Expression of HvYS1 in Rice Increases Iron Uptake and Seed Loading via Selective Iron Transport

Several metal transporters in plants accommodate multiple cations, including some which are toxic to humans. Attempts at increasing iron and zinc content of rice endosperm by overexpressing metal transporters unintentionally led to accumulation of copper, manganese, and cadmium. Unlike other metal transporters, the barley Yellow Stripe 1 (HvYS1) is specific for iron.

The team of Raviraj Banakar of the Universitat de Lleida-Agrotecnio Center Lleida investigated the basis of this preference by expressing HvYS1 in rice under the control of the maize ubiquitin1 promoter. Plants expressing HvYS1 had slight increases in iron uptake, translocation, seed accumulation, and endosperm loading, but had no changes in the uptake of zinc, manganese or copper. The zinc and manganese levels in the endosperm did not differ between the wild-type and HvYS1 lines, but the latter had significantly lower copper levels. The transgenic lines also showed a significantly reduced cadmium uptake, translocation, and accumulation in the rice seeds.

These results suggest that HvYS1 promotes the preferential mobilization and loading of iron. The increased loading of iron displaces copper and cadmium in the rice seeds.

For more information, read the full article in Plant Biotechnology Journal.