PLANT PHYSIOLOGY , Vol 115, Issue 4 1351-1358, Copyright © 1997 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Evidence That Heat and Ultraviolet Radiation Activate a Common Stress-Response Program in Plants That Is Alterd in the uvh6 Mutant of Arabidopsis thaliana
M. E. Jenkins, T. C. Suzuki and D. W. Mount
Departments of Molecular and Cellular Biology and Biochemistry, University of Arizona, Tucson, Arizona 85721
The uvh6 mutant of Arabidopsis was previously isolated in a screen for
increased sensitivity to ultraviolet (UV) radiation. uvh6 mutant plants
were killed by incubation at 37[deg]C for 4 d, a treatment not lethal to
wild-type plants. Furthermore, under permissive conditions, uvh6 plants
were yellow-green with an approximately one-third lower chlorophyll
content. Genetic analysis of the uvh6 mutant strongly suggested that all
three mutant phenotypes were due to mutation at the same genetic locus. To
understand UVH6 function more fully, the response of wild-type plants to
growth at elevated temperatures and exposure to UV radiation was analyzed.
Wild-type plants grown at 30[deg]C were as UV-hypersensitive and
yellow-green as uvh6 mutant plants grown at 24[deg]C. Mutant uvh6 plants
induced heat-shock protein HSP21 at a lower threshold temperature than
wild-type plants, indicating that the uvh6 mutant was exhibiting signs of
heat stress at a 4 to 5[deg]C lower temperature than wild-type plants. We
propose that UV damage and heat induce a common stress response in plants
that leads to tissue death and reduced chloroplast function, and that the
UVH6 product is a negative regulator of this response.
