The research lab led by Dr. Yang Jianping at Institute of Crop Sciences (ICS), CAAS confirmed that PHYTOCHROME RAPIDLY REGULATED 1 (PAR1) and PAR2 redundantly enhance seedling de-etiolation in multiple photoreceptor signaling pathways (Figure A); transcript abundances of PAR1 and PAR2 are repressed by phytochrome A (phyA), phyB, and cryptochrome 1 (CRY1) under Far-red (FR), Red (R), and blue (B) light conditions, respectively. Both PAR1 and PAR2 act downstream of the photomorphogenic repressor CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), and COP1 mediates the degradation of PAR1 and PAR2 through the 26S proteasome pathway (Figure A- Figure E).

The work further showed that both PAR1 and PAR2 act in a separate pathway from ELONGATED HYPOCOTYL5 (HY5) and LONG HYPOCOTYL IN FAR-RED1 (HFR1) under different light conditions, except for sharing in the same pathway with HFR1 under FR light (Figure F). Together, the results substantiate that PAR1 and PAR2 are positive factors functioning in multiple photoreceptor signaling pathways during seedling de-etiolation (Figure F).

Supported by Genetically Modified Organisms Breeding Major Projects and National Natural Science Foundation of China, the study enriches the knowledge and understanding of PAR1 and PAR2 in the study of light signal transduction.

On December 12, 2013, the research was published online on the international mainstream journal Plant Physiology.