Submitted to: Plant and Cell Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/1999
Publication Date: N/A
Interpretive Summary: In order to increase our understanding of drought tolerance we are investigating the ability of a native species, Tortula ruralis, to survive the severest of drought conditions, vegetative desiccation. In this manuscript we report our first efforts into a genomic approach to determining which genes are of import in conferring vegetative desiccation- -tolerance on this plant. One step in such an approach is to establish an EST data base from which genes can be identified and compared to other genetic systems. EST stands for Expressed Sequence Tags which are basically sequences of genes that are expressed at a certain time, under certain conditions and in certain tissues (they thus become Tags for these criteria). We have established an EST data bank for transcripts associated with desiccation-tolerance (in particular stored transcripts) in Tortula. The EST bank contains 152 sequences from which 29% represent genes previously identified from other systems with the remaining 71% representing novel genes. This report will provide a reference source for those interested in desiccation-tolerance, seed desiccation and , combined with data from other labs across the world, for bryologists.
Technical Abstract: The desiccation-tolerant moss Tortula ruralis [Hedw.] Gaerten., Meyer & Scherb. has both a constitutive protection system and an active rehydration induced recovery mechanism apparently unique to bryophytes. Immediately following rehydration, desiccated T. ruralis gametophytes produce a set of polypeptides whose synthesis is unique to the rehydrated state. We report the construction of a cDNA expression library from the polysomal mRNA of desiccated gametophytes and the single-pass sequencing of randomly selected clones. 152 expressed sequence tags (ESTs) were generated representing more than 60,000 bp of non-redundant DNA sequence. 44 ESTs (29%) demonstrated significant homology to previously identified nucleotide and/or polypeptide sequences, such as ribosomal proteins, desiccation-related peptides, early light-inducible proteins and a V-type ATPase. Analysis of a subset of these homologous ESTs reveals that codon preference in T. ruralis is similar to that of vascular plants, particularly the Magnoliopsida. 108 ESTs (71%) demonstrated no significant homology to deposited sequences and represent a large number of novel plant genes. Analysis of these ESTs will define the range of genes involved in cellular repair and recovery and may provide greater insight to the complex phenotype of vegetative desiccation- tolerance.