Comparative apple-tomato genomics to unravel the 1-mcp effect on apple maturation and ripening

Ethylene is a gaseous hormone that in higher plants controls several physiological aspects. In climacteric species, like apple and tomato, this hormone plays a crucial role triggering and coordinating most of the ripening evolution. To identify the putative gene set impacting the apple fruit ripening, we have carried out a two-way microarray approach: performing homologous and heterologous hybridizations. In the cross species comparison we adopted the genomic resources available for tomato, to date recognized as the reference species for ripening investigation. In our experimental design we characterized the ethylene evolution and fruit softening dynamic over the fruit maturation and ripening of 'Mondial Gala' apple cultivar. To investigate the transcriptome ethylene regulation we applied 1-MCP at harvest, causing an evident distortion in the normal ripening physiology. Functional comparison between control and 1-MCP samples allowed the identification of an ethylene responsive gene set, specifically highlighting elements positively and negatively regulated by 1-MCP. The comparison between the two genomic platforms (homologous and heterologous) enable a preliminary investigation addressed to define a functional orthologous gene set commonly involved in the regulation of the climacteric ripening between the two species.