title: A role of OsGA20ox1 , encoding an isoform of gibberellin 20-oxidase, for regulation of plant stature in rice.
abstract: Gibberellin (GA) 20-oxidase (GA20ox) is a key enzyme that normally catalyzes the penultimate steps in GA biosynthesis. One of the GA20ox genes in rice (Oryza sativa L.), OsGA20ox2 ( SD1 ), is well known as the "Green Revolution gene", and loss-of function mutation in this locus causes semi-dwarfism. Another GA20ox gene, OsGA20ox1, has also been identified, but its contribution to plant stature has remained unclear because no suitable mutants have been available. We isolated a mutant, B142, tagged with a T-DNA containing three CaMV 35S promoters, which showed a tall, GA-overproduction phenotype. The final stature of the B142 mutant reflects internode overgrowth and is approximately twice that of its wild-type parent. This mutant responds to application of both GA3 and a GA biosynthesis inhibitor, indicating that it is a novel tall mutant of rice distinct from GA signaling mutants such as slr1 . The integrated T-DNAs, which contain three CaMV 35S promoters, are located upstream of the OsGA20ox1 open reading frame (ORF) in the B142 mutant genome. Analysis of mRNA and the endogenous GAs reveal that biologically active GA level is increased by up-regulation of the OsGA20ox1 gene in B142. Introduction of OsGA20ox1 cDNA driven by 35S promoter into the wild type phenocopies the morphological characteristics of B142. These results indicate that the elongated phenotype of the B142 mutant is caused by up-regulation of the OsGA20ox1 gene. Moreover, the final stature of rice was reduced by specific suppression of the OsGA20ox1 gene expression. This result indicates that not only OsGA20ox2 but also OsGA20ox1 affects plant stature.
authors.affiliation: Laboratory of Bio-control, Graduate School of Natural Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata 950-2181, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Oikawa
authors.forename: Masaji
authors.initials: M
authors.lastname: Koshioka
authors.forename: Kiyohide
authors.initials: K
authors.lastname: Kojima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yoshida
authors.forename: Motoshige
authors.initials: M
authors.lastname: Kawata
mesh_terms: D001665:Binding Sites / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D005875:Gibberellins / Q000096:biosynthesis / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D016254:Mutagenesis, Insertional; D009154:Mutation; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D010957:Plasmids / Q000235:genetics; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D014230:Triazoles / Q000494:pharmacology
chemical_list: D004269:DNA, Bacterial; D005875:Gibberellins; D007527:Isoenzymes; D016372:RNA, Antisense; D018749:RNA, Plant; D034741:RNA, Small Interfering; C036483:T-DNA; D014230:Triazoles; C007842:gibberellic acid; D006899:Mixed Function Oxygenases; C089210:gibberellin, 2-oxoglutarate-oxygen oxidoreductase (20-hydroxylating, oxidizing); C092705:uniconazole