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United States Department of Agriculture

Agricultural Research Service

Research Project: AN INTEGRATED DATABASE AND BIOINFORMATICS RESOURCE FOR SMALL GRAINS

Location: Genomics and Gene Discovery

Title: Structural analysis of the wheat genes encoding NADH-dependent glutamine-2-oxoglutarate amidotransferases genes and correlation with grain protein content

Authors
item Nigro, Domenica -
item Gu, Yong
item Huo, Naxin -
item Marcotuli, Illaria -
item Blanco, Antonio -
item Gadaleta, Agata -
item Anderson, Olin

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 23, 2013
Publication Date: September 17, 2013
Citation: Nigro, D., Gu, Y.Q., Huo, N., Marcotuli, I., Blanco, A., Gadaleta, A., Anderson, O.D. 2013. Structural analysis of the wheat genes encoding NADH-dependent glutamine-2-oxoglutarate amidotransferases genes and correlation with grain protein content. PLoS One. 8(9):e73751. doi:10.1371/journal.pone.0073751.

Interpretive Summary: Nitrogen uptake and metabolism are essential elements in attempts to breed improved cereal cultivars for grain or silage production. One of the enzymes related to nitrogen metabolism is glutamine-2-oxoglutarate amidotransferase (GOGAT). Together with glutamine synthetase (GS), GOGAT maintains the flow of nitrogen from NH4+ into glutamine and glutamate, and these enzymes regulate essential metabolic functions including essential amino acid synthesis. The purpose of the present work was to identify and analyze the structure of wheat GOGAT genes, and to study the expression in two durum wheat cultivars characterized by low and high kernel protein content. The gene sequences were successfully obtained for both bread wheat (Triticum aestivum) and pasta wheat (Triticum turgidum). The results of this work can be applied to understanding more on how to increase wheat grain protein content, make the most efficient use of fertilizers for sustainable agriculture, and contribute to basic research in wheat physiology and biochemistry.

Technical Abstract: Nitrogen uptake and the efficient absorption and metabolism of nitrogen are essential elements in attempts to breed improved cereal cultivars for grain or silage production. One of the enzymes related to nitrogen metabolism is glutamine-2-oxoglutarate amidotransferase (GOGAT). Together with glutamine synthetase (GS), GOGAT maintains the flow of nitrogen from NH4+ into glutamine and glutamate, which are then used for several aminotransferase reactions during amino acid synthesis. The aim of the present work was to identify and analyze the structure of wheat NADH-GOGAT genomic sequences, and study the expression in two durum wheat cultivars characterized by low and high kernel protein content. The genomic sequences of the three homoeologous A, B and D NADH-GOGAT genes were obtained for hexaploid Triticum aestivum and the tetraploid A and B genes of Triticum turgidum ssp. durum. Analysis of the gene sequences indicates that all wheat NADH-GOGAT genes are composed of 22 exons and 21 introns. A comparative analysis of sequences among di- and mono-cotyledonous plants shows both regions of high conservation and of divergence. qRT-PCR performed with the two durum wheat cvs Svevo and Ciccio (characterized by high and low protein content, respectively) indicates different expression levels of the two NADH-GOGAT-3A and NADH-GOGAT-3B genes. The three hexaploid wheat homoeologous NADH-GOGAT gene sequences are highly conserved – consistent with the key metabolic role of this gene. However, the dicot and monocot amino acid sequences show distinctive patterns. Higher expression levels of NADH-GOGAT are associated with higher grain protein content in two durum wheats.

Last Modified: 4/25/2014
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