|De Los Reyes, Benildo|
Submitted to: icfai University Journal of Genetics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2009
Publication Date: 2/5/2009
Citation: Antoine, W., De Los Reyes, B.G., Miernyk, J.A., Stewart, J.M. 2009. Molecular Evolution of the Plant SLT Protein Family. icfai University Journal of Genetics and Evolution. 2:56-73. Interpretive Summary: The ability of plants to respond to environmental stress is a major factor in agricultural productivity. Plants cannot move, so when subjected to abrupt changes in environmental conditions, such as salt or water stress, they respond by switching off normal housekeeping activities and switching on elements of the stress response network. A key component of the rice stress network was identified and analyzed. Proteins closely related to the rice stress protein can be found in other plants, but are not present in bacteria, fungi, or animals. The evolution of the rice stress protein was studied, and the ancient origin of this protein was proposed. This information will be important to researchers in their attempts to alter the ability of plants to respond to environmental stress, and to other plant scientists who will try to design more efficient crop plants through either classical breeding or biotechnology.
Technical Abstract: The products of the sodium/lithium tolerance (Slt) genes are proteins that have molecular chaperone activity in vitro. The results from extensive database analyses indicate that SLT-orthologous proteins are present only in seed plants (Spermatopsida). Herein we describe the sequence analysis of the three Slt genes from rice (Oryza sativa, japonica cultivar-group), and a phylogenetic analysis of SLT. The deduced amino acid sequences of the protein encoded by OsSlt1 and OsSlt2 are more than 60% similar, and include the same functional domains. Despite this, they comprise distinct sub-families and their phylogenetic relationship can be used to classify orthologous proteins from other species. These genes appear to be the result of an ancient fusion event between a plant viral-response protein-like progenitor and a small heat shock protein. Analysis of rate of substitution results suggests that the Slt genes have evolved under purifying selection. Their evolution has included acquisition of short Gly- and Pro-rich sequences within the N-terminal portion of the protein that might be involved with protein interactions. Evolution within the gene family does not appear to follow the molecular clock; the two sub-families diverged after the divergence of monocots and eudicots.