Abstract
The phototropic response of Arabidopsis thaliana seedlings is initiated by the blue-light photoreceptors, phototropins (phot1 and phot2), and by their signal transducers, NPH3 and RPT2. NPH3 and RPT2 interact with phot1 respectively. RPT2 mRNA levels are induced by irradiation with either blue light or red light in a fluence rate-dependent manner, RPT2 play a role in the phot1 signaling pathway. However, the regulations of RPT2 expression remain unclear. Here, we report that expression of RPT2 mRNA was regulated by phyA, phyB cry1, and cry2 redundantly, and that phyA, cry1, and cry2 play important roles in the phototropic response. We also demonstrated possibility that phot1 induces the expression of RPT2 in seedlings under blue light conditions through translational regulation. These results suggested that expression level of RPT2 was regulated through multiple stages by photoropin, phytochrome and cryptochrome, and that every photoreceptors signal converges on the RPT2.
