title: DIMINUTO 1 affects the lignin profile and secondary cell wall formation in Arabidopsis.
abstract: Brassinosteroids (BRs) play a crucial role in plant growth and development and DIMINUTO 1 (DIM1), a protein involved in BR biosynthesis, was previously identified as a cell elongation factor in Arabidopsis thaliana. Through promoter expression analysis, we showed that DIM1 was expressed in most of the tissue types in seedlings and sectioning of the inflorescence stem revealed that DIM1 predominantly localizes to the xylem vessels and in the interfascicular cambium. To investigate the role of DIM1 in cell wall formation, we generated loss-of-function and gain-of-function mutants. Disruption of the gene function caused a dwarf phenotype with up to 38 and 23% reductions in total lignin and cellulose, respectively. Metabolite analysis revealed a significant reduction in the levels of fructose, glucose and sucrose in the loss-of-function mutant compared to the wild type control. The loss-of-function mutant also had a lower S/G lignin monomer ratio relative to wild type, but no changes were detected in the gain-of-function mutant. Phloroglucinol and toluidine blue staining showed a size reduction of the vascular apparatus with smaller and disintegrated xylem vessels in the inflorescence stem of the loss-of-function mutant. Taken together, these data indicate a role for DIM1 in secondary cell wall formation. Moreover, this study demonstrated the potential role of BR hormones in modulating cell wall structure and composition.
authors.affiliation: Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada.
authors.forename: Zakir
authors.initials: Z
authors.lastname: Hossain
authors.forename: Brian
authors.initials: B
authors.lastname: McGarvey
authors.forename: Lisa
authors.initials: L
authors.lastname: Amyot
authors.forename: Margaret
authors.initials: M
authors.lastname: Gruber
authors.forename: Jinwook
authors.initials: J
authors.lastname: Jung
authors.forename: Abdelali
authors.initials: A
authors.lastname: Hannoufa
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008031:Lignin / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C091574:DIM1 protein, Arabidopsis; D008031:Lignin