EFFECTS OF DROUGHT AND COLD STRESS ON BLUEBERRY DEHYDRIN EXPRESSION

¹ Department of Horticulture, University of Georgia, Athens, GA 30602 USA

² Fruit Laboratory, Beltsville Agricultural Research Center, Agriculture Research Service, Beltsville, MD 20705 USA

Previously three dehydrins of 65, 60, and 14 kD were identified as the predominant proteins present in cold acclimated blueberry floral buds. Levels were shown to increase with cold acclimation and decrease with deacclimation and resumption of growth. Dehydrins are a group of heat stable, glycine-rich plant proteins that are induced by environmental stimuli that cause dehydration, such as drought, low temperature, salinity, and seed maturation. In the present study, expression of dehydrins was examined in several blueberry cultivars in response to drought and low temperature treatment. During 32 days of drought stress, relative shoot water content dropped to 51 to 90% depending upon cultivars. For cold stress experiments, cultivars with different chilling requirements and levels of cold hardiness were kept at 4°C for 5 weeks. Higher level of dehydrins were present in cold hardy and drought tolerant cultivars than in cold and drought sensitive cultivars. In both stress situations, the level of dehydrins was higher in stems than in leaves or roots, but lower than in buds.