Recent Topics Posters
Youngstrom, Sarah , Galen, Candace , Liscum, Emmanuel .
Going Underground: Benefits of phototropism in Arabidopsis depend on the soil environment..
Phototropins are blue-light photoreceptors that control shoot and root phototropism in Arabidopsis thaliana. Here, we test the hypothesis that root phototropism confers a growth advantage under drought. In the greenhouse, seeds of two non-phototropic mutants (phot 1,nph3) and wild type A. thaliana were planted into soil varying from 26%-65% (w/w) water content. Rosette diameter was measured after three weeks growth. Wild type plants were significantly larger than non-phototropic plants, but the size advantage depended on soil moisture. Wild type plants had a 20% size advantage in dry soil (P<0.0001), and only a 12% advantage in wet soil (P<0.01). Results suggest that root phototropism enhances growth under drought. To explore causes of the wild type advantage under drought, we asked whether plants with impaired phototropism have less efficient root phenotypes than wild type plants. Seeds of the three genotypes were planted along the sides of clear plastic boxes, enabling us to track the roots. Light penetrated the soil only from the open top of the box; sides were wrapped to prevent illumination. One month later, boxes were unwrapped and roots traced. Though shoots of wild type and mutant plants were similar in size, wild type roots grew significantly longer, branched at narrower angles, and moved further through the soil than non-phototropic mutant roots. Pooled across all genotypes, root length was strongly correlated with shoot size under dry but not wet conditions. Genotype specific rooting profiles may explain why phototropism has a significant impact on growth and fitness of A. thaliana.
1 - University of Missouri-Columbia, Biological Sciences, 105 Tucker Hall, Columbia, Missouri, 65211, USA
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM