid induced the synthesis of new proteins; however, such new proteins were not recorded in control.