Phenotypic characterization and cytogenetic analysis of interspecific L. longiflorum x L. hansonii hybrids and their mitotic assessment

초록

The objectives of this study were to develop novel interspecific hybrid lines and to investigate the floral morphology, chromosomal attributes, and mitotic division of the hybrid progenies. Following a cut-style procedure in diploid Lilium longiflorum and Korean native L. hansonii, for the first time, the first interspecific hybrid progenies were successfully obtained by in vitro embryo rescued. Their phenotypic, molecular cytogenetics and miotic assessment were observed using a genomic in situ hybridization methodology. Combination of the phenotypic characters from both parents were recognized in all the hybrid lines. FISH results revealed, on distinct chromosomes, female parent L. longiflorum and male parent L. hansonii showed six and 16 18S rDNA, while four sets of F-1 showed nine, ten, ten, and 11 18S rDNA, respectively. In all the F-1 progenies and their parents, single pair of 5S rDNA was found. GISH results revealed Lilium longiflorum and Lilium hansonii contributed equally to their interspecific hybrids. In Lilium breeding, chromosome recombination in F-1 interspecific hybrids become a new phenomenon. In this study, GISH analysis of F-1 hybrids revealed four recombinant sites, including two M/L and two L/M recombinant chromosomes, indicating a significant genetic relationship between the two species. In L. longiflorum and L. hansonii, two different types of cell divisions in the fertilized zygote cell have been seen in different days following the pollination. Chromosomal recombination with univalent and bivalent pair of chromosomes was identified from the early metaphase stage of the pollinated egg cell during the first division, which has not been reported in interspecific F-1 progenies yet, despite the frequency being around 3%. In conclusion, the mitotic assessment of L. longiflorum x L. hansonii fertilized single zygote cell indicates an earlier chromosomal introgression and a strong genetic relationship between the two species.

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