Poster: Reproductive Development

Abs # 465: The Arabidopsis cohesin proteins play essential roles in mitosis and meiosis

Presenter:	Makaroff, Chris A., makaroca@muohio.edu
Authors	Makaroff, Chris A. (A)   Xue, Cai  (A)   Xia, Ming  (A)   Lam, Wing See  (A)   Liu, Zhe  (A)
Affiliations:	(A): Department of Chemistry and Biochemistry Miami University

The faithful transmission of chromosomes during mitosis and meiosis requires the establishment and subsequent release of cohesion between replicated chromosomes. Sister chromatid cohesion is mediated in large part by the cohesin complex, which consists of four highly conserved proteins: SMC1, SMC3, SCC1/REC8 and SCC3. Our laboratory is currently investigating the Arabidopsis cohesin proteins to better understand their roles in plants. Inactivation of SYN1 results in defects in meiotic chromosome arm cohesion as early as interphase while centromere cohesion is maintained until approximately anaphase I. SYN1 localizes to arms of meiotic chromosomes from approximately meiotic interphase to anaphase I, confirming that SYN1 is the Arabidopsis REC8 homologue. Results from studies to further investigate the role of SYN1 in homologous chromosome pairing during meiosis will be presented. Three additional SCC1/REC8 homologues (SYN2, SYN3 and SYN4) have been isolated and are being characterized. SYN3 appears to have a novel role in the plant nucleolus, while SYN2 and SYN4 participate in mitosis. Results from immunolocalization experiments and the analysis of syn2, syn3 and syn4 mutant plants will be presented. We have also isolated and characterized AtSMC1 and AtSMC3. Antibody to AtSMC3 strongly labels meiotic chromosomes from interphase to diakinesis at which time most of the protein relocalizes to the spindles until late telophase II. Finally AtSMC3 RNAi plants have been generated and are being analyzed in order to circumvent difficulties associated with the embryo-lethality observed in SMC1 and SMC3 plants. Results for these studies will also be presented.