TY - JOUR
T1 - A two-gene strategy increases iron and zinc concentrations in wheat flour, improving mineral bioaccessibility
AU - Harrington, Sophie A.
AU - Connorton, James M.
AU - Nyangoma, Natasha I.M.
AU - McNelly, Rose
AU - Morgan, Yvie M.L.
AU - Aslam, Mohamad F.
AU - Sharp, Paul A.
AU - Johnson, Alexander A.T.
AU - Uauy, Cristobal
AU - Balk, Janneke
N1 - Funding Information:
We would like to thank Sadiye Hayta, Mark Smedley, and Wendy Harwood (John Innes Centre, JIC) for wheat transformation; Julien P. Bonneau for growth of Gladius transformants; JIC Horticulture staff for plant growth; Alison Lovegrove (Rothamsted Research) for roller milling; Marina Franceschetti (JIC) for ICP-OES; Martin Rejzek (JIC Chemistry Platform) for synthesis of nicotinoyl-L-lysine; Ana Álvarez-Fernández (Spanish National Research Council, CSIC) for advice on NA quantification; Lionel Hill (JIC Metabolomics Platform) for assistance with LC–MS; Kirstie Halsey (Rothamsted Research) for sample preparation for microscopy; Shailender Verma for iron staining of TaVIT2 sections; Eva Wegel (JIC Bio-imaging Platform) for microscopy training and assistance. This work was supported by the Biotechnology and Biological Sciences Research Council, grant awards BB/ P019072/1 to J.M.C., M.F.A., P.A.S., C.U., and J.B. and BB/ T004363/1 to S.A.H., C.U. and J.B.; funding from HarvestPlus to N.I.M.N. and A.A.T.J.; a studentship from the John Innes Foundation to R.M. and a Wellcome Trust studentship to Y.M.L.M.
Funding Information:
This work was supported by the Biotechnology and Biological Sciences Research Council, grant awards BB/ P019072/1 to J.M.C., M.F.A., P.A.S., C.U., and J.B. and BB/ T004363/1 to S.A.H., C.U. and J.B.; funding from HarvestPlus to N.I.M.N. and A.A.T.J.; a studentship from the John Innes Foundation to R.M. and a Wellcome Trust studentship to Y.M.L.M.
Publisher Copyright:
VC The Author(s) 2022.
PY - 2023/1/2
Y1 - 2023/1/2
N2 - Dietary deficiencies of iron and zinc cause human malnutrition that can be mitigated by biofortified staple crops. Conventional breeding approaches to increase grain mineral concentrations in wheat (Triticum aestivum L.) have had only limited success, and our understanding of the genetic and physiological barriers to altering this trait is incomplete. Here we demonstrate that a transgenic approach combining endosperm-specific expression of the wheat VACUOLAR IRON TRANSPORTER gene TaVIT2-D with constitutive expression of the rice (Oryza sativa) NICOTIANAMINE SYNTHASE gene OsNAS2 significantly increases the total concentration of zinc and relocates iron to white-flour fractions. In two distinct bread wheat cultivars, we show that the so called VIT-NAS construct led to a two-fold increase in zinc in wholemeal flour, to ~50mg g
–1. Total iron was not significantly increased, but redistribution within the grain resulted in a three-fold increase in iron in highly pure, roller-milled white flour, to ~25mg g
–1. Interestingly, expression of OsNAS2 partially restored iron translocation to the aleurone, which is iron depleted in grain overexpressing TaVIT2 alone. A greater than three-fold increase in the level of the natural plant metal chelator nicotianamine in the grain of VIT-NAS lines corresponded with improved iron and zinc bioaccessibility in white flour. The growth of VIT-NAS plants in the greenhouse was indistinguishable from untransformed controls. Our results provide insights into mineral translocation and distribution in wheat grain and demonstrate that the individual and combined effects of the two transgenes can enhance the nutritional quality of wheat beyond what is possible by conventional breeding.
AB - Dietary deficiencies of iron and zinc cause human malnutrition that can be mitigated by biofortified staple crops. Conventional breeding approaches to increase grain mineral concentrations in wheat (Triticum aestivum L.) have had only limited success, and our understanding of the genetic and physiological barriers to altering this trait is incomplete. Here we demonstrate that a transgenic approach combining endosperm-specific expression of the wheat VACUOLAR IRON TRANSPORTER gene TaVIT2-D with constitutive expression of the rice (Oryza sativa) NICOTIANAMINE SYNTHASE gene OsNAS2 significantly increases the total concentration of zinc and relocates iron to white-flour fractions. In two distinct bread wheat cultivars, we show that the so called VIT-NAS construct led to a two-fold increase in zinc in wholemeal flour, to ~50mg g
–1. Total iron was not significantly increased, but redistribution within the grain resulted in a three-fold increase in iron in highly pure, roller-milled white flour, to ~25mg g
–1. Interestingly, expression of OsNAS2 partially restored iron translocation to the aleurone, which is iron depleted in grain overexpressing TaVIT2 alone. A greater than three-fold increase in the level of the natural plant metal chelator nicotianamine in the grain of VIT-NAS lines corresponded with improved iron and zinc bioaccessibility in white flour. The growth of VIT-NAS plants in the greenhouse was indistinguishable from untransformed controls. Our results provide insights into mineral translocation and distribution in wheat grain and demonstrate that the individual and combined effects of the two transgenes can enhance the nutritional quality of wheat beyond what is possible by conventional breeding.
UR - http://www.scopus.com/inward/record.url?scp=85145424689&partnerID=8YFLogxK
U2 - 10.1093/plphys/kiac499
DO - 10.1093/plphys/kiac499
M3 - Article
C2 - 36308454
AN - SCOPUS:85145424689
SN - 1532-2548
VL - 191
SP - 528
EP - 541
JO - Plant physiology
JF - Plant physiology
IS - 1
ER -
