Chromosome cohesion plays a central role in chromosome segregation during both cell division and sexual reproduction. In addition to controlling sister chromatid cohesion, cohesin proteins are critical for recombination, chromosome structure and stability, the repair of DNA lesions and may help control gene expression. Therefore, cohesin proteins are essential for the viability of organisms. The goal of this project is to better understand how sister chromatid cohesion is regulated during sexual reproduction in plants and to investigate novel aspects of sister chromatid cohesion. Studies in yeast and animal systems have provided information on the overall structure of the cohesin complex as well as insights into how cohesin is established and removed. Most aspects of the structure and regulation of cohesin complexes are conserved. However, novel aspects have been identified in some species and these are providing important new insights into how this essential process is regulated. For example, Arabidopsis contains an alpha-kleisin (SYN3) that is preferentially localized in the nucleolus, suggesting it has evolved a specialized role in controlling ribosomal DNA (rDNA) structure and/or expression. Likewise, SWI1 is a plant-specific protein that is required to establish cohesion during meiosis. Experiments outlined in this project will determine how SYN3 functions in controlling rDNA structure, and elucidate how plants establish sister chromatid cohesion by determining the role(s) of SWI1 and CTF7 in meiosis. Results from experiments in the model organism Arabidopsis will provide new insights and expand our knowledge of sister chromatid cohesion and the proteins involved in this essential process. Studies on chromosome cohesion in plants have many important implications for plant breeding and improving agricultural practices. This project will help train a number of future scientists at the postdoctoral, graduate and undergraduate levels, including students underrepresented in the physical sciences who will participate in independent research projects associated with this project.
