Biochemical, Molecular Genetic and Evolutionary Aspects of Defense-Related Terpenoid Metabolism in Conifers
Résumé
Conifers (order Coniferales) are the largest and most diverse group of living gymnosperms comprising more than 600 species of 60-65 genera in seven families, including the Pinaceae, Podocarpaceae, Araucariaceae, Taxaceae, Cephalotaxaceae, Taxodiaceae, and Cupressaceae.1., 2. Their origin can be traced back to 300 million years (upper Carboniferous) according to fossil records, and their peak of abundance occurred about 150 million years ago at the Jurassic-Cretaceous boundary. Cladistic analyses based on nuclear 28S rRNA sequences and other molecular and morphological data demonstrate that conifers are a monophyletic group with the pine family (Pinaceae) having been the first to diverge from the rest of the assemblage.2 At present, conifers are dominant members of many forest ecosystems. In the northern hemisphere, conifers are among the most important species for the production of wood and fiber. In addition to their taxonomic abundance, ecological dominance, and evolutionary persistence, conifers are also noted for their ability to form an enormous array of natural products, including soluble and insoluble phenolics, alkaloids of the 2,6-disubstituted piperidine type, and a large variety of terpenoids (isoprenoids).