The aroma biogenesis-related Olea europaea ALCOHOL DEHYDROGENASE gene is developmentally regulated in the fruits of two O. europaea L. cultivars

Abstract

In plants, the aroma imprint is expressed through well-established and constant ratios between different compounds, which mainly develop through the Lipoxygenase pathway. Such imprint strongly relies on plant genetic traits but can be modulated by exogenous environmental factors. In order to enlarge knowledge on the genetic control underlying aroma biogenesis in olive (Olea europaea L.) drupes, in the present study we characterized one member of ALCOHOL DEHYDROGENASE gene family. The ALCOHOL DEHYDROGENASE activities act along Lipoxygenase enzymatic cascade by interconverting aldehydes into alcohols. The temporal expression pattern of O. europaea ALCOHOL DEHYDROGENASE was monitored by quantitative Real Time-Polymerase Chain Reaction in drupes at different developmental stages (i.e. from light green phase to ripening stage) of two olive cultivars widely used for olive and oil production. The expression of a known LIPOXYGENASE gene (ACG56281.1) was jointly monitored as marker of drupe development. Results were analysed in relation to the spectrum of volatile compounds developed from crushed drupes estimated by Solid-Phase Micro-Extraction method in-line with a Gas Chromatograph/ion trap Mass Spectrometer. The obtained results showed that both cultivar and maturation stage impact on the expression of O. europaea ALCOHOL DEHYDROGENASE gene which in the pathway is co-ordinately modulated with LIPOXYGENASE expression. The transcriptional differences between cultivars appeared to be related to variation of metabolite contents at early developmental stages. The joint role of genes acting in the Lipoxygenase pathway as molecular markers for flavour characteristic of olive drupes is discussed.