Technical Abstract: Certain strawberry cultivars accumulate acetaldehyde, ethanol and ethyl acetate in response to high concentrations of CO2 (20%) during storage, while in others the presence of these volatiles is not detectable. Our goal is to identify differentially expressed genes between cultivars with these different fermentative responses in an effort to dissect molecular elements involved in this effect. A tomato cDNA microarray containing approximately 12,000 ESTs (8,700 unigenes) was utilized to compare gene expression differences between strawberry genotypes with different responses to CO2. Additionally, this tool will also allow for comparisons between climacteric and non-climacteric fruit systems. The microarray was hybridized with strawberry RNA extracted from ‘Jewel’, which accumulates fermentation products and ‘Cavendish’, which does not. A set of 81 ESTs showed differential expression between the two cultivars when they were stored in an atmosphere containing 20% CO2 (balance air) for 48hrs. When RNA from fruit stored in air was compared with that from fruit stored in 20% CO2, 178 ESTs were differentially expressed in ‘Jewel’, but only 54 ESTs shown differential expression in ‘Cavendish’ between fruit stored in air and CO2 . Genes with putative homology to enzymes involved in cell wall metabolism, protein synthesis and stress have been identified.