Expression of phenolics and defence-related enzymes in relation to red root rot disease of tea plants

Abstract

Red root rot caused by Poria hypolateritia is a dreadful disease in tea plant due to sudden death of bushes. In response to fungal pathogen, variation in the defence-related enzymes was investigated. The infected tea root was undertaken to study about various defence-related and pathogen-related enzymes. The infected root, as a prime response to disease attack, was subjected to the analysis of phenolics, phenylalanine ammonia lyase, tyrosine ammonia lyase, peroxidase, polyphenol oxidase, catalase, chitinase, β-1,3-glucanase and protease were assayed. The results on assay of defence-related enzymes revealed that the activity was significantly higher in infected roots when compared with healthy roots. Phenolics were accumulated more in infected roots. The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis further confirmed the presence of induced pathogenesis-related proteins in the infected root tissues. The activity of all enzymes was increased up to threefold amount when compared with normal ones. The accumulation of defence enzymes in plants revealed the virulence of root pathogen in stimulating induced systemic resistance of tea plants and phytopathogenicity causing pathogenesis. This study exemplify to recognise underlying processes in causing infection and to identify the existence of host–pathogen relationship.

Keywords:

• catalase
• chitinase
• Poria hypolateritia
• phenylalanine ammonia lyase
• peroxidase
• polyphenol oxidase

Acknowledgements

The authors are thankful to the Principal and the Management, K.S. Rangasamy College of Educational Trust, Tiruchengode, for providing necessary facilities and constant encouragement to carry out this study. Moreover, the first author is grateful to Jawaharlal Nehru Memorial Fund, New Delhi, for awarding a Jawaharlal Nehru Doctoral Fellowship.