GENETIC AND BIOCHEMICAL MECHANISMS DETERMINING FRESH PRODUCE QUALITY AND STORAGE LIFE

The goal of this project is to facilitate development of new genetic lines of fruits and vegetables that are superior with respect to sensory quality, storage life, and betterment of human health by providing breeders with the knowledge and molecular tools they require. Research over the next 5 years will pursue the following two broad objectives: Objective 1) Determine molecular mechanisms governing natural and stress-induced deterioration of fresh produce quality during postharvest storage and shelf life; and Objective 2) Identify, clone, and manipulate key genes regulating accumulation or loss of phenylpropanoids and other health-beneficial secondary metabolites in stored whole and fresh-cut fruits and vegetables. The initial phase under objective 1 will aim to identify and clone both regulatory and metabolic genes potentially involved in ripening, senescence, and responses to stress (e.g. low temperature) in fresh fruits and vegetables. Primary focus will be on genes and encoded proteins regulated by calcium, which is known to retard senescence and mitigate certain stress disorders, and on genes/enzymes directly involved in degradation of cell membranes. Gene silencing and other molecular strategies will then be used to confirm the critical role of specific genes/enzymes in ripening, senescence, and stress responses. This will provide target genes for manipulation or germplasm screening to yield new lines of produce with extended storage life and resistance to stress disorders. Under objective 2 there will be two foci. The first is to identify and clone genes that can be manipulated to enhance accumulation, retention, and/or bioavailability of anthocyanins (red pigments) and other flavonoids in sweet cherry and strawberry. Dietary intake of this group of plant chemicals is known to confer protection against cardiovascular disease, diabetes, cancer, and stroke. The second pursuit under objective 2 will be to identify, clone, and manipulate key genes in biosynthesis of health-beneficial hydroxycinnamic acid conjugates in wild germplasm of eggplant and tomato that can be transferred to commercial lines to yield new functional foods.