title: LEUNIG_HOMOLOG and LEUNIG regulate seed mucilage extrusion in Arabidopsis.
abstract: LEUNIG (LUG) and LEUNIG_HOMOLOG (LUH) encode two closely related Arabidopsis proteins, belonging to the Gro/TLE family of transcriptional co-repressors. These two genes were previously shown to exhibit partially overlapping functions in embryo and flower development. In this report, the role of both LUH and LUG on seed mucilage extrusion was examined. Seed mucilage extrusion occurs after the seeds are imbibed, serving as functional aid in seed hydration, germination, and dispersal. While luh-1 mutants exhibited strong defects in seed mucilage extrusion, lug-3 mutants exhibited a minor phenotype in mucilage extrusion. Further characterization indicates that luh-1 does not exhibit any obvious defect in seed epidermal cell differentiation, mucilage synthesis, or mucilage deposition, suggesting a specific role of LUH in mucilage extrusion. This seed mucilage phenotype of luh-1 is identical to that of mucilage modified 2 (mum2) mutants. MUM2 encodes a β-galactosidase required for the modification of the mucilage. Quantitative reverse transcription polymerase chain reaction of RNA extracted from siliques detected a slight decrease of MUM2 mRNA in the luh-1 mutant compared to the wild type. Together, LUH and possibly LUG may specifically regulate mucilage extrusion by promoting the expression of genes required for mucilage maturation.
authors.affiliation: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Minh
authors.initials: M
authors.lastname: Bui
authors.forename: Nathan
authors.initials: N
authors.lastname: Lim
authors.forename: Paja
authors.initials: P
authors.lastname: Sijacic
authors.forename: Zhongchi
authors.initials: Z
authors.lastname: Liu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002473:Cell Wall / Q000201:enzymology; D005697:Galactosides / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D053147:Plant Exudates / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000502:physiology* / Q000648:ultrastructure; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005697:Galactosides; C417768:LUG protein, Arabidopsis; C560407:LUH protein, Arabidopsis; D053147:Plant Exudates; D012097:Repressor Proteins; C445880:SEUSS protein, Arabidopsis; D014157:Transcription Factors; C007816:beta-galactoside