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 fo rmation of these compounds is closely correlated with the metabolic changes occurring during fruit maturation. Here, we describe the use of DNA microa rrays and appropriate statistical analyses to dissect a complex development al process. In doing so, we have identified a novel strawberry alcohol acyl transferase (SAAT) gene that plays a crucial role in flavor biogenesis in r ipening fruit. Volatile esters are quantitatively and qualitatively the mos t important compounds providing fruity odors. Biochemical evidence for invo lvement of the SAAT gene in formation of fruity esters is provided by chara cterizing the recombinant protein expressed in Escherichia coli. The SAAT e nzyme showed maximum activity with aliphatic medium-chain alcohols, whose c orresponding esters are major components of strawberry volatiles. The enzym e 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 mole cules and alcohol substrates and is dictated by the temporal expression pat tern of the SAAT gene(s) and substrate specificity of the SAAT enzyme(s).