Visualization of genomic relationships in allotetraploid hybrids between Chrysanthemum lavandulifolium X C. chanetii by fluorescence in situ hybridization and genomic in situ hybridization

Abstract

Artificial cross between Chrysanthemum lavandulifolium (2n=18 diploid) and C. chanetii (2n=36, tetraploid) made succesfully interspecific F₁ hybrid (2n=36 tetraploid instead of 2n=27 tripolid) for the first time. The F₁ hybrid had 12 signals of 45S rDNA and and four signals of 5S rDNA by FISH. The chromosome complement of the F₁ hybrid showed each set of the both parental chromosomes by GISH by using the biotin labeled probe of C. lavandulifolium mixed with approximately 20X blocking DNA of C. chanetii. Eighteen yellow-green colored chromosomes were hybridized with the probe of C. lavandulifolium, that could be involved with C. lavandulifolium, while the other 18 orange-red colored chromosomes were not GISH-hybridized chromosomes with the probe, that could be involved with C. chanetii. The extra nine chromosome set in the hybrids might be resulted due to duplication of the haploid chromosome set of C. lavandulifolium at/after fertilization.