Probing the involvement of proteases and protease inhibitors during disease progression of Alternaria blight of Brassica

In the present investigation an effort was made to detect change in stechiometric balance of proteases and proteases inhibitors during Programmed cell death (PCD) at different stages of Alternaria blight infection in susceptible and tolerant cultivar of Brassica juncea. Protease and protease inhibitors were determined by in gel assay. Protease activity in tolerant was found to be higher than susceptible variety. High activity could trigger PCD to stop biotrophic growth of the Alternaria brassicae and help in protein processing to release elicitors which may take part in induced defense. In gel protease inhibitor assay showed that the cysteine protease inhibitor activity increased as the disease progresses in susceptible plant. After stage 4, it gradually decreased and became zero in stage 5 to 6. This reflects a change in stochiometric balance between cysteine proteases and protease inhibitors at various stages of infection to regulate PCD induced in response to pathogen attack.