Transcriptional and post-translational control of chlorophyll biosynthesis by dark-operative protochlorophyllide oxidoreductase in Norway spruce

• Published in: Photosynthesis research Vol. 132; no. 2; pp. 165 - 179
• Main Authors: Stolárik, Tibor, Hedtke, Boris, Šantrůček, Jiří, Ilík, Petr, Grimm, Bernhard, Pavlovič, Andrej
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.05.2017; Springer; Springer Nature B.V
• Subjects: Biochemistry; Biomedical and Life Sciences; Chlorophyll; Chlorophyll - genetics; Chlorophyll - metabolism; Enzymes; Gene Expression Regulation, Plant; Genetic aspects; Life Sciences; Light; Norway; Original Article; Oxidoreductases Acting on CH-CH Group Donors - biosynthesis; Oxidoreductases Acting on CH-CH Group Donors - metabolism; Photosynthesis; Picea - enzymology; Picea - genetics; Picea - metabolism; Picea abies; Plant Genetics and Genomics; Plant Physiology; Plant Sciences; Protein binding; RNA; Temperature; Transcription (Genetics); Translation (Genetics); Trees; Chill stress; Protochlorophyllide; Chlorophyll; Norway spruce; DPOR; Low temperature
• ISSN: 0166-8595; 1573-5079
• DOI: 10.1007/s11120-017-0354-2

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.