Multi-year field evaluation of nicotianamine biofortified bread wheat

Authors: BEASELY, JESSE - University Of Melbourne; BONNEAU, JULIEN - University Of Melbourne; MORENO-MOYANO, LAURA - University Of Melbourne; CALLAHAN, DAMIEN - Deakin University; HOWELL, KATE - University Of Melbourne; TAKO, ELAD - Cornell University; TAYLOR, JULIAN - Adelaide University; Glahn, Raymond; APPELS, RUDI - University Of Melbourne; JOHNSON, ALEXANDER - University Of Melbourne

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2021
Publication Date: 12/13/2021
Citation: Beasely, J.T., Bonneau, J.P., Moreno-Moyano, L.T., Callahan, D.L., Howell, K.S., Tako, E., Taylor, J., Glahn, R.P., Appels, R., Johnson, A.A. 2021. Multi-year field evaluation of nicotianamine biofortified bread wheat. Plant Journal. 109:1168-1182. https://doi.org/10.1111/tpj.15623.
DOI: https://doi.org/10.1111/tpj.15623

Interpretive Summary: Conventional breeding efforts for iron (Fe) and zinc (Zn) concentration of bread wheat have been hindered by a lack of genetic variation for these traits, and the fact that lower concentrations of Fe and Zn results in lower grain yield. We have employed genetic engineering to increase biosynthesis of compounds, nicotianamine (NA) and 2-deoxymugineic acid (DMA) in bread wheat. This approach resulted in increased Fe and Zn concentrations in wholemeal and white flour. In this study we describe multi-location field trial evaluation of this approach over 3 harvest 'years. Overall, the results demonstrate higher concentrations of NA, DMA, Fe, and Zn in wholemeal flour, white flour, and white bread; and higher Fe bioavailability white flour relative to a control. Multi-environment models of agronomic and grain nutrition traits revealed a negative correlation between grain yield and grain Fe, Zn, and total protein concentrations, yet no correlation between grain yield and grain NA and DMA concentrations. White flour Fe bioavailability was positively correlated with white flour NA concentration, suggesting that NA-chelated Fe should be targeted in wheat Fe biofortification efforts.

Technical Abstract: Conventional breeding efforts for iron (Fe) and zinc (Zn) biofortification of bread wheat (Triticum aestivum L.) have been hindered by a lack of genetic variation for these traits and a negative correlation between grain Fe and Zn concentrations and yield. We have employed genetic engineering to constitutively express (CE) the rice (Oryza sativa) nicotianamine synthase 2 (OsNAS2) gene and upregulate biosynthesis of two metal chelators – nicotianamine (NA) and 2'-deoxymugineic acid (DMA) – in bread wheat, resulting in increased Fe and Zn concentrations in wholemeal and white flour. Here we describe multi-location confined field trial (CFT) evaluation of a low-copy transgenic CE-OsNAS2 wheat event (CE-1) over 3'years and demonstrate higher concentrations of NA, DMA, Fe, and Zn in CE-1 wholemeal flour, white flour, and white bread and higher Fe bioavailability in CE-1 white flour relative to a null segregant (NS) control. Multi-environment models of agronomic and grain nutrition traits revealed a negative correlation between grain yield and grain Fe, Zn, and total protein concentrations, yet no correlation between grain yield and grain NA and DMA concentrations. White flour Fe bioavailability was positively correlated with white flour NA concentration, suggesting that NA-chelated Fe should be targeted in wheat Fe biofortification efforts.