Open AccessThe expression of heterologous Fe ( III ) phytosiderophore transporter Hv YS 1 in rice increases Fe uptake, translocation and seed loading and excludes heavy metals by selective Fe transport
Author(s) -
Banakar Raviraj,
Alvarez Fernández Ána,
Abadía Javier,
Capell Teresa,
Christou Paul
Publication year - 2017
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.12637
Subject(s) - endosperm , chromosomal translocation , shoot , cadmium , biology , metal , transporter , divalent , zinc , biophysics , microbiology and biotechnology , biochemistry , botany , chemistry , gene , organic chemistry
Summary Many metal transporters in plants are promiscuous, accommodating multiple divalent cations including some which are toxic to humans. Previous attempts to increase the iron (Fe) and zinc (Zn) content of rice endosperm by overexpressing different metal transporters have therefore led unintentionally to the accumulation of copper (Cu), manganese (Mn) and cadmium (Cd). Unlike other metal transporters, barley Yellow Stripe 1 (Hv YS 1) is specific for Fe. We investigated the mechanistic basis of this preference by constitutively expressing Hv YS 1 in rice under the control of the maize ubiquitin1 promoter and comparing the mobilization and loading of different metals. Plants expressing Hv YS 1 showed modest increases in Fe uptake, root‐to‐shoot translocation, seed accumulation and endosperm loading, but without any change in the uptake and root‐to‐shoot translocation of Zn, Mn or Cu, confirming the selective transport of Fe. The concentrations of Zn and Mn in the endosperm did not differ significantly between the wild‐type and Hv YS 1 lines, but the transgenic endosperm contained significantly lower concentrations of Cu. Furthermore, the transgenic lines showed a significantly reduced Cd uptake, root‐to‐shoot translocation and accumulation in the seeds. The underlying mechanism of metal uptake and translocation reflects the down‐regulation of promiscuous endogenous metal transporters revealing an internal feedback mechanism that limits seed loading with Fe. This promotes the preferential mobilization and loading of Fe, therefore displacing Cu and Cd in the seed.