Allelopathy, 2nd edition

Allelopathy, 2nd edition

252 Toxins and Plant Pathogenesis: by J. M. Daly and B. J. Deverall. Academic Press, Sydney, 1983: pp. x+181. $34.00. It has always been a surprise t...

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Toxins and Plant Pathogenesis: by J. M. Daly and B. J. Deverall. Academic Press, Sydney, 1983: pp. x+181. $34.00. It has always been a surprise to me that some phytopathogens need to produce toxins to annihilate their (quaintly called) hosts. This is often true for animal pathogens which have so many easy ways to penetrate into the internal milieu of their victims and hence need some active and spiky weapon when faced with the real defences. One would have thought, however, that once a phytopathogen had penetrated the host's initial and much more difficult epidermal walls, it would not need to bother to produce anything to finally bump the sufferer off. It is like giving strychnine to your victim after you have shot him (or her), I suppose, therefore, we should regard those organisms which elaborate such interesting and complex toxic

Allelopathy, 2nd edition: by E. L. Rice. Academic Press, Orlando, 1984: pp. xi+421.

$64.00. The second edition of this extremely useful book, devoted mainly to descriptions of the deleterious activity of chemicals emitted from one plant on the growth and development of another, is very much like the first, but much more comprehensive. However, in spite of an extensive chapter on the mechanism of action of allelopathic agents, no real conclusions are drawn at the biochemical/physiologial level as to the reasons why common chemicals, like hydroxy-cinnamic acids, which while apparently showing no effect on the host should influence the health of neighbours which also contain them. We also need to know more about the natural inhibitors of germination which allow weedy seeds to remain dormant until stimulated by the 'right' crop. And what about the other biochemical transformations and interactions which


molecules as either being pessimists or poor shots. Anyway, this short but interesting book will certainly give you chapter and verse on the subject of plant-killing toxins. While not pretending to be an exhaustive survey of the literature, it has the guts of the subject well displayed. We still may ask why the different races of Alternaria altemata produce so many variable toxins. While I suspect that the answer may lie in 'immune' like responses of the various casualties, I would be at a loss to know what the structure of the resulting toxins were without a volume such as this. So, to each his own. I recommend you read this book and see. For biochemical systematics and ecologists it shows a glorious range of biochemical (response) mechanisms. And, do not doubt, this is only the tip of the iceberg. Perhaps, one day even my questions may be answered.

take place in the soil: effected by bacteria, fungi, a host of fauna? The role of each one needs careful investigation. Fortunately, this book is a responsible and comprehensive guideline to the nature of all the problems involved and, while it provides no answers, is really a must for all those interested in biochemical ecology. After all, who can say whether the observed differences in isozyme patterns in different populations of a given species of plant are not caused in part by allosteric effects of allelochemics? And, let us also take heed that allelochemistry provides a neat demonstration that there is not an all or nothing response to aggressive chemical (or other) warfare between different organisms, but a slow loss of the ability of the victim to fight. Often, and I guess usually, the end result takes years. Animal and bacterial (plus protistal and fungal0 ecologists should take this fully into consideration in all the interactions which they study. It is of course just as important in evolution where, somehow, we tend to expect speciation to happen tomorrow instead of the day (or a million years) after.