Dr. Margaret Ahmad
Pennsylvania State University
Delaware County Campus, Media, PA

Monday, February 19, 2007
3:00 pm (CT)
3269 Beckman Institute

Abstract

Cryptochromes are blue-light absorbing photoreceptors found in many organisms where they have been implicated in numerous growth, developmental, and circadian responses. In Arabidopsis thaliana, two cryptochromes, cry1 and cry2, mediate several blue-light dependent responses including hypocotyl growth inhibition. An increase in the intensity of the ambient magnetic field from 44 microTesla to 500 microTesla enhanced growth inhibition in Arabidopsis thaliana under blue light, when cryptochrome is the mediating pigment, but not under red light or in total darkness. Hypocotyl growth of Arabidopsis mutants lacking cryptochromes was unaffected by the increase in magnetic intensity. Additional cryptochrome-dependent responses, such as blue-light dependent anthocyanin accumulation and blue-light dependent degradation of cry2 protein, were also enhanced at the higher magnetic intensity. These findings show that higher plants are sensitive to the magnetic field in responses that are linked to cryptochrome-dependent signaling pathways. A crucial role for cryptochromes has recently been suggested in the magnetic compass of birds, providing the possibility of an intriguing parallel in the mechanisms mediating magnetic sensitivity in both animals and plants.