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Pak. J. Bot., 47(6): 2269-2275, 2015.

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THE INTERACTIVE EFFECTS OF N SUPPLY AND TEMPERATURE ON PHOTOSYNTHESIS AND TRANSCRIPTION EXPRESSION OF RUBISCO AND ITS ACTIVASE GENES IN THE SEEDLINGS OF CAMELLIA OLEIFERA

BAOMING WANG¹, YONGZHONG CHEN^1*, XIAOFENG TAN², XIANGNAN WANG¹, LI MA¹, LONGSHENG CHEN¹, SHAOFENG PENG¹, RUI WANG¹ AND JIAN LUO¹

¹National Engineering Research Center of Oil-tea Camellia, Hunan Academy of Forestry, Changsha 410004, PR China

²The Key Lab. of Non-wood Forest Products of State Forestry Administration, Central South University of Forestry and Technology, Changsha, 410004, PR China

^*Corresponding author Email: chenyongzhong06@163.com; Tel: +86 731-85657615

Abstract: In this study, we assessed the interactive effects of nitrogen (N) gradients under different temperatures on the net photosynthetic rate (Pn),  intercellular CO₂ concentration (Ci), stomatal conductance (gs), transpiration rate (E) and in vivo velocity of Rubisco carboxylation (Vc) for 'Xianglin 14' seedlings of Camellia oleifera. We found that Pn was higher at the moderate N concentration than those at lower and higher N concentrations at 15°C and  20°C, and gs and E exhibited the same trend as Pn with exception of  Ci (due to the some reverse recorders), suggesting that the moderate N supply was more favorable for photosynthesis under 20°C. Furthermore, transcript patterns of Co-rbcL, Co-rbcS and Co-RCA presented similar tendencies as these photosynthetic parameters, while the redundant N down-regulated transcripts of these genes. In addition, these photosynthetic parameters and their corresponding molecular evidences displayed significant correlations, indicating that the transcript level of Co-RCA was a more optimal molecular marker to evaluate regulatory effects of N and temperature on seedlings than those of Co-rbcS and Co-rbcL. Collectively, our study quantified the relationships among temperature, N supply, photosynthetic parameters and the transcriptions of Rubisco related genes, and affirmed that physiological and molecular assays were sufficiently sensitive to resolve the interactive effects of N supply and temperature. Ultimately this allows optimization of management practices to improve the photosynthetic efficiency.

Key words: Camellia oleifera, Nitrogen, Temperature, Effect, Photosynthesis, Rubisco, Rubisco activase, Transcription.