Response of Dehydrins to Drought, Low Temperature, and ABA Treatment in Whole Plants and Cell Suspension Cultures of Blueberry

Previously, three dehydrins of 65, 60, and 14 kDa 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. Recently, a dehydrin cDNA clone was isolated and sequenced, and shown to hybridize to messages likely to encode all three dehydrins. In the present study, expression of dehydrins was examined in blueberry cultivars in response to drought and low-temperature treatment and in cell suspension cultures in response to low temperature and ABA 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. Cell suspension cultures were held at 4 °C for up to 2 weeks. For ABA experiment, ABA concentrations ranging from 10-3 to 10-7 M were used. Dehydrins were monitored in response to various treatments at RNA and proteins levels using the cDNA clone and antisera raised against the dehydrins. Interestingly, a previously uncharacterized 30 kDa dehydrin was found to be the major low temperature and ABA-responsive protein in cell suspension cultures.