Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2007
Publication Date: 7/1/2007
Citation: Naik, D., Dhanaraj, A.L., Arora, R., Rowland, L.J. 2007. Identification of cold-responsive genes in blueberry (Vaccinium corymbosum L.) using a hybridization approach. Plant Science. 173: 213-222
Interpretive Summary: Blueberry is an important small fruit crop in the U.S. that is rich in health-promoting nutrients. Depending on the year, however, damages from winter freezes and spring frosts can result in significant losses in fruit yield to blueberry growers. In woody plants, like blueberry, gradual exposure to low temperature is required for plants to develop cold hardiness in the fall, and, thus, be ready to face extreme temperatures later in the winter. Genetic evidence from numerous plants indicates that expression of many genes is required for sufficient cold acclimation. By studying the genetics of cold acclimation, scientists hope to develop more cold hardy blueberry cultivars. Here, a procedure known as subtractive hybridization was used to identify many genes potentially related to development of cold hardiness in blueberry. Some of these include master switches that may turn on the expression of whole families of genes. These genes are now available for scientists to test their involvement in development of cold hardiness directly.
Technical Abstract: Enhanced cold tolerance, including tolerance to winter freezing and spring frosts, is needed for genetic improvement of current highbush blueberry (Vaccinium corymbosum L.) cultivars. To gain a better understanding of changes in gene expression associated with development of cold tolerance in blueberry and other woody perennials, forward and reverse subtracted cDNA libraries were prepared in such a way to enrich for transcripts that are expressed at higher levels in blueberry flower buds at 400 hours and at 0 hours of low temperature exposure, respectively. Of the clones picked and single-pass sequenced, 503 clones from the forward subtracted library and 167 clones from the reverse subtracted library had inserts and yielded high quality sequences; and of these, 291 (57.9%) and 51 (31.0%), respectively, were assigned putative identities from BLAST searches of GenBank. From contig analyses to cluster genes of like or identical sequences, 275 unigenes (unique clones) from the forward subtracted library and 99 unigenes from the reverse subtracted library were obtained. Many potential cold and light-stress related genes were identified from the forward subtracted library and many genes encoding putative transcription factors and other proteins related to signal transduction were identified from both the forward and reverse subtracted libraries. Eleven genes of interest (six from the forward subtracted library and five from the reverse subtracted library) were selected and their expression was analyzed in floral buds by quantitative real-time RT-PCR over a time course from ~0-1200 hours of low temperature exposure. Expression profiles validated the quality of the libraries.