Finding flavor genes

A key enzyme involved in flavor biogenesis in ripening strawberries has been discovered using customized cDNA microarrays.
Identification of the SAAT Gene Involved in Strawberry Flavor Biogenesis by Use of DNA Microarrays
Fruit flavor is a result of a complex mixture of numerous compounds. The formation of these compounds is closely correlated with the metabolic changes occurring during fruit maturation. Here, we describe the use of DNA microarrays and appropriate statistical analyses to dissect a complex developmental process. In doing so, we have identified a novel strawberry alcohol acyltransferase (SAAT) gene that plays a crucial role in flavor biogenesis in ripening fruit. Volatile esters are quantitatively and qualitatively the most important compounds providing fruity odors. Biochemical evidence for involvement of the SAAT gene in formation of fruity esters is provided by characterizing the recombinant protein expressed in Escherichia coli. The SAAT enzyme showed maximum activity with aliphatic medium-chain alcohols, whose corresponding esters are major components of strawberry volatiles. The enzyme was capable of utilizing short- and medium-chain, branched, and aromatic acyl-CoA molecules as cosubstrates. The results suggest that the formation of volatile esters in fruit is subject to the availability of acyl-CoA molecules and alcohol substrates and is dictated by the temporal expression pattern of the SAAT gene(s) and substrate specificity of the SAAT enzyme(s).
Cytochrome P-450 dependent (+)-limonene-6-hydroxylation in fruits of caraway (Carum carvi)
Abstract Microsomal preparations from fruits of annual and biennial forms of caraway (Carum carvi L.) catalyze the C-6 hydroxylation of (+)-limonene to (+)-trans-carveol, the key intermediate in the biosynthesis of carvone. The enzyme activities from both caraway forms had similar properties (pH optimum, Km, cofactor requirements, etc). Both activities were dependent on NADPH and O2, and were inhibited by N-substituted imidazoles, metyrapone, cytochrome c and CO, and thus meet many of the established criteria for cytochrome P-450-dependent mixed function oxygenases.