Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/1998
Publication Date: N/A
Interpretive Summary: This work describes the identification of a gene (named cor20) that is "turned on" in the perennial weed, leafy spurge, when the plant is subjected to growth conditions that cause it to become more freezing tolerant. Cor20 is turned on within 48 hours after the plant is placed at 5 C, and remains active for as long as the plant is maintained at these temperatures. Cor20 is turned on in roots, stems and leaves of cold treate plants. When the plant is returned to normal growing temperatures, cor20 is turned off, and its expression drops to background levels in less than 24 hours. Cor20 is turned on all the time in undifferentiated plant tissue grown in culture. Cor20 is not turned on by drought stress or heat stress. Sequence analysis of cor20 indicated that it was very similar to a number of other genes which appear to bind RNA and are very rich in glycine. Some of these other glycine-rich RNA-binding proteins have been shown to be turned on by various environmental stresses such as cold, wounding, and pathogen attack.
Technical Abstract: Leafy spurge (Euphorbia esula) is a perennial weed which is capable of acclimating to sub-freezing temperatures. We have used the differential display technique to identify and clone a cDNA for a cold regulated gene (cor20) whose mRNA accumulates specifically during the cold acclimation process. The expression of cor20 was analyzed, and it has been determined that the RNA from this gene reaches maximal expression in less than two days following exposure of the plant to temperatures of 5 C, and remains at high levels in the plant for at least 30 days so long as the plant is left in the cold. Expression of cor20 drops to control levels within 24 hours when the plant is returned to normal growing temperatures. Cor20 transcript does not accumulate under conditions of drought or heat stress. The cor20 gene is induced in response to low temperatures in roots, stems and leaves, but is expressed constitutively in tissue culture at control temperatures. Southern blot analysis indicates that the cor20 gene is a member of a gene family. The cor20 cDNA was used to isolate a genomic clone. Sequence analysis of the genomic clone indicated that it shares considerable homology to a group of glycine-rich RNA-binding proteins, some of which have also been shown to be cold regulated.