title: Photoinhibition of photosystem I at chilling temperature and subsequent recovery in Arabidopsis thaliana.
abstract: Chilling-induced photoinhibition and subsequent recovery was studied in Arabidopsis thaliana exposed to 4 degrees C and 150 micromol photons m(-2) s(-1). PSII showed progressive damage with a 14% decrease in quantum yield after 8 h exposure. In contrast, the damage to PSI leveled off after 8 h with a decrease in in vitro NADP+ photoreduction activity of around 32%. In vivo P700 measurements demonstrated that antenna efficiency was decreased by the photoinhibitory treatment. Measurements of P700 and immunoblotting demonstrated that the damaged PSI was not degraded during the 8 h light-chilling treatment, but after 12 h recovery at 20 degrees C, no damaged PSI remained in the thylakoids. Thus, degradation of damaged PSI is a step in the recovery and not a direct result of photodamage. Unlike photodamaged PSII, the PSI core complex is not repaired but completely degraded. In contrast, light harvesting complex I proteins have a slow turnover. PSII recovered completely within 8 h after transfer to 20 degrees C whereas PSI activity recovered very slowly, and the amount of PSI on a leaf area basis remained low even after 1 week at 20 degrees C. The results show that damage, protein turnover and recovery are well separated processes in Arabidopsis.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology, Royal Veterinary and Agricultural University, 40 Thorvaldsensvej, DK-1871 Frederiksberg C, Denmark.
authors.forename: Suping
authors.initials: S
authors.lastname: Zhang
authors.forename: Henrik Vibe
authors.initials: HV
authors.lastname: Scheller
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D003080:Cold Temperature; D015151:Immunoblotting; D008027:Light; D045331:Photosystem I Protein Complex / Q000378:metabolism / Q000528:radiation effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism / Q000528:radiation effects; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D020127:Recovery of Function
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; C001785:chlorophyll P 700