Trends in Plant Science
Research NewsThe raison d'être of secondary plant chemicals?
Section snippets
Evolution and ecology – adaptive functions
Louise Vet and Marcel Dicke (Wageningen University, The Netherlands) are among the principal proponents of the importance of plant volatiles in invertebrate carnivore (predator and parasitoid) foraging behaviour4. Plant volatiles are reliable and easily detectable cues for carnivores, and the plant benefits from attracting natural enemies of the herbivore. Marcel Dicke focused on the specificity of the plant signals, and the observation that different herbivores can induce quantitatively and
Mechanisms – proximate functions
Jim Tumlinson (USDA, Gainesville, USA) described the isolation and identification of the elicitor, volicitin, from the saliva of beet armyworm caterpillars5. Cotton plants respond to herbivore attack by de novo synthesis of volatiles that attract parasitoids (Fig. 1). Caterpillar saliva induces the production of volatiles (predominantly terpenoids) when applied to damaged leaves, which in turn attracts the parasitoids. Interestingly, volicitin contains a linoleic acid moiety that is derived
Learning from pathologists
Pathologists are well advanced in understanding how a plant responds to attack by a pathogen. Thus, the presentations by pathologists, at this predominantly entomological symposium, were well received and highlighted the tremendous multi-disciplinary nature of research in this field. Bob Dietrich (Novartis, Research Triangle Park, NC, USA) described work on the commercially available salicylic acid analogue (Bion®), which is sprayed onto wheat plants to induce systemically acquired resistance
The road ahead
The continuing development of biotechnology should help to push forward our understanding of induced chemical plant defences. Tom Mitchell-Olds (Max Planck Institute, Jena, Germany) promoted Arabidopsis as the ideal model plant for studying insect–plant interactions. The mapping of the Arabidopsis genome opens up considerable opportunities and will allow the genetic approach used by pathologists to be adopted by entomologists, even though insect behaviour is a complicating factor when studying
Acknowledgements
My thanks to Ted Turlings, who kindly supplied the material for the figure.
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