Todd, Sadie , Galen, Candace .
Going underground: roots track blue light gradients in the soil.
Due to their sessile nature, plants have evolved different ways to effectively exploit their habitats. One important way that plants continuously modify their structure to maximize their nutrient, sunlight and water intake is through photomorphogenesis. Most work on light-cued changes in plant growth and form focus on leaves and stems. However, we tested the hypothesis that roots respond to heterogeneous soil conditions by sensing light gradients. Specifically, we examined the response of Arabadopsis thaliana roots to a light gradient by manipulating light in soil independent of other factors using either water-saturated or completely dry packages of top soil as filters placed outside of clear, soil filled planting boxes. We tested the response of five genotypes: a wild-type control and four mutants: two hyper-phototropic mutants, and phot1 and phot2 null mutants. We measured total root length on opposite sides of the planting box bordered by the “wet” vs. “dry” filters. We found significant differences among genotypes in the distribution of root length: loss of the functional phot1 gene resulted in more random distribution of roots. All genotypes with functional phot1 concentrated their root growth toward the wet (dark) soil filter. Additionally, the phot1 null genotype tended to produce more total root length than other genotypes, suggesting that higher blue light intensity in the soil acted to inhibit root growth, as predicted from laboratory studies of root phototropism.
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1 - University of Missouri - Columbia, Biological Sciences, 216 Tucker Hall, Columbia, MO, 65201, USA
2 - University of Missouri-Columbia, Division of Biological Science, 217 Tucker Hall, Columbia, Missouri, 65211, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM