ARS | Publication request: Genome-Wide Sequence Comparison of Centromeric Regions and BAC-Landing on Chromosomes Provide New Insights into Centromere Evolution Among Wheat, Brachypodium, and Rice

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 6, 2009
Publication Date: January 9, 2010
Repository URL: http://www.intl-pag.org/18/abstracts/P05a_PAGXVIII_236.html
Citation: Qi, L., Friebe, B., Gu, Y.Q., Qian, C., Gill, B.S. 2010. Genome-Wide Sequence Comparison of Centromeric Regions and BAC-Landing on Chromosomes Provide New Insights into Centromere Evolution Among Wheat, Brachypodium, and Rice. Plant and Animal Genome XVIII Conference, January 9-13, 2010, San Diego, CA. P236. Available: http://www.intl-pag.org/18/abstracts/P05a_PAGXVIII_236.html

Technical Abstract: As an emerging model system, the nearly finished sequence of Brachypodium distachyon will provide new insights into comparative and functional genomics of grass species. However, centromeres of B. distachyon are unlikely to be sequenced and assembled precisely similar to many other sequenced organisms because of their highly repeated structure. Three independent but complementary approaches were pursued to study centromeric region homologies among the chromosomes of wheat, Brachypodium, and rice. The genes present in pericentromeres of the basic set of seven chromosomes of wheat and the Triticeae, and the 80 rice centromeric genes spanning the CENH3 binding domain of centromeres 3, 4, 5, 7, and 8 were used as "anchor" markers to identify centromere locations in the B. distachyon chromosomes. Fifty-three B. distachyon BAC clones anchored by wheat pericentromeric ESTs were used as probes for BAC-FISH analysis of B. distachyon mitotic chromosomes. Integrated sequence alignment and BAC-FISH data were used to define the five possible centromere regions of B. distachyon corresponding to four wheat and five rice centromere regions. The following syntenic relationships of centromeres were evident for Brachypodium (Bd), wheat (W) and rice (R): Bd1-W2-R7, Bd2-W1-R5, Bd3-W7-R8, Bd4-W4-R11, and Bd5-R4. The positions of 30.2 Mb in chromosome Bd2, 19.5 Mb in Bd3, and 22.5 Mb in Bd4 may represent the core centers of centromeres for these three chromosomes. Five B. distachyon centromeres were traced back to the centromeres of the five ancestral chromosomes of grass genomes. This investigation provides a platform for studying the centromere evolution of grass genomes.