Disruption of the Arabidopsis SMC4 gene, AtCAP-C, compromises gametogenesis and embryogenesis.
In higher eukaryotes, the condensin complex is a multisubunit apparatus that plays a pivotal role in the coordinated condensation of chromatin during mitosis. The catalytic subunits, CAP-E and CAP-C, members of the SMC family of ATPases, form a heterodimer, the activity of which is controlled by the non-SMC subunits CAP-D2, CAP-G and CAP-H. Here, we report the characterization of a T-DNA insertion mutant of the Arabidopsis CAP-C gene. Analysis of the progeny of selfed heterozygotes revealed that the homozygous null genotype is embryo lethal, with arrest occurring at or before the globular stage of development. Patterning defects associated with altered planes of cytokinesis were found in both the embryo and the suspensor. Crosses of heterozygotes with wild type plants revealed both male and female gametophytic defects. Stretched chromatin was observed between segregating mitotic chromosomes in pollen produced by selfed heterozygotes. Additionally, some plants heterozygous for the T-DNA insertion exhibited loss of apical dominance and mild fasciation, indicating a semi-dominant effect of the mutation. These results reveal a critical role for AtCAP-C during cell division and, unlike our previous studies on the AtCAP-E genes, suggest that no redundant factors for AtCAP-C exist in the Arabidopsis genome.
Department of Botany, Division of Life Sciences, University of Toronto, 1265 Military Trail, M1C 1A4, Scarborough, ON, Canada.
Najeeb U
NU
Siddiqui
Stefan
S
Rusyniak
Clare A
CA
Hasenkampf
C Daniel
CD
Riggs
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology*; D005718:Gametogenesis / Q000502:physiology*; D015870:Gene Expression; D017343:Genes, Plant; D006579:Heterozygote; D005810:Multigene Family; D046912:Multiprotein Complexes / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D010641:Phenotype; D011058:Pollen / Q000254:growth & development
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C108312:condensin complexes; D000251:Adenosine Triphosphatases; C513213:CAP-C protein, Arabidopsis