Abstract
Photosynthetic organisms experience wide fluctuations in light intensity and regulate light harvesting accordingly to prevent damage from excess energy. The antenna quenching component qH is a sustained form of energy dissipation that protects the photosynthetic apparatus under stress conditions. This photoprotective mechanism requires the plastid lipocalin LCNP and is prevented by SUPPRESSOR OF QUENCHING1 (SOQ1) under non-stress conditions. However, the molecular mechanism of qH relaxation has yet to be resolved. Here, we isolated and characterized RELAXATION OF QH1 (ROQH1), an atypical short-chain dehydrogenase–reductase that functions as a qH-relaxation factor in Arabidopsis. The ROQH1 gene belongs to the GreenCut2 inventory specific to photosynthetic organisms, and the ROQH1 protein localizes to the chloroplast stroma lamellae membrane. After a cold and high-light treatment, qH does not relax in roqh1 mutants and qH does not occur in leaves overexpressing ROQH1. When the soq1 and roqh1 mutations are combined, qH can neither be prevented nor relaxed and soq1 roqh1 displays constitutive qH and light-limited growth. We propose that LCNP and ROQH1 perform dosage-dependent, antagonistic functions to protect the photosynthetic apparatus and maintain light-harvesting efficiency in plants.
| Original language | English |
|---|---|
| Pages (from-to) | 154-166 |
| Number of pages | 13 |
| Journal | Nature Plants |
| Volume | 6 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 13 Feb 2020 |
Funding
We thank S. Ruzin and D. Schichnes from the Biological Imaging Facility and K. McDonald and R. Zalpuri from the Transmission Electron Microscopy Facility at University of California, Berkeley for technical advice and assistance; S. Shahrasbi and S. Lee for assistance with mutant screening and crosses; C. Marshall for advice regarding DNA sequencing; F. Ouellet for providing antibodies against LCNP; M. Iwai for advice regarding BN–PAGE and critical reading of the manuscript; and R. Croce and C. Gee for critical discussions. C.L.A. would like to thank Daniel L. Amstutz, who passed away during the writing of this manuscript, for guidance and support. This research was supported by the Division of Chemical Sciences, Geosciences and Biosciences, the Office of Basic Energy Sciences and the Office of Science, US Department of Energy (Field Work Proposal 449B). This work used the Vincent J. Coates Genomics Sequencing Laboratory at University of California, Berkeley, supported by National Institutes of Health S10 Instrumentation Grants S10RR029668 and S10RR027303. R.F. was supported by the Dutch Organization for Scientific Research via an ECHO grant to R. Croce and by the US Department of Energy Office of Science, Office of Biological and Environmental Research programme under award no. DE-FC02-02ER63421. A.S. was supported by the National Institutes of Health National Research Service Award Trainee appointment (grant no. GM007127). K.K.N. is an investigator of the Howard Hughes Medical Institute.
| Funders | Funder number |
|---|---|
| Dutch Organization for Scientific Research | |
| Office of Basic Energy Sciences | |
| Office of Biological and Environmental Research | |
| US Department of Energy | |
| US Department of Energy Office of Science | |
| National Institutes of Health | S10RR027303, S10RR029668 |
| Howard Hughes Medical Institute | |
| U.S. Department of Energy | FWP 449B |
| National Institute of General Medical Sciences | T32GM007127 |
| Office of Science | |
| Chemical Sciences, Geosciences, and Biosciences Division |
