A highly potential Zn biofortification tool: MTP1 in Triticum aestivum

TaMTPs belong to metal tolerance proteins (MTPs) family in common wheat and have significant potential to address the "hidden hunger" caused by inadequate dietary intake of a key micronutrient (Zn). In this study, a total of 33 MTP members in Triticum aestivum were identified, among which six TaMTP1-likes were closely related to Arabidopsis thaliana MTP1 and were designated as TaMTP1-A/B/D and TaMTP1.1-A/B/D. When heterologously expressed in yeast mutants, TaMTP1-likes complemented their hypersensitivity to Zn and Co, and three of the most metal-resistant members, TaMTP1-A, TaMTP1-D and TaMTP1.1-B, were selected for further subcellular localization and functional experiment in Arabidopsis and rice. The results showed that all three proteins were localized in the vacuole membrane, that TaMTP1-D was more resistant to Zn and less resistant to Co than other TaMTP1-like members, and that TaMTP1-D was expressed at a higher level in the endosperm than other members. All results reveal that the use of TaMTP1-D for biofortification can substantially increase the content of Zn in the edible part of wheat and avoid the overaccumulation of Co, suggesting that TaMTP1-D is a potential Zn biofortifier / bioreinforcement.