Submitted to: Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2000
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 analysis of three genes we have isolated from T. ruralis that code for ribosomal proteins. These protein are integral proteins in the protein synthetic machinery of the cell. These gene are expressed under all conditions which establishes its importance to the plants cells in maintaining function under drying and rehydrating conditions. We have also determined that the Tortula genes are very similar to those isolated from crops This report forms the foundation for future studies into the importance of this gene in maintaining cell integrity during drought.
Technical Abstract: One of the key aspects of desiccation tolerance in plants is the maintenance of cellular components in stable and viable forms in the desiccated state, particularly those related to the translational apparatus. This study investigated the mRNA stability and gene control of a third integral component of the translational apparatus, the ribosomal proteins in the desiccation tolerant moss Tortula rurali. Three cDNAs encoding predicted polypeptides with similarity to ribosomal proteins were isolated from a desiccated gametophyte cDNA library; Rps14 and Rps16 encode the small-subunit ribosomal proteins S14 and S16, respectively and Rpl23 encodes the large-subunit ribosomal protein L23. RPS14, RPS16 and RPL23, the deduced polypeptides, have predicted molecular masses of 14.4 kDa, 16.2 kDa and 14.9 kDa and predicted pI's of 11.08, 10.34 and 10.67 respectively. Phylogenetic analysis of deduced amino acid sequences demonstrated each of the T. ruralis proteins is most similar to ribosomal proteins from higher plants even though RPS14 andRPL23 show high divergence from their other plant counterparts. Northern blot hybridizations of polysomal RNAs demonstrated that Rps14, Rps16 and Rpl23 are constitutively expressed in moss gametophytes during a wet/dry/wet cycle. Our findings clearly demonstrated that Rps14, Rps16 and Rpl23 transcripts are maintained in the dried state as conserved mRNAs.