Evol Ecol Res 1: 731-751 (1999)     Full PDF if your library subscribes.

Light-sensitive plasticity genes in Arabidopsis thaliana: Mutant analysis and ecological genetics

Hilary S. Callahan,* Carolyn L. Wells and Massimo Pigliucci

Department of Botany, University of Tennessee, Knoxville, TN 37996-1100, USA

Hilary Callahan, Department of Biological Sciences, Barnard College, 3009 Broadway, New York, NY 10027, USA.
e-mail: hcallahan@barnard.edu


To explore how altered plasticity genes affect whole-plant phenotypes and plant fecundity, we conducted an experiment with isogenic lines of Arabidopsis thaliana, representing a wild type and seven photomorphogenic mutants. We exposed all genotypes to a 3 × 3 factorial array of light intensity and water availability. We documented altered plasticity to light intensity not only for mutants insensitive to blue wavelengths, but also for mutants insensitive to red and far-red wavelengths. Our results are consistent with models of co-action between these two distinct photoreceptory systems. Photomorphogenic mutants showed altered plasticity to light intensity not only for seedling and rosette morphology, but also for the duration of the vegetative and reproductive phases. Fruit production and two other performance traits showed no significant variation for plasticity to light intensity, but the means of all three performance traits differed significantly among genotypes. Notably, mean fruit production was much lower in the wild type than in the blue-insensitive and far-red insensitive mutants. The high fruit production of these mutants declined with decreasing water availability. In contrast, the low fruit production of the wild type was quite stable with declining water. However, we found only marginally significant variation among genotypes for the water-mediated plasticity of fruit production. Our comparisons of photomorphogenic mutants and wild-type plants suggest that there may be significant costs associated with the photoreceptory systems. However, the enhanced fitness of mutant genotypes may not be realizable in natural conditions, where very low water availability or curtailed growing seasons may be common.

Keywords: cryptochrome, epistasis, flowering time, life-history evolution, phenotypic plasticity, photomorphogenesis.

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        © 1999 Hilary S. Callahan. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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