OsZIP7 functions in xylem loading in roots and inter-vascular transfer in nodes to deliver Zn/Cd to grain in rice

• Published in: Biochemical and biophysical research communications Vol. 512; no. 1; pp. 112 - 118
• Main Authors: Tan, Longtao, Zhu, Yuxing, Fan, Tony, Peng, Can, Wang, Jiurong, Sun, Liang, Chen, Caiyan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 23.04.2019
• Subjects: brown rice; Cadmium; Cadmium - metabolism; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Gene Expression Regulation, Plant; Gene Knockout Techniques; Genes, Plant; Hydroponics; Ion transporter; isotopes; leaves; Models, Biological; mutants; nutrition; Oryza - genetics; Oryza - growth & development; Oryza - metabolism; Oryza sativa; OsZIP7; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - metabolism; Plant Vascular Bundle - metabolism; Plants, Genetically Modified; plasma membrane; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Rice; roots; staple crops; vascular bundles; xylem; Xylem - metabolism; Zinc; Zinc - metabolism; Cadmium; Ion transporter; Zinc; OsZIP7; Rice
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2019.03.024

Rice has lower zinc (Zn) but higher cadmium (Cd) content in grains than other staple crops. Understanding the molecular mechanisms involved in Zn and Cd transportation could benefit homeostatic control, facilitating optimisation of Zn and Cd levels to provide maximum nutrition and safety. In this study, we functionally characterised in planta the rice (Oryza sativa) transporter OsZIP7, which encodes a plasma membrane-localised protein with influx transport activity for both Zn and Cd. OsZIP7 was expressed in parenchyma cells of vascular bundles in roots and nodes. OsZIP7 knockout resulted in retention of Zn and Cd in roots and basal nodes, which hindered their upward delivery to upper nodes and brown rice. And a short-term labelling experiment with the stable 67Zn isotope showed that Zn was distributed toward roots and basal regions and away from leaves in the mutant compared with wild-type rice. Thus, OsZIP7 plays an integral role in xylem loading in roots and inter-vascular transfer in nodes to preferentially deliver Zn and Cd to developing tissues and rice grains. •OsZIP7 expression is increased markedly in parenchyma cells of vascular bundles in roots and nodes under Zn deficiency and Cd stress.•OsZIP7 protein is localised to plasma membrane with influx transport activity for both Zn and Cd.•OsZIP7 knockout resulted in retention of Zn and Cd in roots and nodes.•OsZIP7 plays a key role in xylem-loading in roots and inter-vascular transfer in nodes to deliver Zinc and Cadmium upward in Rice (Oryza sativa L.)