Expression of defense-related enzymes in blast [Magnaporthe grisea (Herbert) Barr] resistant and susceptible genotypes of pearl millet [Pennisetum glaucum (L.) R. Br.

Abstract

Fifteen genotypes of pearl millet were selected for biochemical characterization of blast resistance at plumule stage, and 4, 8, 12, 24, 48 and 72 hours post inoculation (hpi) with Magnaporthe grisea. The total phenol content, phenylalanine ammonia lyase (PAL), peroxidase (PO) and polyphenol oxidase (PPO) activity was observed to increase in M. grisea inoculated plants; however, a greater activity of these enzymes was found in resistant than susceptible genotypes at all the time intervals. The native-PAGE analysis of PO showed presence of five isoforms PO1 to PO5 but could not reveal any specific isoform to distinguish the resistant from susceptible genotypes. In the native-PAGE banding pattern of PPO, there were four isoforms PPO1 to PPO4 of which PPO3 was specific to three resistant genotypes at 4 hpi. Among the analyzed genotypes, IP 11036 showed highest total phenol content and PO activity, whereas IP 21187 exhibited highest PAL and PPO activities.