Variable karyotype with B-chromosomes in Bellevalia saviczii (Liliaceae)

Bellevalia saviczii (Liliaceae), a hexaploid (2n = 6x = 24), was collected from mountain slopes in the Shiraz valley, southern Iran. The basic karyotype consists of one long metacentric chromosome, a slightly shorter acrocentric, and two shorter submetacentrics. In 32% of the plants, one and sometimes two of the acrocentrics (IIa) appeared with a pericentric inversion that changed it into a metacentric (IIm). This metacentric IIm was present in a Hardy-Weinberg ratio throughout the collection range of more than 300 km. A number of aneuploids were found, pentasomics [2n - 1 = 23 (4.9%)], heptasomics [2n + 1 = 25 (2.5%)], and one octasomic [2n + 2 = 26 (0.3%)]. Re-assorted karyotypes with 2n = 24, but with odd numbers of two of the chromosomes, were also present (6.6%). B-chromosomes were found in root meristems and in pedicels in a number (19.1%) of the plants that grew around a 30 km marsh. Their numbers ranged from 1B to 8Bs per plant peaking in the 2B mode. The B-chromosomes (two polymorphs with terminal and near-terminal sticking points) were telocentric with a few metacentric iso-Bs. No B-carrying plants were found in the drier regions away from the marsh. The B-frequency distribution for aneuploids and pericentric inversions was much different than for the standard euploid.