Gravitropic growth in roots

Plants detect the direction of gravity and regulate their growth to maintain shoots growing upwards and roots downwards. This directional growth response is called gravitropism. This movie shows the response of the root of mouse ear cress (Arabidopsis thaliana) to being laid ion its side. Cells at the top of the root elongate fatser than on the bottom and so lever the root tip down. Time lapsed over 2 hrs.

For more research into this response see:
Blancaflor and Masson (2013) Plant Physiology 133:1677-1690

Toyota and Gilroy (2013) American Journal of Botany 76: 648-660