Supression of phyB dark reversion by PCH1 and PCHL (Nature Comms.)

Nature Comms. Phytochromes can exist in two states: an inactive state Pr and an active state Pfr. They convert into each other by light absorption. They can also revert to the inactive state by a light-independent thermal relaxation process called dark reversion. Phytochrome B is the primary receptor for red light (R) and is strongly affected by dark reversion. Recently a new protein PCH1 (PHOTOPERIODIC CONTROL OF HYPOCOTIL 1) has been found to bind light-activated phyB. Enderle and collaborators found that a homologue PCHL (PCH1-LIKE) also bound to light activated phyB. The pch1 pchl double mutant shows an accerated phyB dark reversion. Experiments with pulses of R and FR with overexpressors of PCH1 and PCHL showed that the effect is specific for dark reversion and does not affect photoconversion. Overexpression of PCH1 and PCHL also strongly reduced phyB dark reversion as shown by measurements of phyB active and total levels. (Summary by Cecilia Vasquez-Robinet)  Nature Comms. 10.1038/s41467-017-02311-8