Investigating the Role of Phenolics and Antioxidative Defense Machinery of Brassica juncea (Indian mustard) During Progressive Infection of Alteraria blight

Abstract

Seven genotypes of Indian mustard (Brassica juncea) collected for quantitative phenolic assay and in vitro antioxidant activity during infection of Alternaria brassicae. Phenols, o-dihydroxy phenols and flavonols content were higher in resistant varieties than susceptible. Total phenol and o-dihydroxy phenolic contents increased while flavonol content decreased with disease progression. Antioxidant activities including reducing power, 2,2’-diphenyl-1-picrylhydrazyl radical scavenging, chelating activity on Fe⁺², revealed the increment in ROS level during infection but suddenly fall down in late infected stage. The antioxidant level found quite high in resistant variety while low in susceptible. The increasing antioxidant activity supports the hypothesis that there is a fine regulation of antioxidative system which is the part of signaling pathways activating defense responses.

Key words:

• Phenolic assay
• Antioxidative activity
• Brasica juncea
• Alternaria blight