J Integr Plant Biol. ›› 2015, Vol. 57 ›› Issue (5): 468-476.DOI: 10.1111/jipb.12241

Special Issue: Abiotic Stresses

• Molecular Physiology • Previous Articles     Next Articles

Regulation of pepc gene expression in Anabaena sp. PCC 7120 and its effects on cyclic electron flow around photosystem I and tolerances to environmental stresses

Xiao-Hui Jia1, Peng-Peng Zhang2, Ding-Ji Shi1,3*, Hua-Ling Mi4, Jia-Cheng Zhu1, Xi-Wen Huang1 and Pei-Min He1*   

  1. 1Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education Shanghai, Shanghai, China
    2Department of Biological Sciences, Louisiana State University, LA, USA
    3Institute of Botany, the Chinese Academy of Sciences, Beijing, China
    4National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai, China

Abstract:

Since pepc gene encoding phosphoenolpyruvate carboxylase (PEPCase) has been cloned from Anabaena sp. PCC 7120 and other cyanobacteria, the effects of pepc gene expression on photosynthesis have not been reported yet. In this study, we constructed mutants containing either upregulated (forward) or downregulated (reverse) pepc gene in Anabaena sp. PCC 7120. Results from real-time quantitative polymerase chain reaction (RT-qPCR), Western blot and enzymatic analysis showed that PEPCase activity was significantly reduced in the reverse mutant compared with the wild type, and that of the forward mutant was obviously increased. Interestingly, the net photosynthesis in both the reverse mutant and the forward mutant were higher than that of the wild type, but dark respiration was decreased only in the reverse mutant. The absorbance changes of P700 upon saturation pulse showed the photosystem I (PSI) activity was inhibited, as reflected by Y(I), and Y(NA) was elevated, and dark reduction of P700+ was stimulated, indicating enhanced cyclic electron flow (CEF) around PSI in the reverse mutant. Additionally, the reverse mutant photosynthesis was higher than that of the wild type in low temperature, low and high pH, and high salinity, and this implies increased tolerance in the reverse mutant through downregulated pepc gene.

 

 

Jia XH, Zhang PP, Shi DJ, Mi HL, Zhu JC, Huang XW, He PM (2015) Regulation of pepc gene expression in Anabaena sp. PCC 7120 and its effects on cyclic electron flow around photosystem I and tolerances to environmental stresses. J Integr Plant Biol 57: 468–476. doi: 10.1111/jipb.12241

Key words: Anabaena sp. PCC 7120, cyclic electron flow, pepc gene, photosynthesis, tolerance

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