Introduction of the ZmDof1 gene into rice enhances carbon and nitrogen assimilation under low-nitrogen conditions

Kurai, Tomohiro and Wakayama, Masataka and Abiko, Tomomi and Yanagisawa, Shuichi and Aoki, Naohiro and Ohsugi, Ryu (2011) Introduction of the ZmDof1 gene into rice enhances carbon and nitrogen assimilation under low-nitrogen conditions. Plant Biotechnology Journal, 9 (8). pp. 826-837. ISSN 1467-7652

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The excessive application of nitrogen fertilizer to maximize crop yields causes negative environmental effects such as pollution and ecological imbalance. To overcome this problem, researchers have attempted to improve the nitrogen assimilation capacity of crops. Maize Dof1 (ZmDof1) is a plant-specific transcription factor shown to promote nitrogen assimilation in Arabidopsis thaliana (Arabidopsis) even under nitrogen-deficient conditions. The present study examines the effect of the introduction of the ZmDof1 gene on carbon and nitrogen assimilation in rice. ZmDof1 induced the expression of phosphoenolpyruvate carboxylase (PEPC) genes in transgenic rice plants and transactivated the PEPC promoters in protoplast transient assays, showing similar effects in rice as in Arabidopsis. Transgenic rice expressing ZmDof1 and grown in the presence of 360 μm (nitrogen-sufficient) or 90 μm (nitrogen-deficient) of nitrogen concentrations showed modulation of metabolite content and gene expression associated with the anaplerotic pathway for the TCA cycle, suggesting an increased carbon flow towards nitrogen assimilation. Furthermore, increases in carbon and nitrogen amounts per seedling were found in Dof1 rice grown under nitrogen-deficient conditions. Nitrogen deficiency also resulted in the predominant distribution of nitrogen to roots, accompanied by significant increases in root biomass and modification of the shoot-to-root ratio. Measurement of the CO2 gas exchange rate showed a significant increase in the net photosynthesis rate in Dof1 rice under nitrogen-deficient conditions. Taken these together, the present study displayed that ZmDof1 expression in rice could induce gene expressions such as PEPC genes, modulate carbon and nitrogen metabolites, increase nitrogen assimilation and enhance growth under low-nitrogen conditions.

Item Type: Article
Uncontrolled Keywords: anaplerotic pathway;carbon assimilation;Dof1;nitrogen assimilation;Oryza sativa L.;phosphoenolpyruvate carboxylase
Subjects: Others > Fertilizer Applications
Depositing User: Mr Siva Shankar
Date Deposited: 13 Feb 2012 08:01
Last Modified: 16 Sep 2013 07:35
Official URL:
Acknowledgement: The authors thank Dr. Peter Quail for kindly providing the maize ubiquitin promoter. We also thank Dr. Seiichi Toki and Ms. Haruko Onodera for helpful advice on plant transformation. This work was supported by the Program for Promotion of Basic Research Activities for Innovative Biosciences (PROBRAIN).
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