Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2006
Publication Date: 11/24/2006
Citation: Uauy, C., Distelfeld, A., Fahima, T., Blechl, A.E., Dubcovsky, J. 2006. A NAC gene regulating senescence improves grain protein, zinc, and iron content in wheat. Science. 314(5803):1298-1301. Interpretive Summary: Wheat is a cereal crop grown in a number of temperate environments worldwide and its grain is processed into a variety of foods that are part of the cuisines of many cultures. The research in this paper was aimed at increasing the nutritional value of wheat by isolating and characterizing a wheat gene that had been associated with grain protein, Zn and Fe contents. Wild durum (pasta) wheat has shorter grain maturation periods and higher protein, zinc and iron contents than domesticated wheats due to the presence of this gene. The version of the gene found in a wild ancestor of durum wheat was isolated, sequenced and compared to the version in modern domesticated wheats. We found that the version in domesticated wheats was inactive, thus explaining their lower grain protein contents relative to the wild durum wheat. Thus, this research has identified a gene that can be used to improve the nutritional value of wheat grain. The active version can be incorporated by breeding or genetic engineering to increase the protein, zinc and iron contents of domesticated wheats, making them more nutritious. This will be especially valuable in regions of the world where malnourished people depend on wheat as a major source of calories in their diets.
Technical Abstract: Enhancing the nutritional value of food crops is a sensible strategy for improving human nutrition and health. We report here the positional cloning of Gpc-B1, a wheat QTL associated with increased grain protein, Zn and Fe contents. The ancestral wild wheat allele encodes a NAC transcription factor (TaNAM) that accelerates senescence and increases nutrient remobilization from leaves to developing grains, whereas modern cultivated wheat carries a non-functional TaNAM allele. Reduction in RNA levels of the multiple homologous copies of TaNAM by RNA interference delayed senescence by over 3 weeks and reduced wheat grain protein, Zn and Fe contents by over 30%.