title: Iron uptake system mediates nitrate-facilitated cadmium accumulation in tomato (Solanum lycopersicum) plants.
abstract: Nitrogen (N) management is a promising agronomic strategy to minimize cadmium (Cd) contamination in crops. However, it is unclear how N affects Cd uptake by plants. Wild-type and iron uptake-inefficient tomato (Solanum lycopersicum) mutant (T3238fer) plants were grown in pH-buffered hydroponic culture to investigate the direct effect of N-form on Cd uptake. Wild-type plants fed NO₃⁻ accumulated more Cd than plants fed NH₄⁺. Iron uptake and LeIRT1 expression in roots were also greater in plants fed NO₃⁻. However, in mutant T3238fer which loses FER function, LeIRT1 expression in roots was almost completely terminated, and the difference between NO₃⁻ and NH₄⁺ treatments vanished. As a result, the N-form had no effect on Cd uptake in this mutant. Furthermore, suppression of LeIRT1 expression by NO synthesis inhibition with either tungstate or L-NAME, also substantially inhibited Cd uptake in roots, and the difference between N-form treatments was diminished. Considering all of these findings, it was concluded that the up-regulation of the Fe uptake system was responsible for NO₃⁻-facilitated Cd accumulation in plants.
authors.affiliation: Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Bing Fang
authors.initials: BF
authors.lastname: Luo
authors.forename: Shao Ting
authors.initials: ST
authors.lastname: Du
authors.forename: Kai Xing
authors.initials: KX
authors.lastname: Lu
authors.forename: Wen Jing
authors.initials: WJ
authors.lastname: Liu
authors.forename: Xian Yong
authors.initials: XY
authors.lastname: Lin
authors.forename: Chong Wei
authors.initials: CW
authors.lastname: Jin
mesh_terms: D018533:Biomass; D002104:Cadmium / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D007501:Iron / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009566:Nitrates / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis; D009584:Nitrogen / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism
chemical_list: D009566:Nitrates; D010940:Plant Proteins; D002104:Cadmium; D009569:Nitric Oxide; D007501:Iron; D009584:Nitrogen