Expression of epitope-tagged SYN3 cohesin proteins can disrupt meiosis in Arabidopsis.

α-kleisins are core components of meiotic and mitotic cohesin complexes. Arabidopsis contains genes encoding four α-kleisins. SYN1, a REC8 ortholog, is essential for meiosis, while SYN2 and SYN4 appear to be SCC1 orthologs and function in mitosis. SYN3 is enriched in the nucleolus of meiotic and mitotic cells and is essential for megagametogenesis. It was recently shown that expression of SYN3-RNAi constructs in buds cause changes in meiotic gene expression that result in meiotic alterations. In this report we show that expression of SYN3 from the 35S promoter with either a c-terminal Myc or FAST tag causes a reduction in SYN1 mRNA levels that results in alterations in sister chromatid cohesion, homologous chromosome synapsis and synaptonemal complex formation during both male and female meiosis.