AtCTF7 is required for establishment of sister chromatid cohesion and association of cohesin with chromatin during meiosis in Arabidopsis

Background: The establishment of sister chromatid cohesion followed by its controlled release at the metaphase to anaphase transition is necessary for faithful segregation of chromosomes in mitosis and meiosis. Cohesion is established by the action of Ctf7/Eco1 on the cohesin complex during DNA replication following loading of cohesin onto chromatin by the Scc2-Scc4 complex. Ctf7 is also required for sister chromatid cohesion during repair of DNA double strand breaks. Ctf7 contains an acetyltransferase domain and a zinc finger motif and acetylates conserved lysine residues in the Smc3 subunit of cohesin. In Arabidopsis CTF7 is encoded by a single gene and mutations in AtCTF7 cause embryo lethality indicating that the gene is essential. Results: To study the function of Ctf7 in plants and to determine its role in sister chromatid cohesion, we constructed a conditional allele of AtCTF7 in Arabidopsis using an inducible RNA interference (RNAi) strategy, so as to avoid the embryo lethality caused by mutations in AtCTF7. We found that induction of RNAi against AtCTF7 caused severe inhibition and defects in growth during vegetative and reproductive stages as well as sterility. AtCTF7-RNAi plants displayed chromosome fragmentation and loss of sister chromatid cohesion during meiosis. Immunostaining for the cohesion subunit AtSCC3 showed a marked reduction in association of cohesin with chromatin during meiosis in AtCTF7-RNAi plants. Conclusions: We find that AtCTF7 is essential for sister chromatid cohesion during meiosis in Arabidopsis and is required for association of cohesin with chromatin in prophase of meiosis.