title: Rice OsYSL15 is an iron-regulated iron(III)-deoxymugineic acid transporter expressed in the roots and is essential for iron uptake in early growth of the seedlings.
abstract: Graminaceous plants take up iron through YS1 (yellow stripe 1) and YS1-like (YSL) transporters using iron-chelating compounds known as mugineic acid family phytosiderophores. We examined the expression of 18 rice (Oryza sativa L.) YSL genes (OsYSL1-18) in the epidermis/exodermis, cortex, and stele of rice roots. Expression of OsYSL15 in root epidermis and stele was induced by iron deficiency and showed daily fluctuation. OsYSL15 restored a yeast mutant defective in iron uptake when supplied with iron(III)-deoxymugineic acid and transported iron(III)-deoxymugineic acid in Xenopus laevis oocytes. An OsYSL15-green fluorescent protein fusion was localized to the plasma membrane when transiently expressed in onion epidermal cells. OsYSL15 promoter-beta-glucuronidase analysis revealed that OsYSL15 expression in roots was dominant in the epidermis/exodermis and phloem cells under conditions of iron deficiency and was detected only in phloem under iron sufficiency. These results strongly suggest that OsYSL15 is the dominant iron(III)-deoxymugineic acid transporter responsible for iron uptake from the rhizosphere and is also responsible for phloem transport of iron. OsYSL15 was also expressed in flowers, developing seeds, and in the embryonic scutellar epithelial cells during seed germination. OsYSL15 knockdown seedlings showed severe arrest in germination and early growth and were rescued by high iron supply. These results demonstrate that rice OsYSL15 plays a crucial role in iron homeostasis during the early stages of growth.
authors.affiliation: Graduate School of Agricultural and Life Sciences, the University of Tokyo, 1-1-1 Yayoi, Tokyo 113-8657, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Inoue
authors.forename: Takanori
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nozoye
authors.forename: Michiko
authors.initials: M
authors.lastname: Takahashi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kakei
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Suzuki
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakazono
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: D000818:Animals; D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001483:Base Sequence; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D005260:Female; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D007501:Iron / Q000378:metabolism*; D000090463:Iron Deficiencies; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000166:cytology; D009928:Organ Specificity / Q000502:physiology; D027361:Organic Anion Transporters / Q000096:biosynthesis* / Q000235:genetics; D012275:Oryza / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D027361:Organic Anion Transporters; D010940:Plant Proteins; D001383:Azetidinecarboxylic Acid; C052864:2'-deoxymugineic acid; D007501:Iron