title: Ethylene-dependent aerenchyma formation in adventitious roots is regulated differently in rice and maize.
abstract: In roots of gramineous plants, lysigenous aerenchyma is created by the death and lysis of cortical cells. Rice (Oryza sativa) constitutively forms aerenchyma under aerobic conditions, and its formation is further induced under oxygen-deficient conditions. However, maize (Zea mays) develops aerenchyma only under oxygen-deficient conditions. Ethylene is involved in lysigenous aerenchyma formation. Here, we investigated how ethylene-dependent aerenchyma formation is differently regulated between rice and maize. For this purpose, in rice, we used the reduced culm number1 (rcn1) mutant, in which ethylene biosynthesis is suppressed. Ethylene is converted from 1-aminocyclopropane-1-carboxylic acid (ACC) by the action of ACC oxidase (ACO). We found that OsACO5 was highly expressed in the wild type, but not in rcn1, under aerobic conditions, suggesting that OsACO5 contributes to aerenchyma formation in aerated rice roots. By contrast, the ACO genes in maize roots were weakly expressed under aerobic conditions, and thus ACC treatment did not effectively induce ethylene production or aerenchyma formation, unlike in rice. Aerenchyma formation in rice roots after the initiation of oxygen-deficient conditions was faster and greater than that in maize. These results suggest that the difference in aerenchyma formation in rice and maize is due to their different mechanisms for regulating ethylene biosynthesis.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan. atkyama@agr.nagoya-u.ac.jp.
authors.forename: Takaki
authors.initials: T
authors.lastname: Yamauchi
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mori
authors.affiliation: Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-8589, Japan.
authors.forename: Itsuro
authors.initials: I
authors.lastname: Takamure
authors.affiliation: Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido, 080-8555, Japan.
authors.forename: Kiyoaki
authors.initials: K
authors.lastname: Kato
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan. nakazono@agr.nagoya-u.ac.jp.
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakazono
mesh_terms: D003521:Cyclopropanes / Q000494:pharmacology; D005030:Ethylenes / Q000378:metabolism*; D012275:Oryza / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism / Q000502:physiology*; D018517:Plant Roots / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology; D013045:Species Specificity; D003313:Zea mays / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*
chemical_list: D003521:Cyclopropanes; D005030:Ethylenes; D010937:Plant Growth Regulators; C036216:ethylene; C412563:1-methylcyclopropene; D010100:Oxygen
keywords: 1-aminocyclopropane-1-carboxylic acid (ACC); constitutive aerenchyma formation; ethylene; inducible aerenchyma formation; maize (Zea mays); rice (Oryza sativa)