Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: W56 - GENES IN THE BIOSYNTHESIS OF SECONDARY PRODUCTS
W56
GENES IN THE BIOSYNTHESIS OF SECONDARY PRODUCTS
PRICE, CARL A., ELLEN M. REARDON
ISPMB Commission on Plant Gene Nomenclature, Waksman Institute, Rutgers University, Piscataway, NJ USA
More than 25,000 discrete substances have been isolated from plants, with whole sets of molecules found to be specific to individual plant families, genera, species or even varieties. Taxol, a spectacular example, is only one compound among the class of taxanes, whose complex chemistry and pathways of biosynthesis are largely limited to the genus Taxus. Simpler examples of diverse secondary products in plants include alkaloids, sugars and polysaccharides, and carotenoids and terpenoids. The Commission on Plant Gene Nomenclature (CPGN) has a simple model: all genes encoding substantially similar products are assigned to the same gene family, and that gene family is given the same name across the plant kingdom. Among higher plants, for example, there are ten kinds of proteins of the light-harvesting complex and ten kinds of chitinases. The CPGN recognizes ten gene families (Lhca1, Lhca2, ..., Lhcb1, ...) encoding proteins of the light-harvesting complex, and ten gene families encoding chitinases (Chia1, Chia2, ..., Chib1, ...) It is important to note that, in general, these gene families are conserved among all kinds of angiosperms. We have come to expect that most genes in higher plants will be aligned similarly, so that housekeeping genes, which probably account for 90 to 95 percent of plant genomes, can be represented within 6,000 to 8,000 gene families. But does the cornucopia of chemical structures represented in secondary products correspond to a similarly conserved set of gene families, or is there as wide a diversity of genes as there are secondary products? The answer to this question will be important for the CPGN's goal of generating a common nomenclature for sequenced plant genes. We shall address this question by focusing on some of the information now accumulating on genes involved in the synthesis of secondary products, especially of carotenoids and terpenoids.