title: Transcriptional and post-translational control of chlorophyll biosynthesis by dark-operative protochlorophyllide oxidoreductase in Norway spruce.
abstract: Unlike angiosperms, gymnosperms use two different enzymes for the reduction of protochlorophyllide to chlorophyllide: the light-dependent protochlorophyllide oxidoreductase (LPOR) and the dark-operative protochlorophyllide oxidoreductase (DPOR). In this study, we examined the specific role of both enzymes for chlorophyll synthesis in response to different light/dark and temperature conditions at different developmental stages (cotyledons and needles) of Norway spruce (Picea abies Karst.). The accumulation of chlorophyll and chlorophyll-binding proteins strongly decreased during dark growth in secondary needles at room temperature as well as in cotyledons at low temperature (7 °C) indicating suppression of DPOR activity. The levels of the three DPOR subunits ChlL, ChlN, and ChlB and the transcripts of their encoding genes were diminished in dark-grown secondary needles. The low temperature had minor effects on the transcription and translation of these genes in cotyledons, which is suggestive for post-translational control in chlorophyll biosynthesis. Taking into account the higher solubility of oxygen at low temperature and oxygen sensitivity of DPOR, we mimicked low-temperature condition by the exposure of seedlings to higher oxygen content (33%). The treatment resulted in an etiolated phenotype of dark-grown seedlings, confirming an oxygen-dependent control of DPOR activity in spruce cotyledons. Moreover, light-dependent suppression of mRNA and protein level of DPOR subunits indicates that more efficiently operating LPOR takes over the DPOR function under light conditions, especially in secondary needles.
authors.affiliation: Faculty of Science, Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic.
authors.forename: Tibor
authors.initials: T
authors.lastname: Stolárik
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt-University Berlin, Philippstrasse13, Building 12, 10115, Berlin, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Hedtke
authors.affiliation: Faculty of Science, Department of Experimental Plant Biology, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Šantrůček
authors.affiliation: Faculty of Science, Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Ilík
authors.affiliation: Institute of Biology/Plant Physiology, Humboldt-University Berlin, Philippstrasse13, Building 12, 10115, Berlin, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
authors.affiliation: Faculty of Science, Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic. andrej.pavlovic@upol.cz.
authors.forename: Andrej
authors.initials: A
authors.lastname: Pavlovič
mesh_terms: D002734:Chlorophyll / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008027:Light; D009664:Norway; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000096:biosynthesis* / Q000378:metabolism*; D028222:Picea / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D002734:Chlorophyll; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase
keywords: Chill stress; Chlorophyll; DPOR; Low temperature; Norway spruce; Protochlorophyllide