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.

Keywords:

• Constitutive and induced resistance
• oxidative enzymes
• peroxidase and polyphenol oxidase
• phenolics
• phenylalanine ammonia lyase

Acknowledgements

The authors are thankful to the CGIAR Research Program on Grain Legumes and Dryland Cereals (GLDC), and Pearl Millet Hybrid Parents Research Consortium (PMHPRC) for the financial support. The authors also express their gratitude to Dr. Hari C. Sharma and Dr. Hari K. Sudini and their teams for access to their laboratory facilities which helped in carrying out the study.

Disclosure statement

The authors declare no conflict of interests.

Additional information

Funding

The work was funded by the CGIAR Research Program on Grain Legumes and Dryland Cereals (GLDC), and Pearl Millet Hybrid Parents Research Consortium (PMHPRC).