Cryptochrome 2 and phototropin 2 regulate resistance protein-mediated viral defense by negatively regulating an E3 ubiquitin ligase

• Published in: Proceedings of the National Academy of Sciences - PNAS 2010-07, Vol.107 (30), p.13538-13543
• Main Authors: Jeong, Rae-Dong, Chandra-Shekara, A. C., Barman, Subhankar Roy, Navarre, Duroy, Klessig, Daniel F., Kachroo, Aardra, Kachroo, Pradeep, Jones, Jonathan Dallas
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - virology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Binding sites; Biological Sciences; Carmovirus - physiology; Cell membranes; Cryptochromes; Cryptochromes - genetics; Cryptochromes - metabolism; Disease resistance; Flowers & plants; Gene expression; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant; Genetic mutation; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Host-Pathogen Interactions; Immunity, Innate - radiation effects; Immunoblotting; Inoculation; Leaves; Light; Light effects; Microscopy, Confocal; Mutation; Perception; Phenotypes; Photoreceptors; Plant cells; Plant diseases; Plant Diseases - genetics; Plant Diseases - virology; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Leaves - virology; Plant resistance; Plants; Plants, Genetically Modified; proteasome inhibitors; Protein Binding; Proteins; R protein; Repressor Proteins - genetics; Repressor Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Salicylic Acid - metabolism; Signal Transduction; Survival; Turnip crinkle virus; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1004529107

Light harvested by plants is essential for the survival of most life forms. This light perception ability requires the activities of proteins termed photoreceptors. We report a function for photoreceptors in mediating resistance (R) protein-derived plant defense. The blue-light photoreceptors, cryptochrome (CRY) 2 and phototropin (PHOT) 2, are required for the stability of the R protein HRT, and thereby resistance to Turnip Crinkle virus (TCV). Exposure to darkness or blue-light induces degradation of CRY2, and in turn HRT, resulting in susceptibility. Overexpression of HRT can compensate for the absence of PHOT2 but not CRY2. HRT does not directly associate with either CRY2 or PHOT2 but does bind the CRY2-/PHOT2-interacting E3 ubiquitin ligase, COP1. Application of the proteasome inhibitor, MG132, prevents blue-light-dependent degradation of HRT, consequently these plants show resistance to TCV under blue-light. We propose that CRY2/PHOT2 negatively regulate the proteasome-mediated degradation of HRT, likely via COP1, and blue-light relieves this repression resulting in HRT degradation.