title: Identification of marneral synthase, which is critical for growth and development in Arabidopsis.
abstract: Plants produce structurally diverse triterpenoids, which are important for their life and survival. Most triterpenoids and sterols share a common biosynthetic intermediate, 2,3-oxidosqualene (OS), which is cyclized by 2,3-oxidosqualene cyclase (OSC). To investigate the role of an OSC, marneral synthase 1 (MRN1), in planta, we characterized a Arabidopsis mrn1 knock-out mutant displaying round-shaped leaves, late flowering, and delayed embryogenesis. Reduced growth of mrn1 was caused by inhibition of cell expansion and elongation. Marnerol, a reduced form of marneral, was detected in Arabidopsis overexpressing MRN1, but not in the wild type or mrn1. Alterations in the levels of sterols and triterpenols and defects in membrane integrity and permeability were observed in the mrn1. In addition, GUS expression, under the control of the MRN1 gene promoter, was specifically detected in shoot and root apical meristems, which are responsible for primary growth, and the mRNA expression of Arabidopsis clade II OSCs was preferentially observed in roots and siliques containing developing seeds. The eGFP:MRN1 was localized to the endoplasmic reticulum in tobacco protoplasts. Taken together, this report provides evidence that the unusual triterpenoid pathway via marneral synthase is important for the growth and development of Arabidopsis.
authors.affiliation: Department of Plant Biotechnology, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Young S
authors.initials: YS
authors.lastname: Go
authors.forename: Saet B
authors.initials: SB
authors.lastname: Lee
authors.forename: Hae J
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jungmook
authors.initials: J
authors.lastname: Kim
authors.forename: Hyo-Young
authors.initials: HY
authors.lastname: Park
authors.forename: Jeong-Kook
authors.initials: JK
authors.lastname: Kim
authors.forename: Kyomi
authors.initials: K
authors.lastname: Shibata
authors.forename: Takao
authors.initials: T
authors.lastname: Yokota
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ohyama
authors.forename: Toshiya
authors.initials: T
authors.lastname: Muranaka
authors.forename: Siméon
authors.initials: S
authors.lastname: Arseniyadis
authors.forename: Mi C
authors.initials: MC
authors.lastname: Suh
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D005808:Genes, Recessive; D018525:Germination / Q000235:genetics; D019751:Intramolecular Transferases / Q000235:genetics* / Q000378:metabolism*; D018519:Meristem / Q000235:genetics; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000166:cytology / Q000235:genetics; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D018520:Plant Shoots / Q000235:genetics; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D014026:Nicotiana / Q000235:genetics; D014315:Triterpenes / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D011994:Recombinant Proteins; D014315:Triterpenes; C531276:marneral; D019751:Intramolecular Transferases; C568454:marneral synthase, Arabidopsis