Location: Dairy Forage ResearchTitle: Amplification and adaptation of satellite repeats in the centromeres of polyploid switchgrass species
|YANG, XUEMING - University Of Wisconsin|
|ZHAO, HAINAN - Michigan State University|
|ZHANG, TAO - Michigan State University|
|ZENG, ZIXIAN - Michigan State University|
|ZHANG, PINGDONG - Michigan State University|
|ZHU, BO - Michigan State University|
|HAN, YONGHUA - Michigan State University|
|BRAZ, GUILHERME - Michigan State University|
|SCHMUTZ, JEREMY - Joint Genome Institute|
|JIANG, JIMING - Michigan State University|
Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2018
Publication Date: 3/23/2018
Citation: Yang, X., Zhao, H., Zhang, T., Zeng, Z., Zhang, P., Zhu, B., Han, Y., Braz, G., Casler, M.D., Schmutz, J., Jiang, J. 2018. Amplification and adaptation of satellite repeats in the centromeres of polyploid switchgrass species. New Phytologist. 218:1645-1687.
Interpretive Summary: Switchgrass is an important species that is serving as a genetic model for development of dedicated biomass crops for conversion to energy. Genomic research on the function and structure of chromosomes is critical to support breeding and selection efforts to improve switchgrass biomass production. Every chromosome has one centromere, the point of attachment when chromosomes pair up with each other during cell division. An analysis of DNA sequence information within all 18 switchgrass centromeres indicated sequence patterns that are similar to other grasses. Most centromeres are characterized by multiple-repeat motifs, indicating the usual functions found in other grasses. However, one chromosome contained a centromere with an unusual DNA sequence that appears similar to 5s rDNA, which functions in the translation of DNA to proteins in plant cells. All sequence information will be made available to readers and researchers for use in tagging centromeres as an aid to additional in-depth genomic studies of switchgrass.
Technical Abstract: Centromeres in most higher eukaryotes are composed of long arrays of a single satellite repeat, which occupies every centromere and does not spread out of the centromeric regions. Why centromeres are dominated by satellite repeats and how the satellite repeats originate and evolve are among the long-standing questions in centromere biology. We conducted a genome-wide analysis of DNA sequences associated with centromeric nucleosomes in switchgrass (Panicum virgatum). We identified eight satellite repeats that are distributed in different centromeres. Seven of these repeats showed classical characteristics associated with satellite repeats, with monomeric lengths ranging from 166 to 189 bp. These repeats share a 80-bp DNA motif that is conserved in several centromeric repeats reported in distantly related grass species. We demonstrated that the 80-bp related regions may dictate translational and rotational phasing of several centromeric switchgrass centromeric repeats with the centromeric nucleosomes. Surprisingly, the last centromeric repeat, Pv156, was identical to the 5S ribosomal RNA genes, which were recruited to be the centromere of one of the switchgrass chromosomes. These results shed new insight on adaptation of satellite repeats in functional centromeres.