Karyotype and B chromosome variation in Lilium amabile Palibin

Lilium amabile Palibin (2n = 2x = 24) is an endemic lily species in Korea. B chromosomes are supernumerary chromosomes and the presence of B chromosome in L. amabile was known by previous researches. The current research was conducted to characterize the genetical and cytological features of the B chromosome plants in L. amabile.

Karyotype and B chromosome cytotype analyses were carried out among 135 L. amabile accessions that were collected from six geographical locations in Korea using conventional aceto-carmine staining as well as FISH technique with ribosomal RNA gene probes.

The karyotype of L. amabile genome consisted of two large metacentric, four intermediate subtelocentric, and six intermediate to small acrocentric chromosomes in which chromosomes 1, 6 and 7 carried the 45S rRNA gene loci and chromosome 3 carried the 5S rRNA gene. There were 4 types of B chromosomes, two large B chromosomes and two small B chromosomes. The ribosomal RNA gene loci were not present in the B chromosomes. The 135 accessions were classified into 13 cytotypes including diploids and different B chromosome aneuploids. Among the aneuploids, the most frequent cytotype was 24 + 1B, which was followed by 24 + 2B, 24 + 1b, 24 + 1B + 2b, 24 + 1B + 4b, and 24 + 2B + 4b.

The karyotype of L. amabile was consistent with other species in the genus Lilium without polyploids. The B chromosome cytotypes were highly variable and the occurrences of different cytotypes were random among the six populations, implying that the B and b chromosome occurrence was random in each population.