Unstability of Genomic Constitution of Polyploid Oats (genus Avena)

摘要

Genomic differentiation with chromosomal rearrangement in oats was analyzed by FISH technique using total genomic DNA of A. eriantha (CC) and 18S-5. 8S-26S rDNA as probe. Most of the chromosome rearrangements were observed in both tetraploid (AACC) and hexaploid (AACCDD) oats involving segments of C-genome chromosomes translocated onto A- or A/D-chromosomes. Novel C-genome translocation segments were detected in synthesized polyploid lines. It suggests that the C-genome chromosomes are flexible for translocation and C-genome het-erochromatin is tend to be transferred to the terminal regions of the other genome chromosomes in processes of producing amphiploid oats by colchicine treatment. In addition, no 18S-5.8S-26S rDNA signals were observed on C-genome chromosome in all allopolyploid species. The rDNA sites were also recognized mainly in A-genome by Southern analysis of A. canariensis (AA) and A. agadiriana (AABB). From the above, the behavior of C-genome chromosomes detected in our study would be the cause of genomic differentiation in allopolyploid oats including central A-genome. Consequently, the diploid-like pairing as well as disomic inheritance mode in all the hexaploid oats would be explained by the above translocations of C-genome chromosomes, which played the important role in the diversity of oats.