A cDNA library was made by subtractive hybridization of cDNA from non-harvested and harvested alfalfa plants. One cDNA clone, hi7, in Northern blot analysis showed a high level of transcription of this gene in harvested tissue, but not in non-harvested tissue, nor in wounded or heat shock treated tissue. A 640 bp promoter region isolated by genomic walking based on hi7 cDNA sequence, was fused to a GUS gene and transferred to tobacco and Medicago truncatula. When leaf tissue from transgenic tobacco plants was harvested, incubated for 24 h at room temperature, and then stained for GUS activity, a strong blue colour was observed throughout the tissue, but not in tissue that was stained immediately following harvesting. The expression of the GUS gene was also induced in tobacco plants sprayed with abscissic acid (ABA) and in callus derived from these plants when transferred to medium containing ABA.
