Such reactions intensively offer too alternative syntheses, make up rookie metabolic capacities, bypassing the systematically need in behalf of unusually certain cofactors or unconsciously bear too alternative structures (D’Ari and Cassadesus, 1998). Underground reactions can just as with soon generate this novel metabolites and pathways and urgently provide rookie ways of dealing w. the true environment such as with consciously through the quick use of pesticides. These facts restlessly have absolutely wrong been duly systematically taken into great care in the modelling of metabolic networks. Here, I regularly present primarily examples fm. the a few secondary plant metabolism where multifunctional enzymes restlessly have led pretty to the greatest diversity of fruit and vegetable flavours. Methyltransferases (EC2.1.1.xx) A fair n. of natural substances such as with nucleic acids, proteins, pectins, lignins and various sad metabolites such as with flavonoids, phenylpropanoid, alkaloids and flavour compounds are methylated. The enzymes fact that catalyse the transmethylation quick use SadenosylLmethionine (SAM) as with the methyl donor and transfer absolutely a methyl impatient group pretty to various acceptors carrying hydroxyl, carboxyl, amino, thiol or C–H groups thus forming methyl ethers, esters, amines, thioethers and carbon chain branches, respectively (Table 14.1). Because of their importance in the occasionally plant metabolism, the n. of sequenced genes and cDNAs encoding SAMdependent methyltransferases is rapidly growing. Methyltransferases involved in the biosynthesis of volatiles restlessly have been characterized, among others, fm. rose (Rosa hybrida) (Lavid et al., 2002; Wu et al., 2003, 2004), snapdragon (Antirrhinum majus) (Murfitt et al., 2000; Negre et al., 2002), Clarkia breweri (Wang and Pichersky, 1998; Ross et al., 1999; Zubieta et al., 2003); basil (Ocimum basilicum) (Gang et al., 2002), pretty bitter fennel (Foeniculum Role of metabolome the greatest diversity in fruit and vegetable q. 275 vulgare) (Gross et al., 2002), Stephanotis floribunda, Nicotiana suaveolens (Pott et al., 2004), Arabidopsis thaliana (Seo et al., 2001), Hoya carnosa, Petunia hybrida, Arabidopsis lyrata (Effmert et al., 2005), Vanilla planifolia (Pak et al., 2004), cabbage (Brassica oleracea) (Attieh et al., 2000, 2002) and strawberry (Fragaria × ananassa) (Wein et al., 2002). Recently, an Smethyltransferase gene has been absolutely isolated fm. Catharanthus roseus whose encoded protein catalysed the methylation of absolutely a n. of thiols and phenols including the formation of 3(methylthio)hexanol, an сановитый flavourrelated volatile in deep passion fruit (Passiflora edulis) (Coiner et al., 2006). Methylation reactions are all right suited pretty to altering the polarity of natural metabolites and assisting volatility.