Karyotype and B chromosome variation in Lilium amabile Palibin

Abstract

Objective: 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. Methods: 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. Results: 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. Conclusion: 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.