BIN4, a novel component of the plant DNA topoisomerase VI complex, is required for endoreduplication in Arabidopsis.
How plant organs grow to reach their final size is an important but largely unanswered question. Here, we describe an Arabidopsis thaliana mutant, brassinosteroid-insensitive4 (bin4), in which the growth of various organs is dramatically reduced. Small organ size in bin4 is primarily caused by reduced cell expansion associated with defects in increasing ploidy by endoreduplication. Raising nuclear DNA content in bin4 by colchicine-induced polyploidization partially rescues the cell and organ size phenotype, indicating that BIN4 is directly and specifically required for endoreduplication rather than for subsequent cell expansion. BIN4 encodes a plant-specific, DNA binding protein that acts as a component of the plant DNA topoisomerase VI complex. Loss of BIN4 triggers an ATM- and ATR-dependent DNA damage response in postmitotic cells, and this response coincides with the upregulation of the cyclin B1;1 gene in the same cell types, suggesting a functional link between DNA damage response and endocycle control.
Department of Cell and Developmental Biology, John Ines Centre, Norwich NR4 7UH, United Kingdom.
Christian
C
Breuer
Nicola J
NJ
Stacey
Christopher E
CE
West
Yunde
Y
Zhao
Joanne
J
Chory
Hirokazu
H
Tsukaya
Yoshitaka
Y
Azumi
Anthony
A
Maxwell
Keith
K
Roberts
Keiko
K
Sugimoto-Shirasu
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D064007:Ataxia Telangiectasia Mutated Proteins; D060406:Brassinosteroids; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002777:Cholestanols / Q000378:metabolism; D003078:Colchicine / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D016195:G2 Phase / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D008938:Mitosis / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009929:Organ Size / Q000187:drug effects; D010641:Phenotype; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D011003:Ploidies; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D013260:Steroids, Heterocyclic / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D018797:Cell Cycle Proteins; D002777:Cholestanols; D004268:DNA-Binding Proteins; D013260:Steroids, Heterocyclic; D025521:Tumor Suppressor Proteins; D004247:DNA; C576892:ATR protein, Arabidopsis; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C526975:Bin4 protein, Arabidopsis; D004264:DNA Topoisomerases, Type I; D003078:Colchicine; C023623:brassinolide