Articles
DO NATURAL PLANT PHENOLS PLAY A ROLE IN ECOLOGY?
Article number
381_1
Pages
36 – 45
Language
Abstract
The biological properties of the naturally occurring plant phenolics, of which some 8000 are known, are briefly reviewed.
The importance of their localisation within the plant, their enzymic liberation in more toxic form from bound conjugates and their ready oxidation by phenolases or peroxidases is discussed.
The various theories of plant resistance to microbial infection are considered and the success of the phytoalexin hypothesis to explain how some plants such as the pea are able to resist infection is highlighted.
The role of phenolics in protecting plants from overgrazing is reviewed.
Although condensed tannins have been implicated in the resistance mechanisms of trees, it is apparent that simple phenols may be more important than tannins in protecting birch, poplar and willow from grazing by hare and moose.
The earlier idea that tannins reduce the nutritional value of plants through irreversible binding to plant protein now seems unlikely.
However, it is still true that tannins may be antinutritional through direct interference within the animal body of the digestive processes.
The importance of their localisation within the plant, their enzymic liberation in more toxic form from bound conjugates and their ready oxidation by phenolases or peroxidases is discussed.
The various theories of plant resistance to microbial infection are considered and the success of the phytoalexin hypothesis to explain how some plants such as the pea are able to resist infection is highlighted.
The role of phenolics in protecting plants from overgrazing is reviewed.
Although condensed tannins have been implicated in the resistance mechanisms of trees, it is apparent that simple phenols may be more important than tannins in protecting birch, poplar and willow from grazing by hare and moose.
The earlier idea that tannins reduce the nutritional value of plants through irreversible binding to plant protein now seems unlikely.
However, it is still true that tannins may be antinutritional through direct interference within the animal body of the digestive processes.
Authors
J. B. Harborne
Keywords
Disease resistance, phytoalexins, herbivore resistance, condensed tannins
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