Major diVerences observed in transcript proWles of blueberry during cold acclimation under Weld and cold room conditions

Our laboratory has been working toward increasing our understanding of the genetic control of cold hardiness in blueberry (Vaccinium section Cyanococcus) to ultimately use this information to develop more cold hardy cultivars for the industry. Here, we report using cDNA microarrays to monitor changes in gene expression at multiple times during cold acclimation under Weld and cold room conditions. Microarrays contained over 2,500 cDNA inserts, approximately half of which had been picked and single-pass sequenced from each of two cDNA libraries that were constructed from cold acclimated Xoral buds and non-acclimated Xoral buds of the fairly cold hardy cv. Bluecrop (Vaccinium corymbosum L.). Two biological samples were examined at each time point. Microarray data were analyzed statistically using t tests, ANOVA, clustering algorithms, and online analytical processing (OLAP). Interestingly, more transcripts were found to be upregulated under cold room conditions than under Weld conditions. Many of the genes induced only under cold room conditions could be divided into three major types: (1) genes associated with stress tolerance; (2) those that encode glycolytic and TCA cycle enzymes, and (3) those associated with protein synthesis machinery. A few of the genes induced only under Weld conditions appear to be related to light stress. Possible explanations for these diVerences are discussed in physiological context. Although many similarities exist in how plants respond during cold acclimation in the cold room and in the Weld environment, there are major diVerences suggesting caution should be taken in interpreting results based only on artiWcial, cold room conditions.