natural-products-in-plant-pest-management

Biotechnology and Natural Product Synthesis 265morphology, but differences in their genetic makeup. Molecular biologicaltools, based on DNA, protein or secondary metabolites, provide additionaltaxonomic markers to supplement information gathered through classicaltaxonomical methods for further characterization. This enables the identificationof variants not only at species or subspecies levels, but tracing downto variations between two individuals. Such biotechnological approachesthus enable the identification of more useful genotypes for exploitation innatural product synthesis. Identification of more useful genotypes is obviouslyvery useful in the conservation of genetic diversity. Systematic studiescan indicate which genomes to search, sample and study for useful products.Systematics also provides answers to questions relating to the evolution ofchemical and physical structures and their synthesis or ontogeny.The biotechnological tools available for systematics are protein profiles,polysaccharides, plasmids, DNA–DNA hybridization, various PCR-basedtechniques and DNA sequencing and alignment. With the assistance of bioinformatics,the molecular data are processed and phylogenetic relationshipsare generated. This facilitates the search for a better performer withinproducers of a known product or the search for new products, by narrowingdown the scope of the search. Certain traits have evolved only once andtherefore will only be present within a single clade or very closely relatedclades, rather than being present randomly across diverse organisms. For anexample in bioproducts, taxol is known to be present in the yew family,Taxaceae. Therefore if one is interested in discovering other organismsproducing taxol, the most logical approach would be to start the quest fortaxol and other taxanes in plants closely related to Taxaceae family. Theother sister family most closely related is Podocarpaceae and taxane hasbeen found in Podocarpus gracilior for the first time outside Taxaceae ( Stahlhutet al., 1999). The story of mustard oil or mustard glucosinolates is adifferent one. With the exception of the genus Drypetes (a member ofMalpighiales), all the other mustard oil producers are in families belongingto one ordinal clade, Brasicales. As order Brasicales and genus Drypetes arephylogentically distant, one can assume that mustard oil biosynthesisevolved twice (Rodman et al., 1993). This is confirmed by the presence oftwo different biosynthetic pathways. Therefore, although the final productis the same, the evolution of the biosynthetic pathway is different. Thisinformation is extremely important in the search for alternative pathwaysfor the synthesis of natural products (i.e. one has to search in distantlyrelated clades).Molecular tools are extremely sensitive in revealing minor differences inclosely related genotypes within a species. As discussed elsewhere in thischapter, identifying genotypes of interest in bioproduct formation is particularlyimportant for exploitation, but not restricted to that. This is equally ormore important in conservation strategies. A genotype once lost shall not beable to be reconstituted. Exploring possibilities of making use of other biotechnologicaltools such as plant-cell and organ culture also help preservethe plants in the field. In addition, micropropagation using tissue culturetechniques is useful in this context.