Candidate genes of cuticle formation show characteristic expression in the fruit skin of apple

Based on the Arabidopsis model of production and transport of cuticular components in silico analysis of apple EST and genomic sequences identified candidate genes potentially involved in these processes. Expression profiling of the selected genes in apple leaves and fruit tissues at the stage of full tree ripeness showed them to be active in fruit skin, in some cases in a tissue-specific manner. Apart from sequence conservation, characteristic transcript profiles make these genes likely participants of fruit cuticle formation. Genes with putative functions in the fatty acid elongase complex, wax and cutin modifications, transport and a potential regulator were identified this way. Activity of some of the putative genes can be correlated with the known wax composition of the 'Florina' cultivar. Year-to-year and cultivar specific variations in expression of some of these genes indicate plasticity of lipid biosynthetic pathways in apple. Coordinated expression of several cuticle associated genes further supports their proposed role in cuticular lipid metabolism. The presented data suggest conservation of some key determinants of biosynthesis and transport of cuticular lipids between Arabidopsis epidermis and apple fruit skin.