Transcription Factor TaDof1 Improves Nitrogen and Carbon Assimilation Under Low-Nitrogen Conditions in Wheat

Abstract

A single transcription factor is known to coordinate expression of a set of metabolites in a biochemical pathway; its use therefore can be a functional strategy in generating plants with desired traits. Triticum aestivum Dof1 (TaDof1) transcription factor is mainly associated with improved nitrogen assimilation in plants. In the current research, the transgenic wheat overexpressing TaDof1 transcription factor, under a constitutive promoter, was developed by Agrobacterium-mediated transformation. The two elite wheat cultivars (Galaxy and Faisalabad-2008) were selected for transformation study. The T0 plants were subjected to screening using selection medium containing herbicide BASTA. PCR results confirmed that only 8 out of 31 plants possessed the complete TaDof1 cassette. A transformation efficiency of 0.46% for Galaxy and 0.08% for Faisalaad-2008 was obtained. The quantitative RT-PCR was performed on T1 plants grown under nitrogen-limiting conditions. A substantial rise in the expression of citrate synthase (CS), isocitrate dehydrogenase (ICDH), phosphoenolpyruvate carboxylase (PEPC), and pyruvate kinase (PK) genes regulated by TaDof1 was observed after 4 weeks of nitrogen stress in T1 plants. The maximum fold increase of 464 was recorded for ICDH. Our findings indicate a cooperative modification of nitrogen and carbon metabolisms since they are intimately linked together. Overexpression of TaDof1 in wheat resulted in a significant increase in various agronomic traits. Furthermore, various physiological and biochemical markers (chlorophyll, protein, and soluble sugar contents) exhibited a profound change in TaDof1 transgenic plants in comparison with wild type plants. The results clearly depict the merits of employing transcription factors in engineering plant metabolisms.