Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 24, 2001
Publication Date: N/A
Interpretive Summary: A gene, designated Tr288, was isolated from a moss capable of surviving complete drying. The isolated gene is also turned on in moss under several environmental stresses such as high salt and high temperature. The Tr288 gene consists of many copies (15) of a repeated segment and is predicted to produce a protein product that contains corresponding repeated protein segments. The protein product is similar to other gene products produced by different plants in response to dehydration. It is hoped that by understanding how the Tr288 contributes to the moss's ability to survive drying it will be possible to enhance the resistance of crops to water, salt and heat stresses.
Technical Abstract: A genomic and cDNA clone for the rehydration-associated (rehydrin) gene, Tr288, were isolated from the desiccation tolerant moss, Tortula ruralis, and their sequences determined. Use of the Tr288 cDNA clone as a molecular probe indicates that Tr288 is most likely a single copy gene whose mRNA accumulates in response to; slow drying, salt (NaCl), thermal, and osmotic stresses. Messenger RNA levels for Tr288 are also enhanced during rehydration after rapid drying of moss gametophytic tissue. The Tr288 cDNA genomic DNA sequences and the resulting deduced protein sequence were compared to sequences available in GenBank and showed significant homology only to members of the dehydrin class of Late Embryogenesis Abundant (LEA) genes. The detected sequence homology is confined to the very C-terminus of theTr288 gene and consists of a single copy of the dehydrin K-box or segment. The 288 gene lacks any of the other common structural elements (poly Ser, Y-box) associated with most dehydrin genes. The most striking feature of the Tr288 gene is the presence of a repeated (fifteen copies) sequence element (the GPN segment) that, similar to repeats observed in several LEA gene families, is predicted to encode amphipathic, alpha helical domains. The large number of GPN repeats suggests a structural or stoichiometric function for the segment. Although there is some structural similarity between the consensus GPN and dehydrin peptide sequences, the presence of both elements within the same gene strongly implies differing functions for the two domains.