Comparative Genomics of A Rice Centromere

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

The centromere is a cytologically (visually) defined entity with highly conserved functions. It is responsible for chromosomal sister chromatid cohesion and is the site for the assembly of kinetochore, a protein structure which links chromosomes to spindle fibers during cell division. In most multicellular eukaryotes, the centromeres are embedded within heterochromatin, a tightly packed form of DNA, and are associated with long tracts of satellite repeats in which genes are largely absent. Thus, the centromere is traditionally viewed as a highly heterochromatic and genetically silent chromosomal domain. Recent research work from the centromere of rice chromosome 8 (Cen8) as well as the neocentromeres (newly forming centromeric regions) from humans suggest that centromeres originated from genic regions. This project will focus on centromere evolution using rice Cen8 as a model. Specifically, this project will develop bacterial artificial chromosome (BAC)-based physical maps that span Cen8 in six diploid wild rice species and produce approximately one megabase of DNA sequence from each of the six centromeres. The functional boundary of the six centromeres will be determined using cytogenetic and molecular methods. The structural rearrangements and sequence divergence associated with the six centromeres will be revealed by comparative sequence analysis. Expression and evolution of Cen8-associated genes will be explored to understand how such genes adapt to a unique chromosomal domain. The results from this project will shed light on centromere evolution and will also build a foundation to study the evolution of genes located in heterochromatic and recombinationally-suppressed chromosomal domains. Access to Project Outcomes Sequence data and gene annotation results will be made available to the public through GenBank, the project website (accessible through http://www.omap.org/) and community databases such as Gramene (http://www.gramene.org).