To identify key genes that are required for stress response, a reverse genetics approach was taken to manipulate expression of candidate genes in plants. In this project, two potential regulatory genes which were originally identified as stress-responsive genes from a microarray experiment in Arabidopsis were examined for their roles in stress tolerance. Over-expression of gene A, which was up-regulated under stress conditions based on the array data, caused earlier flowering and improved plant

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... growth under salinity and dehydration stress conditions at the seedling stage. Over-expression of gene B, which was down-regulated under stress conditions based on the array data, resulted in greater susceptibility to salt and dehydration stress. The null-function mutant of gene A did not show a difference in stress tests compared to control plants, presumably due to functional redundancy of other genes in plants. We propose gene A can potentially be used for stress tolerance improvement in crops.