Genes mapping in the functional centromere of the wheat chromosomes.

摘要

Centromeric regions of wheat chromosomes are usually heterochromatic and believed to be inactive for gene expression. We have identified two wheat group 1 genes that seem to be expressing from the chromosomal regions around centromere. On chromosome 1A and ID of Chinese Spring, these genes are present on the short arm, very close to the centromere. On chromosome IB, however, these genes map in the centromere, as both ditelo IBL and IBS contain the genes. For both genes, there is only one structural copy on each of the three homoeologs. But the band intensity in the B genome is more in both Chinese Spring and Pavon ditelosomic IBL lines suggesting deletion specific duplication of sequences containing PSR161 in these lines. The deletion specific duplications were not resolved using ten different restriction enzymes indicating that the region duplicated is very large. Alternatively, this may be due to the presence of multiple copies of an extra mini chromosome carrying the region. Sequence analysis ofPSR161 with wheat ESTs revealed that centromeric copy of the gene is actively expressing.