title: Silicon decreases both uptake and root-to-shoot translocation of manganese in rice.
abstract: Silicon (Si) is known to alleviate manganese (Mn) toxicity in a number of plant species; however, the mechanisms responsible for this effect are poorly understood. Here, we investigated the interaction between Si and Mn in rice (Oryza sativa) by using a mutant defective in Si uptake. Silicon alleviated Mn toxicity in the wild-type (WT) rice, but not in the mutant exposed to high Mn. The Mn concentration in the shoots was decreased, but that in the roots was increased by Si in the WT. In contrast, the Mn concentration in the roots and shoots was unaffected by Si in the mutant. Furthermore, Si supply resulted in an increased Mn in the root cell sap, decreased Mn in the xylem sap in the WT, but these effects of Si were not observed in the mutant. A short-term labelling experiment with (54)Mn showed that the uptake of Mn was similar between plants with and without Si and between WT and the mutant. However, Si decreased root-to-shoot translocation of Mn in the WT, but not in the mutant. The expression of a Mn transporter gene for uptake, OsNramp5, was unaffected by a short exposure (<1 d) to Si, but down-regulated by relatively long-term exposure to Si in WT. In contrast, the expression of OsNramp5 was unaffected by Si in the mutant. These results indicated that Si-decreased Mn accumulation results from both Si-decreased root-to-shoot translocation of Mn, probably by the formation of Mn-Si complex in root cells, and uptake by down-regulating Mn transporter gene.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China University of Chinese Academy of Sciences, Beijing 100049, China Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Jing
authors.initials: J
authors.lastname: Che
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamaji
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Ji Feng
authors.initials: JF
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan maj@rib.okayama-u.ac.jp rfshen@issas.ac.cn.
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China maj@rib.okayama-u.ac.jp rfshen@issas.ac.cn.
authors.forename: Ren Fang
authors.initials: RF
authors.lastname: Shen
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008345:Manganese / Q000378:metabolism* / Q000633:toxicity; D026901:Membrane Transport Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism*; D011868:Radioisotopes; D012825:Silicon / Q000494:pharmacology*; D052584:Xylem / Q000187:drug effects / Q000378:metabolism
chemical_list: D026901:Membrane Transport Proteins; D010940:Plant Proteins; D011868:Radioisotopes; D008345:Manganese; D012825:Silicon
keywords: 54Mn; Mn toxicity; Mn transporter; Mn-Si complex; root-to-shoot translocation; silicon.