It is generally thought that sedimenting plastids are responsible for gravity sensing in higher plants. We directly tested the model generated by the current statolith hypothesis that the gravity sensing that leads to gravitropism results from an interaction between the plastids and actin microfilaments. We find that the primary roots of rice, corn, and cress undergo normal gravitropism and growth even when exposed to cytochalasin D, a disruptor of actin microfilaments. These results indicate that an interaction between amyloplasts and the actin cytoskeleton is not critical for gravity sensing in higher plants and weaken the current statolith hypothesis.

Cytochalasin D does not inhibit gravitropism in roots of rice, corn, and cress, challenging the current statolith hypothesis that gravity sensing in plants involves an interaction between plastids and actin microfilaments.

Cytochalasin D does not inhibit gravitropism in roots.

Key Takeaway: Cytochalasin D does not inhibit gravitropism in roots of rice, corn, and cress, challenging the current statolith hypothesis that gravity sensing in plants involves an interaction between plastids and actin microfilaments.