Tonsor, Stephen , Brodsky, Jeffrey , Scott, Craig , Boumaza, Imene , Liss, Toby , Vierling, Elizabeth .
Heat shock protein expression variation among natural accessions of A. thaliana.
Heat shock proteins are crucial for acquired thermal tolerance, but natural variation in expression and its consequences are poorly understood. We quantified natural variation in Hsp101 expression in Arabidopsis thaliana under controlled environmental conditions, addressing four hypotheses: H1: Hsp101 expression affects fitness and the fitness effects depend on thermal environment. H2: The fitness effects of Hsp101 depend on genetic background. We addressed H1 and H2 by comparing lifetime fruit production for two standard genotypes, Columbia and Landsberg erecta, and their Hsp101 null mutants. Functional Hsp101 genes produced significantly more fruits than their knockouts, regardless of induction treatment or genetic background. The sign of the fitness effect was constant, but Col had a much stronger fitness response. H3: Hsp101 expression has pleiotropic effects on multiple traits. We examined Col, Ler and two additional wild-collected genotypes. Hsp101 functionality had a highly significant effect (MANOVA). Genetic background influenced the multivariate response to Hsp101 functionality and to the effects of exposure to 38C temperature. Hsp101 functionality decreased fruit production, days to germination and days to bolting; it increased transpiration rate, mass, and number of inflorescences. H4: Natural populations vary genetically in the temperature response of Hsp101 expression. 10 ‘ecotypes’ from www.arabidopsis.org differed significantly in Hsp101 expression response slopes across a 22C to 40C temperature gradient. The regression r2 = 72%. Hsp expression clearly evolves divergently among populations. Its study in relation to habitat characteristics would provide valuable insight as to the fitness tradeoffs in Hsp expression evolution.
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1 - University of Pittsburgh, Department of Biological Sciences, Langley Hall, Pittsburgh, Pennsylvania, 15260, USA
2 - University of Pittsburgh, Biological Sciences, Pittsburgh, PA, 15260, United States
4 - The University of Arizona, Biochemistry and Molecular Biophysics
Presentation Type: Oral Paper:Papers for Topics
Location: Williford C/Hilton
Date: Wednesday, July 11th, 2007
Time: 11:15 AM