IDENIFYING FACTORS AND GENES UNDERLYING APPLE FRUIT POSTHARVEST CHILLING INJURY AND CRISPNESS MAINTENANCE

The major goals of this project are to understand the genes of the Honeycrisp apple variety and its progeny that make them susceptible to storage chilling injuries and lead to their abilities to maintain crispness over long-term cold storage. Meeting these goals will help the apple breeders and industry develop and grow improved apple varieties that will appeal to consumers and decrease storage costs.The objectives of this project are:1) Test the hypothesis that tissue predisposed to chilling injury during storage is physiologically different at harvest from tissue that will not show symptoms of chilling injury after storage. The prediction that results from this hypothesis is that such a difference can be detected at harvest. The goal of this work is to test the ability of various spectroscopic methods to detect differences between individual fruit and / or individual areas of fruit that are susceptible or not to chilling injury.2) Examine expression of genes associated with fruit crispness maintenance in apple genotypes other than those in the 'Honeycrisp' x MN1764 family. Candidate genes involved in postharvest crispness maintenance have been identified in previous work using fruit from a family of trees resulting from crossing 'Honeycrisp' x MN1764. The objective of this work would be to further test the hypothesis that specific candidate genes identified from previous work must be lacking (e.g., polygalacturonase) or continually expressed (e.g., xyloglucan endotransferase) in order for apple crispness to be maintained through many months of postharvest cold storage.