title: Overexpression of OsHMA3 enhances Cd tolerance and expression of Zn transporter genes in rice.
abstract: As a member of the heavy metal ATPase (HMA) family, OsHMA3 is a tonoplast-localized transporter for Cd in the roots of rice (Oryza sativa). Overexpression of OsHMA3 selectively reduces Cd accumulation in the grain. Further characterization in the present study revealed that overexpression of OsHMA3 also enhances the tolerance to toxic Cd. The growth of both the roots and shoots was similar in the absence of Cd between an OsHMA3-overexpressed line and vector control, but the Cd-inhibited growth was significantly alleviated in the OsHMA3-overexpressed line. The overexpressed line showed higher Cd concentration in the roots, but lower Cd concentration in the shoots compared with the wild-type rice and vector control line, indicating that overexpression of OsHMA3 enhanced vacuolar sequestration of Cd in the roots. The Zn concentration in the roots of the OsHMA3-overexpressed line was constantly higher than that of vector control, but the Zn concentration in the shoots was similar between the overexpressed line and vector control. Five transporter genes belonging to the ZIP family were constitutively up-regulated in the OsHMA3-overexpressed line. These results suggest that shoot Zn level was maintained by up-regulating these genes involved in the Zn uptake/translocation. Taken together, overexpression of OsHMA3 is an efficient way to reduce Cd accumulation in the grain and to enhance Cd tolerance in rice.
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, Japan.
authors.forename: Akimasa
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamaji
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, Japan maj@rib.okayama-u.ac.jp.
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Ma
mesh_terms: D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015854:Up-Regulation; D014617:Vacuoles / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D027682:Cation Transport Proteins; D010940:Plant Proteins; D002104:Cadmium; D015032:Zinc
keywords: Cd; Oryza sativa; OsHMA3; Zn transporter; overexpression; tolerance.