A weak combined magnetic field changes root gravitropism

Although gravitropism has been studied for many decades, many questions on plant gravitropism, including the participation of Ca2+ ions in graviperception and signal transduction, remain open and require new experiments. We have studied gravistimulation and root gravitropism in the presence of the weak, alternating magnetic field that consisted of a sinusoidal frequency of 32 Hz inside a μ-metal shield. We discovered that this field changes normally positively gravitropic cress root to exhibit negative gravitropism. Because the combined magnetic field was adjusted to the cyclotron frequency of Ca2+ ions, the obtained data suggest that calcium ion participate in root gravitropism. Simultaneous application of the oscillating magnetic field of the same frequency ion induce oscillation of Ca2+ ions and can change the rate and/or the direction of Ca2+ ion flux in roots. Control and magnetic field-exposed roots were examined for change in the distribution of amyloplasts and cellular organelles by light, electron, and confocal laser microscopy.