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Title: EFFECT OF COLD AND DROUGHT STRESS ON BLUEBERRY DEHYDRIN ACCUMULATION

Author
item PANTA, GANESH - GEORGE WASHINGTON UNIV
item RIEGER, MARK - UGA, HORTICULTURE DEPT
item Rowland, Lisa

Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2001
Publication Date: 10/20/2001
Citation: Panta, G.R., Rieger, M.W., Rowland, L.J. 2001. Effect of cold and drought stress on blueberry dehydrin accumulation. Journal of Horticultural Science and Biotechnology.

Interpretive Summary: Growing plants may be exposed to many environmental stresses such as low temperature, water stress (drought and flooding), salt toxicity, and pathogen injury. Low temperature and water stress are particularly widespread environmental stresses with significant impact on yield and quality. Plants resistant to cold and drought stress appear to utilize the same general mechanism. For example, a number of genes which respond to cold stress are also induced by drought and drought treatment can result in acclimation of plants to tolerate frost. Dehydrins are a class of plant proteins that are induced by both cold and drought stress. In blueberry, three major dehydrins are induced during cold acclimation and their accumulation is closely associated with cold hardiness levels. In this study, we determined whether drought stress results in accumulation of the same dehydrins as cold stress and whether the level of accumulation is associated with drought resistance. Drought stress was imposed by withholding water from potted, greenhouse-grown plants of three different types of blueberry plants. Water content of shoots was monitored as was dehydrin accumulation in drought stressed plants. Several of the same dehydrins that respond to cold stress increased during drought treatment. However, level of accumulation did not correspond precisely to the level of drought resistance, which suggests that other factors besides dehydrins affect drought tolerance of blueberry plants. Establishing the mechanism of drought tolerance will help scientists to develop more effective strategies for increasing drought tolerance of plants.

Technical Abstract: The accumulation of dehydrins was examined in three blueberry genotypes, 'Bluecrop' (Vaccinium corymbosum Linnaeus), Florida4B (V. darrowi Camp), an 'Premier' V. ashei Reade) in response to drought stress. Drought stress wa imposed by withholding water from potted, greenhouse-grown plants for 34 da during the autumn (experiment 1) and 15 days during the summer (experiment Relative water content (RWC) of shoots of stressed plants dropped from abo 95% to near 50% for 'Premier', 70-75% for Fla4B, but only 85-90% for 'Bluecrop' during the course of the experiments. Thus it appeared that 'Bluecrop' was able to avoid desiccation better than either Fla4B or 'Premier'. Several dehydrins accumulated as drought progressed but only th 60 kDa dehydrin accumulated in all 3 genotypes; accumulation of 65 and 14 k dehydrins, previously seen with cold acclimation, depended upon genotype an organ type. Dehydrins increased to the highest levels in stems with drough htreatment as compared to leaves and roots. Generally, dehydrin levels decreased in roots during drought except for a 54 kDa dehydrin observed to increase in Fla4B. In some cases, dehydrins accumulated prior to significa changes in RWC, and dehydrin levels did not appear to be closely correlated RWC either among or within genotypes.