A molecular-cytogenetic method for locating genes to pericentromeric regions facilitates a genomewide comparison of synteny between the centromeric regions of wheat and rice.
Centromeres, because of their repeat structure and lack of sequence conservation, are difficult to assemble and compare across organisms. It was recently discovered that rice centromeres often contain genes. This suggested a method for studying centromere homologies between wheat and rice chromosomes by mapping rice centromeric genes onto wheat aneuploid stocks. Three of the seven cDNA clones of centromeric genes from rice centromere 8 (Cen8), 6729.t09, 6729.t10, and 6730.t11 which lie in the Cen8 kinetochore region, and three wheat ESTs, BJ301191, BJ305475, and BJ280500, with similarity to sequences of rice centromeric genes, were mapped to the centromeric regions of the wheat group-7 (W7) chromosomes. A possible pericentric inversion in chromosome 7D was detected. Genomewide comparison of wheat ESTs that mapped to centromeric regions against rice genome sequences revealed high conservation and a one-to-one correspondence of centromeric regions between wheat and rice chromosome pairs W1-R5, W2-R7, W3-R1, W5-R12, W6-R2, and W7-R8. The W4 centromere may share homology with R3 only or with R3 + R11. Wheat ESTs that mapped to the pericentromeric region of the group-5 long arm anchored to the rice BACs located in the recently duplicated region at the distal ends of the short arms of rice chromosomes 11 and 12. A pericentric inversion specific to the rice lineage was detected. The depicted framework provides a working model for further studies on the structure and evolution of cereal chromosome centromeres.
Qi
Lili
L
Wheat Genetic and Genomic Resources Center, Department of Plant Pathology, Kansas State University, Manhattan, Kansas 66506-5502, USA.
Friebe
Bernd
B
Zhang
Peng
P
Gill
Bikram S
BS
D000782:Aneuploidy; D002503:Centromere / Q000235:genetics*; D002874:Chromosome Mapping / Q000379:methods*; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D019295:Computational Biology; D020732:Cytogenetic Analysis / Q000379:methods*; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags / Q000378:metabolism; D017343:Genes, Plant / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D012275:Oryza / Q000166:cytology / Q000235:genetics*; D020161:Physical Chromosome Mapping; D012689:Sequence Homology, Nucleic Acid; D026801:Synteny / Q000235:genetics*; D014908:Triticum / Q000166:cytology / Q000235:genetics*