Rapid genome reshuffling induced by allopolyploidization in F1 hybrid in Chrysanthemum remotipinnum (formerly Ajania remotipinna) and Chrysanthemum chanetii (formerly Dendranthema chanetii)

Abstract

Allopolyploidization was investigated in an artificial F1 hybrid between Chrysanthemum remotipinnum (2n=18) and Chrysanthemum chanetii (2n=36). Homoeologous and non-homologous chromosomes could pair in the PMC of the hybrid that showed complex pairings and configurations at diakinesis. Physical maps of the 5S and 45S rDNA genes were generated by fluorescence in situ hybridization (FISH) for the F1 hybrid that had four signals of the 5S rDNA sites in four median-centromeric chromosomes and were different from that of C. remotipinnum, which had four signals in two median-centromeric chromosomes. The hybrid did not show any of the double signals 5S rDNA like C. remotipinnum did. FISH signals of 45S rDNA showed that the hybrid had eight signals of the 45S rDNA sites and seemed to keep the four signals of C. remotipinnum. Genomic in situ hybridization (GISH) distinguished respective parental chromosomes in the F1 hybrid chromosome complement and showed that approximately 18-yellow-colored chromosomes were hybridized with the probe of C. remotipinnum while the other 18 red-colored chromosomes that were not hybridized could be of C. chanetii. GISH detected translocations at different chromosomal sites and duplication exists in the maternal genome side.