No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The effect of natural herbivory on the secondary metabolism of Myrica gale was investigated. In a field experiment herbivory was found to elicit changes in both the leaf phenolics and the density of volatile oil glands. Lygocoris spinolai, a capsid bug, accounted for most of the observed herbivory. One set of plants (the controls) were kept free of insect herbivores while a second set sustained capsid bug herbivory. The terpenoid and phenolic profile of leaves from each set was obtained on a weekly basis using GLC and IIPLC respectively. GC-MS was used to identify constituents of the volatile oil. UV, ¹H and ¹³C NMR, El-MS and FAB-tlS were used to identify the phenolics. Capsid bug damage induced a cpialitative change in the phenolic content of the leaves. This induction revealed a new compound, kaempferol-3-(2,3-diacetoxy-4-p-coumaroyl)rhamnoside, which was isolated and identified. The leaves also proved to contain other flavonoids, the concentrations of which were not affected by herbivory. Artificial damage was observed to elicit a quantitative change in leaf phenolics, thus having a different effect than herbivore damage. Herbivore damage also induced quantitative changes in the volatile oil by eliciting gland production whilst having no effect on the composition of the oil. The induced flavonoid and the volatile oil were tested for fungal growth inhibitory properties. Both were found to have marked antifungal activity at low concentrations when tested against fungal species isolated from the leaves of M. gale in the field. The observed phenomena are discussed in terms of defenses against herbivores and pathogens. The relationship between the nitrogen economy of M. gale and leaf chemistry is also discussed.

No description available.

<p>To date five classes of resistance proteins have been identified in plants and these include the intracellular protein kinases, receptor-like protein kinases with extracellular leucinerich repeat (LRR) domain, LRR proteins that encode membrane bound extracellular proteins, toxin reductase and intracellular LRR proteins with a nucleotide-binding site (NBS). These proteins recognise &ldquo / invading pathogen&rdquo / and in turn trigger defence response systems that act to protect plants from invading pathogens. The NBS-LRR genes which constitutes the major class encode a family of resistance proteins that are made up of a centrally located nucleotide binding site domain and a C-terminal leucine rich repeat receptor. This class of genes constitute the largest family of resistance genes identified in plants to date. They make up the majority of proteins involved in the plant basal and inducible defence systems against pathogen infection.</p>

<p>To date five classes of resistance proteins have been identified in plants and these include the intracellular protein kinases, receptor-like protein kinases with extracellular leucinerich repeat (LRR) domain, LRR proteins that encode membrane bound extracellular proteins, toxin reductase and intracellular LRR proteins with a nucleotide-binding site (NBS). These proteins recognise &ldquo / invading pathogen&rdquo / and in turn trigger defence response systems that act to protect plants from invading pathogens. The NBS-LRR genes which constitutes the major class encode a family of resistance proteins that are made up of a centrally located nucleotide binding site domain and a C-terminal leucine rich repeat receptor. This class of genes constitute the largest family of resistance genes identified in plants to date. They make up the majority of proteins involved in the plant basal and inducible defence systems against pathogen infection.</p>