title: RCN1/OsABCG5, an ATP-binding cassette (ABC) transporter, is required for hypodermal suberization of roots in rice (Oryza sativa).
abstract: Suberin is a complex polymer composed of aliphatic and phenolic compounds. It is a constituent of apoplastic plant interfaces. In many plant species, including rice (Oryza sativa), the hypodermis in the outer part of roots forms a suberized cell wall (the Casparian strip and/or suberin lamellae), which inhibits the flow of water and ions and protects against pathogens. To date, there is no genetic evidence that suberin forms an apoplastic transport barrier in the hypodermis. We discovered that a rice reduced culm number1 (rcn1) mutant could not develop roots longer than 100 mm in waterlogged soil. The mutated gene encoded an ATP-binding cassette (ABC) transporter named RCN1/OsABCG5. RCN1/OsABCG5 gene expression in the wild type was increased in most hypodermal and some endodermal roots cells under stagnant deoxygenated conditions. A GFP-RCN1/OsABCG5 fusion protein localized at the plasma membrane of the wild type. Under stagnant deoxygenated conditions, well suberized hypodermis developed in wild types but not in rcn1 mutants. Under stagnant deoxygenated conditions, apoplastic tracers (periodic acid and berberine) were blocked at the hypodermis in the wild type but not in rcn1, indicating that the apoplastic barrier in the mutant was impaired. The amount of the major aliphatic suberin monomers originating from C(28) and C(30) fatty acids or ω-OH fatty acids was much lower in rcn1 than in the wild type. These findings suggest that RCN1/OsABCG5 has a role in the suberization of the hypodermis of rice roots, which contributes to formation of the apoplastic barrier.
authors.affiliation: Department of Bioscience, Fukui Prefectural University, 4-1-1 Matsuoka-Kenjyojima, Eiheiji, Fukui, 910-1195, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Shiono
authors.forename: Miho
authors.initials: M
authors.lastname: Ando
authors.forename: Shunsaku
authors.initials: S
authors.lastname: Nishiuchi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Takahashi
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Watanabe
authors.forename: Motoaki
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Naoko
authors.initials: N
authors.lastname: Yasuno
authors.forename: Utako
authors.initials: U
authors.lastname: Yamanouchi
authors.forename: Masaru
authors.initials: M
authors.lastname: Fujimoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Takanashi
authors.forename: Kosala
authors.initials: K
authors.lastname: Ranathunge
authors.forename: Rochus B
authors.initials: RB
authors.lastname: Franke
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Shitan
authors.forename: Naoko K
authors.initials: NK
authors.lastname: Nishizawa
authors.forename: Itsuro
authors.initials: I
authors.lastname: Takamure
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yano
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Tsutsumi
authors.forename: Lukas
authors.initials: L
authors.lastname: Schreiber
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Yazaki
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakazono
authors.forename: Kiyoaki
authors.initials: K
authors.lastname: Kato
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D008031:Lignin / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D009154:Mutation; D012275:Oryza / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins; D014867:Water / Q000502:physiology*
chemical_list: D018528:ATP-Binding Cassette Transporters; D008055:Lipids; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014867:Water; C065875:suberin; D008031:Lignin
keywords: Casparian strip; Oryza sativa; WBC/WHITE-subgroup; apoplastic barrier; exodermis; lignin; reduced culm number1 (rcn1); suberin; suberin lamellae; waterlogging