Physiological Analysis of Phototropic Responses in Arabidopsis

Plants utilize light as sole energy source. To maximize light capture they are able to detect the light direction and orient themselves towards the light source. This phototropic response is mediated by the plant blue light photoreceptors phototropin1 and 2 (phot1 and phot2). Although fully differentiated plants also exhibit this response it can be best observed in etiolated seedlings. Differences in light between the illuminated and shaded site of a seedling stem lead to changes in the auxin-distribution, resulting in cell elongation on the shaded site. Since phototropism connects light perception, signaling, and auxin transport, it is of great interest to analyze this response with a fast and simple method.Here we describe a method to analyze the phototropic response of Arabidopsis seedlings. With numerous mutants available, its fast germination and its small size Arabidopsis is well suited for this analysis. Different genotypes can be simultaneously probed in less than a week.