Enhanced iron flow into the endosperm by OsYSL2 increases the iron content of rice grain.

Abstract

Fortifying food crops with iron (Fe) can combat Fe deficiency, a leading global human nutritional disorder. To generate transgenic rice seeds containing high levels of Fe, an appropriate Fe transporter must be selected and tightly regulated. Nicotianamine, an Fe chelator, is indispensable for Fe translocation within plants. The Fe concentration in rice seeds, especially in the endosperm, was decreased as a result of the knock down or constitutive overexpression of the Fe-nicotianamine transporter OsYSL2, suggesting that tightly regulated OsYSL2 expression is essential for Fe transport to the endosperm. Thus, OsYSL2 expression was driven by the sucrose transporter OsSUT1 promoter. Consequently, we succeeded in producing transgenic rice seeds with a 4.4-fold higher level of Fe in the endosperm.