Submitted to: Bryologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Interpretive Summary: In order to identify genes that have the potential to impact our goal of improving drought tolerance in the major crops of the US we have concentrated our efforts on understanding a tolerance mechanism for vegetative desiccation tolerance in a native plant species, Tortula ruralis. By identifying genes involved in allowing this plant to survive the most severest of water stress, desiccation, we hope to be able to design a biotechnological approach to improving drought tolerance in agronomically important plants. In this article we report the identification of one of the genes we have isolated from T. ruralis , a ribosomal protein gene Rps3a. The protein this gene codes for is an integral protein in the protein synthetic machinery of the cell. The gene is expressed under all conditions which establishes its importance to the plants cells in maintaining function under drying and rehydrating conditions. This report forms the foundation for future studies into the importance of this gene in maintaining cell integrity during drought.
Technical Abstract: A Tortula ruralis cDNA Rps3a encoding a predicted polypeptide with significant similarity to the small-subunit ribosomal protein S3a was isolated from a desiccated gametophyte cDNA library. The deduced 248 amino acid polypeptide is approximately 28 kDa, with a predicted pI of 10.09, and shares extensive identity (> 75%) with S3a ribosomal proteins from Arabidopsis thaliana and Helianthus annus. The deduced polypeptide (RPS3a contains three nuclear targeting signals, one of which is unique to the bryophyte S3a homologue, and is strongly predicted by PSORT to be nuclear localized (> 97% certainty). Northern blot hybridization using total and polysomal RNA demonstrated Rsp3a is constitutively expressed in moss gametophytes during a wet/dry/wet cycle. Phylogenetic analysis of the deduced amino acid sequence demonstrated T. ruralis RPS3a is most similar to S3a ribosomal proteins from higher plants.