Morphological characteristics and fish analysis of hibiscus f₁ hybrids and parental lines

In this study, the characteristics of ‘Tohagolred’, ‘Daewangchun’ generated by a reciprocal cross between Hibiscus sinosyriacus ‘Seobong’ and H. syriacus ‘Samchully’, and the corresponding parental lines were investigated and DNA content was measured by flow cytometry. FISH detection of 5S and 45S rDNA was conducted to analyze the parental and progeny karyotypes. The leaf margin was serrate for ‘Samchully’ and crenate for ‘Seobong’. The leaf margin of ‘Daewangchun’ was crenate, the avarage leaf length was 8.2 cm, and the average leaf width was 5.4 cm. The leaf margin of ‘Tohagolred’ was crenate, the average leaf length was 7.2 cm, and the average leaf width was 5.7 cm. The diameter of the ‘Daewangchun’ flower was 13.8 cm, which was 2 cm larger than the parents, and the red eye radius was 2.1 cm, which was approximately 1 cm larger than that of the parents. ‘Daewangchun’ appeared pink in color, similar to ‘Samchully.’ The flower diameter of ‘Tohagolred’ was 12.6 cm, which was 1 cm larger than that of the parents; the red eye length radius was 1.1 cm and approximately 1 cm smaller than that of the parents. ‘Tohagolred’ also appeared pink in color, similar to ‘Samchully.’ The DNA content was 1928.77 Mbp/1C (1.97 pg/1C) for ‘Seobong’ and 2820.34 Mbp/1C (2.88 pg/1C) for ‘Samchully’. Moreover, the DNA content of ‘Daewangchun’ and ‘Tohagolred’ was 1975.88 Mbp/1C (2.88 pg/1C) and 1914.70 Mbp/1C (1.97 pg/1C), respectively. DAPI staining showed that ‘Seobong’ was 2n = 80 and ‘Samchully’ was 2n = 126 as parents. However, Hibiscus F₁ cultivars ‘Daewangchun’ and ‘Tohagolred’ were 2n = 82. FISH analysis revealed that ‘Seobong’ had six 45S rDNA signals and two 5S rDNA signals. In contrast, ‘Samchully’ had six 45S rDNA signals and three 5S rDNA signals. Both ‘Daewangchun’ and ‘Tohagolred’ had seven 45S rDNA signals and two 5S rDNA signals. These results provide a foundation for genetic analysis and cultivation of new crops of Hibiscus spp.