title: The tillering phenotype of the rice plastid terminal oxidase (PTOX) loss-of-function mutant is associated with strigolactone deficiency.
abstract: The significance of plastid terminal oxidase (PTOX) in phytoene desaturation and chloroplast function has been demonstrated using PTOX-deficient mutants, particularly in Arabidopsis. However, studies on its role in monocots are lacking. Here, we report cloning and characterization of the rice (Oryza sativa) PTOX1 gene. Using Ecotype Targeting Induced Local Lesions IN Genomes (EcoTILLING) and TILLING as forward genetic tools, we identified the causative mutation of an EMS mutant characterized by excessive tillering, semi-dwarfism and leaf variegation that corresponded to the PTOX1 gene. The tillering and semi-dwarf phenotypes of the ptox1 mutant are similar to phenotypes of known strigolactone (SL)-related rice mutants, and both phenotypic traits could be rescued by application of the synthetic SL GR24. The ptox1 mutant accumulated phytoene in white leaf sectors with a corresponding deficiency in β-carotene, consistent with the expected function of PTOX1 in promoting phytoene desaturase activity. There was also no accumulation of the carotenoid-derived SL ent-2'-epi-5-deoxystrigol in root exudates. Elevated concentrations of auxin were detected in the mutant, supporting previous observations that SL interaction with auxin is important in shoot branching control. Our results demonstrate that PTOX1 is required for both carotenoid and SL synthesis resulting in SL-deficient phenotypes in rice.
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Muluneh
authors.initials: M
authors.lastname: Tamiru
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.|Iwate Agricultural Research Center, Narita 20-1, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Abe
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Hiroe
authors.initials: H
authors.lastname: Utsushi
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Kakoto
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.|United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, 020-8550, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takagi
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Fujisaki
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.|United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, 020-8550, Japan.
authors.forename: Jerwin R
authors.initials: JR
authors.lastname: Undan
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Sujay
authors.initials: S
authors.lastname: Rakshit
authors.affiliation: Department of Biology, Nippon Medical School, Kawasaki, Kanagawa, 211-0063, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Takaichi
authors.affiliation: Department of Biosciences, Faculty of Science and Technology, Teikyo University, Utsunomiya, Tochigi, 320-8851, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.affiliation: Department of Biosciences, Faculty of Science and Technology, Teikyo University, Utsunomiya, Tochigi, 320-8851, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Yokota
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.|Centre for Biological Sciences, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Terry
authors.affiliation: Iwate Biotechnology Research Center, Narita 22-174-4, Kitakami, Iwate, 024-0003, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Terauchi
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics; D002338:Carotenoids / Q000378:metabolism; D003001:Cloning, Molecular; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D005819:Genetic Markers; D006575:Heterocyclic Compounds, 3-Ring / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism; D007783:Lactones / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010088:Oxidoreductases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000201:enzymology* / Q000235:genetics; D011110:Polymorphism, Genetic; D020539:Sequence Analysis, Protein
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D002338:Carotenoids; D005819:Genetic Markers; D006575:Heterocyclic Compounds, 3-Ring; D007210:Indoleacetic Acids; D007783:Lactones; D010088:Oxidoreductases; D010940:Plant Proteins; C000591191:GR24 strigolactone; C405742:IM protein, Arabidopsis; C100185:(all-E) phytoene
keywords: EcoTILLING; Oryza sativa (rice); PTOX; carotenoid synthesis; mesocotyl elongation; strigolactone; tillering