title: Gibberellin biosynthesis and signal transduction is essential for internode elongation in deepwater rice.
abstract: Under flooded conditions, the leaves and internodes of deepwater rice can elongate above the water surface to capture oxygen and prevent drowning. Our previous studies showed that three major quantitative trait loci (QTL) regulate deepwater-dependent internode elongation in deepwater rice. In this study, we investigated the age-dependent internode elongation in deepwater rice. We also investigated the relationship between deepwater-dependent internode elongation and the phytohormone gibberellin (GA) by physiological and genetic approach using a QTL pyramiding line (NIL-1 + 3 + 12). Deepwater rice did not show internode elongation before the sixth leaf stage under deepwater condition. Additionally, deepwater-dependent internode elongation occurred on the sixth and seventh internodes during the sixth leaf stage. These results indicate that deepwater rice could not start internode elongation until the sixth leaf stage. Ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) method for the phytohormone contents showed a deepwater-dependent GA1 and GA4 accumulation in deepwater rice. Additionally, a GA inhibitor abolished deepwater-dependent internode elongation in deepwater rice. On the contrary, GA feeding mimicked internode elongation under ordinary growth conditions. However, mutations in GA biosynthesis and signal transduction genes blocked deepwater-dependent internode elongation. These data suggested that GA biosynthesis and signal transduction are essential for deepwater-dependent internode elongation in deepwater rice.
authors.affiliation: Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi, 464-8601.
authors.forename: Madoka
authors.initials: M
authors.lastname: Ayano
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kani
authors.forename: Mikiko
authors.initials: M
authors.lastname: Kojima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibara
authors.forename: Takuya
authors.initials: T
authors.lastname: Kitaoka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kuroha
authors.forename: Rosalyn B
authors.initials: RB
authors.lastname: Angeles-Shim
authors.forename: Hidemi
authors.initials: H
authors.lastname: Kitano
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nagai
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Ashikari
mesh_terms: D002851:Chromatography, High Pressure Liquid; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000032:analysis / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000032:analysis / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D040641:Quantitative Trait Loci / Q000235:genetics; D015398:Signal Transduction; D053719:Tandem Mass Spectrometry; D014230:Triazoles / Q000494:pharmacology; D014867:Water / Q000502:physiology
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014230:Triazoles; D014867:Water; C092705:uniconazole; D010100:Oxygen
keywords: gibberellin