Analysis of magnetic gradients to study gravitropism.

Karl H Hasenstein, Susan John, Peter Scherp, Daniel Povinelli, Susan Mopper

Biology Department, University of Louisiana at Lafayette, Lafayette, Louisiana 70504-2451, USA. hasenstein@louisiana.edu

American journal of botany 2013 Jan

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Gravitropism typically is generated by dense particles that respond to gravity. Experimental stimulation by high-gradient magnetic fields provides a new approach to selectively manipulate the gravisensing system. The movement of corn, wheat, and potato starch grains in suspension was examined with videomicroscopy during parabolic flights that generated 20 to 25 s of weightlessness. During weightlessness, a magnetic gradient was generated by inserting a wedge into a uniform, external magnetic field that caused repulsion of starch grains. The resultant velocity of movement was compared with the velocity of sedimentation under 1 g conditions. The high-gradient magnetic fields repelled the starch grains and generated a force of at least 0.6 g. Different wedge shapes significantly affected starch velocity and directionality of movement. Magnetic gradients are able to move diamagnetic compounds under weightless or microgravity conditions and serve as directional stimulus during seed germination in low-gravity environments. Further work can determine whether gravity sensing is based on force or contact between amyloplasts and statocyte membrane system.

Citation

Karl H Hasenstein, Susan John, Peter Scherp, Daniel Povinelli, Susan Mopper. Analysis of magnetic gradients to study gravitropism. American journal of botany. 2013 Jan;100(1):249-55