Photoactivated CRY1 and phyB interact directly with AUX/IAA proteins to inhibit auxin signaling in Arabidopsis (OA)

So far we know that light inhibits hypocotyl cell elongation and that the master regulatory plant hormone auxin induces hypocotyl elongation. Light signal depends on cryptochrome (CRY1) and phytochrome (PhyB). Auxin signal follows the traditional TIR1/AFB receptor-mediated degradation of AUX/IAA repressor. In this article, they have figured out the underlying molecular mechanism for hypocotyl growth and convergence point of light and auxin signaling for that purpose. In the absence of light, CRY1 stays in the inactive form and phyB remains in the cytosol, while in the presence of light CRY1 becomes active and phyB moves from cytoplasm to nucleus. In this case, they bind the repressor of auxin signaling pathway, AUX/IAA, and stabilize it. As a result, auxin signaling is stopped and cannot promote hypocotyl elongation. (Summary by Arif Ashraf – @aribidopsis) Molecular Plant 10.1016/j.molp.2017.12.003