title: Cohesin proteins load sequentially during prophase I in tomato primary microsporocytes.
abstract: Proteins of the cohesin complex are essential for sister chromatid cohesion and proper chromosome segregation during both mitosis and meiosis. Cohesin proteins are also components of axial elements/lateral elements (AE/LEs) of synaptonemal complexes (SCs) during meiosis, and cohesins are thought to play an important role in meiotic chromosome morphogenesis and recombination. Here, we have examined the cytological behavior of four cohesin proteins (SMC1, SMC3, SCC3, and REC8/SYN1) during early prophase I in tomato microsporocytes using immunolabeling. All four cohesins are discontinuously distributed along the length of AE/LEs from leptotene through early diplotene. Based on current models for the cohesin complex, the four cohesin proteins should be present at the same time and place in equivalent amounts. However, we observed that cohesins often do not colocalize at the same AE/LE positions, and cohesins differ in when they load onto and dissociate from AE/LEs of early prophase I chromosomes. Cohesin labeling of LEs from pachytene nuclei is similar through euchromatin, pericentric heterochromatin, and kinetochores but is distinctly reduced through the nucleolar organizer region of chromosome 2. These results indicate that the four cohesin proteins may form different complexes and/or perform additional functions during meiosis in plants, which are distinct from their essential function in sister chromatid cohesion.
authors.affiliation: Department of Biology and Program in Molecular Plant Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO 80523-1878, USA.
authors.forename: Huanyu
authors.initials: H
authors.lastname: Qiao
authors.forename: Leslie D
authors.initials: LD
authors.lastname: Lohmiller
authors.forename: Lorinda K
authors.initials: LK
authors.lastname: Anderson
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D020090:Chromosome Segregation; D018551:Solanum lycopersicum / Q000166:cytology*; D008540:Meiosis; D049469:Meiotic Prophase I; D011058:Pollen / Q000378:metabolism*; D012854:Sister Chromatid Exchange; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D000097722:Cohesins