Gravity Sensing for Gravitropism

Gravitropism allows plants to reorient their growth along the gravity vector by sensing and responding to changes in orientation. This review summarizes recent advances in elucidating the molecular mechanisms underlying gravity sensing and signal transduction, with a focus on flowering plants. Central to this process are starch-filled amyloplasts that sediment within statocytes and activate downstream signaling pathways. Recent discoveries include the identification of LAZY1-LIKE family proteins, which translocate from amyloplasts to the plasma membrane in response to gravistimulation and recruit regulators such as RLDs and D6PKs to control polar auxin transport. We also discuss the emerging concept of antigravitropic offset, which modulates lateral organ angles, and its potential mechanistic divergence from classical gravitropism. Collectively, these findings reveal an integrated system to regulate organ orientation and plant architecture.