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Title: Molecular Genetic and Physiological Analysis of the Cold-Responsive Dehdrins of Blueberry

Authors
item Rowland, Lisa
item Panta, G. - UNIVERSITY OF TENNESSEE
item Mehra, S. - UNIV OF DELHI, INDIA
item Parmentier-Line, C. - UNIVERSITY OF MARYLAND

Submitted to: Journal Of Crop Production
Publication Acceptance Date: November 9, 2001
Publication Date: September 20, 2004
Citation: Rowland, L.J., Panta, G.R., Mehra, S., Parmentier-Line, C. 2001. Molecular Genetic And Physiological Analysis Of The Cold-Responsive Dehdrins Of Blueberry. Journal Of Crop Production. 10:53-76

Interpretive Summary: Because the development of more cold hardy varieties is an important need to the blueberry industry, our laboratory has been working on identifying and isolating genes that control cold hardiness in blueberry. We have identified three abundant proteins that are induced during cold acclimation and their accumulation is closely associated with cold hardiness levels. These proteins are a type of plant protein induced by cold and drought stress, known as dehydrin, and are good candidates for controlling cold hardiness in blueberry. In order to isolate the genes encoding these dehydrins, we used a previously isolated dehydrin gene of blueberry (blueberry dehydrin 1) to probe our blueberry cDNA library (collection of clones representing genes expressed in blueberry flower buds during the winter) for related genes and pulled out four additional dehydrin clones. All were sequenced and their sequences compared to each other and to blueberry dehydrin 1. On one end all the sequences were identical but diverged more toward the opposite end, suggesting the conserved end may play an important function. Isolation of genes associated with cold hardiness and winter survival will help scientists to develop more effective strategies for increasing cold hardiness of existing varieties or developing new, more cold-hardy varieties of blueberry.

Technical Abstract: Lack of winter hardiness and susceptibility to spring frosts are two of the most important genetic limitations of blueberry cultivars. These traits are influenced by factors such as the level of cold hardiness reached while plants are in the cold acclimated state and the chilling requirement or amount of low temperature exposure required for breaking dormancy. For these reasons, we are investigating genetic controls of chilling requirement and cold hardiness in blueberry. Previously, we identified three dehydrins (plant proteins that are induced by drought and low temperature) of 65, 60, and 14 kDa as the predominant proteins present in cold acclimated blueberry floral buds. Levels of the dehydrins increase with cold acclimation and decrease with deacclimation and resumption of growth. More recent expression studies indicate that blueberry dehydrins are induced by cold stress in all organs examined including floral buds, leaves, stems, and roots, and by drought stress in primarily stems. Here, the previously isolated full-length cDNA clone bbdhn1, encoding the 60 kDa dehydrin, was used to screen our cDNA library, prepared from RNA from cold acclimated blueberry floral buds, and resulted in the isolation of four additional dehydrin cDNAs. All were sequenced and the sequences compared to that of the bbdhn1 cDNA. Sequences were identical at the 3' end and diverged more as they approached the 5 foot end. Whether the cDNAs represent different genes or a combination of different alleles and different genes remains to be determined.

   
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