title: Expression of iron-acquisition-related genes in iron-deficient rice is co-ordinately induced by partially conserved iron-deficiency-responsive elements.
abstract: Rice plants (Oryza sativa L.) utilize the iron chelators known as mugineic acid family phytosiderophores (MAs) to acquire iron from the rhizosphere. Synthesis of MAs and uptake of MA-chelated iron are strongly induced under conditions of iron deficiency. Microarray analysis was used to characterize the expression profile of rice in response to iron deficiency at the genomic level. mRNA extracted from iron-deficient or iron-sufficient rice roots or leaves was hybridized to a rice array containing 8987 cDNA clones. An induction ratio of greater than 2.0 in roots was observed for 57 genes, many of which are involved in iron-uptake mechanisms, including every identified or predicted step in the methionine cycle and the biosynthesis of MAs from methionine. Northern analysis confirmed that the expression of genes encoding every step in the methionine cycle is thoroughly induced by iron deficiency in roots, and almost thoroughly induced in leaves. A promoter search revealed that the iron-deficiency-induced genes related to iron uptake possessed sequences homologous to the iron-deficiency-responsive cis-acting elements IDE1 and IDE2 in their promoter regions, at a higher rate than that showing no induction under Fe deficiency. These results suggest that rice genes involved in iron acquisition are co-ordinately regulated by conserved mechanisms in response to iron deficiency, in which IDE-mediated regulation plays a significant role.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Motofumi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Inoue
authors.forename: Reiko Nakanishi
authors.initials: RN
authors.lastname: Itai
authors.forename: Michiko
authors.initials: M
authors.lastname: Takahashi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mori
authors.forename: Naoko K
authors.initials: NK
authors.lastname: Nishizawa
mesh_terms: D015152:Blotting, Northern; D017124:Conserved Sequence; D004798:Enzymes / Q000235:genetics; D020224:Expressed Sequence Tags; D017343:Genes, Plant; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000378:metabolism; D000090463:Iron Deficiencies; D008715:Methionine / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D012436:S-Adenosylmethionine / Q000378:metabolism
chemical_list: D004798:Enzymes; D007502:Iron Chelating Agents; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D012436:S-Adenosylmethionine; D008715:Methionine; D007501:Iron