title: BRANCHLESS TRICHOMES links cell shape and cell cycle control in Arabidopsis trichomes.
abstract: Endoreplication, also called endoreduplication, is a modified cell cycle in which DNA is repeatedly replicated without subsequent cell division. Endoreplication is often associated with increased cell size and specialized cell shapes, but the mechanism coordinating DNA content with shape and size remains obscure. Here we identify the product of the BRANCHLESS TRICHOMES (BLT) gene, a protein of hitherto unknown function that has been conserved throughout angiosperm evolution, as a link in coordinating cell shape and nuclear DNA content in endoreplicated Arabidopsis trichomes. Loss-of-function mutations in BLT were found to enhance the multicellular trichome phenotype of mutants in the SIAMESE (SIM) gene, which encodes a repressor of endoreplication. Epistasis and overexpression experiments revealed that BLT encodes a key regulator of trichome branching. Additional experiments showed that BLT interacts both genetically and physically with STICHEL, another key regulator of trichome branching. Although blt mutants have normal trichome DNA content, overexpression of BLT results in an additional round of endoreplication, and blt mutants uncouple DNA content from morphogenesis in mutants with increased trichome branching, further emphasizing its role in linking cell shape and endoreplication.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803-1715, USA.
authors.forename: Remmy
authors.initials: R
authors.lastname: Kasili
authors.forename: Cho-Chun
authors.initials: CC
authors.lastname: Huang
authors.forename: Jason D
authors.initials: JD
authors.lastname: Walker
authors.forename: L Alice
authors.initials: LA
authors.lastname: Simmons
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Chris
authors.initials: C
authors.lastname: Faulk
authors.forename: Martin
authors.initials: M
authors.lastname: Hülskamp
authors.forename: John C
authors.initials: JC
authors.lastname: Larkin
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D002454:Cell Differentiation; D048430:Cell Shape; D004261:DNA Replication; D018506:Gene Expression Regulation, Plant; D009024:Morphogenesis; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology; D011003:Ploidies; D016133:Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C559643:BRANCHLESS TRICHOMES protein, Arabidopsis; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C517317:SIAMESE protein, Arabidopsis; C474076:STICHEL protein, Arabidopsis