Poster: Temperature responses

Abs # 113: OsSlt1 and OsSlt2: Rice orthologs of the slt gene family, a new heat shock protein family specific to plants.

Presenter:	Antoine, Wesner , wantoin@uark.edu
Authors	Antoine, Wesner  (A)   Stewart, McD James  (A)   De Los Reyes, Benildo  (A)
Affiliations:	(A): University of Arkansas

AtSLT1 and NtSLT1 are involved in ion homeostasis and confer salt tolerance to yeast. They do not share sequence similarity with the small heat shock proteins but they have structural similarities at the molecular level, such as absence of introns and a heat shock protein domain. Unlike the small heat shock proteins, the slt1 is detected only in plants. We have reported here the cloning of OsSlt1, and another gene annotated as hypothetical protein but herein designated OsSlt2. This latter gene shares 61% similarity with OsSlt1, its transcript accumulates during drought and salt stresses, and it displays the same structural features as OsSlt1. Overexpression of OsSlt1 in E. coli confers thermo-tolerance to the bacterium. Phylogenetic analysis revealed that the two genes form distinct sub-families, and the phylogenetic tree can be used as a tool to classify the orthologs of OsSlt1 and OsSlt2 in other species. The evolution of the gene family did not follow the molecular clock, and the divergence of the two sub-families occurred after the divergence of monocots and dicots. The Slt are of hsp50-type, and are probably involved in molecular chaperone activities.