Analysis of gene expression associated with cold acclimation in blueberry floral buds using expressed sequence tags

Abstract To gain a better understanding of changes in gene expression associated with cold acclimation in the woody perennial blueberry ( Vaccinium spp.), a genomics approach based on the analysis of expressed sequence tags (ESTs) was undertaken. Two cDNA libraries were constructed using RNA from cold acclimated and non-acclimated floral buds of the blueberry cultivar Bluecrop and about 600 5′-end ESTs were generated from each of the libraries. About 100 3′-end ESTs were generated from the cold acclimated library as well. Putative functions were assigned to 57% of the cDNAs that yielded high quality sequences based on homology to other genes/ESTs from Genbank, and these were classified into 14 functional categories. From a contig analysis, which clustered sequences derived from the same or very similar genes, 430 and 483 unique transcripts were identified from the cold acclimated and non-acclimated libraries, respectively. Of the total unique transcripts, only 4.3% were shared between the libraries, suggesting marked differences in the genes expressed under the two conditions. The most highly abundant cDNAs that were picked many more times from one library than from the other were identified as representing potentially differentially expressed transcripts. Northern analyses were performed to examine expression of eight selected transcripts and seven of these were confirmed to be preferentially expressed under either cold acclimating or non-acclimating conditions. Only one of the seven transcripts, encoding a dehydrin, had been found previously to be up-regulated during cold acclimation of blueberry. This study demonstrates that analysis of ESTs is an effective strategy to identify candidate cold acclimation-responsive transcripts in blueberry.