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Zea mays Fe deficiency‐related 4 (Zm FDR 4) functions as an iron transporter in the plastids of monocots
Author(s) -
Zhang XiuYue,
Zhang Xi,
Zhang Qi,
Pan XiaoXi,
Yan LuoChen,
Ma XiaoJuan,
Zhao WeiZhong,
Qi XiaoTing,
Yin LiPing
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13482
Subject(s) - plastid , zea mays , transporter , dmt1 , iron deficiency , chemistry , biology , genetics , chloroplast , medicine , gene , agronomy , anemia
Summary Iron (Fe)‐homeostasis in the plastids is closely associated with Fe transport proteins that prevent Fe from occurring in its toxic free ionic forms. However, the number of known protein families related to Fe transport in the plastids (about five) and the function of iron in non‐green plastids is limited. In the present study, we report the functional characterization of Zea mays Fe deficiency‐related 4 ( Zm FDR 4 ), which was isolated from a differentially expressed clone of a cDNA library of Fe deficiency‐induced maize roots. Zm FDR 4 is homologous to the bacterial FliP superfamily, coexisted in both algae and terrestrial plants, and capable of restoring the normal growth of the yeast mutant fet3fet4 , which possesses defective Fe uptake systems. Zm FDR 4 mRNA is ubiquitous in maize and is inducible by iron deficiency in wheat. Transient expression of the 35S:Zm FDR 4– eGFP fusion protein in rice protoplasts indicated that Zm FDR 4 maybe localizes to the plastids envelope and thylakoid. In 35S:c‐Myc‐Zm FDR 4 transgenic tobacco, immunohistochemistry and immunoblotting confirmed that Zm FDR 4 is targeted to both the chloroplast envelope and thylakoid. Meanwhile, ultrastructure analysis indicates that Zm FDR 4 promotes the density of plastids and accumulation of starch grains. Moreover, Bathophenanthroline disulfonate ( BPDS ) colorimetry and inductively coupled plasma mass spectrometry ( ICP ‐ MS ) indicate that Zm FDR 4 is related to Fe uptake by plastids and increases seed Fe content. Finally, 35S:c‐Myc‐Zm FDR 4 transgenic tobacco show enhanced photosynthetic efficiency. Therefore, the results of the present study demonstrate that Zm FDR 4 functions as an iron transporter in monocot plastids and provide insight into the process of Fe uptake by plastids.