Holokinetic chromosomes of Luzula luzuloides [Juncaceae] in callus culture

A long-term callus culture from Luzula luzuloides leaf meristem subcultured for over one year was examined cytologically. In the control material most of the mitotic cells (95.97%) represented diploid level and standard chromosomes in terms of length (2n = 12AL). Aneuploidy occurred with low frequency (4.03%), with somatic chromosome numbers 2n = 13, 14 resulting from partial agmatoploidy. Karyotype analysis of control material showed differences in chromosome length ranging from 4.94 µm to 3.19 µm in prometaphase, 3.54 µm to 2.54 µm in mid metaphase, and 2.81 µm to 1.88 µm in late metaphase. Callus cells exhibited a wide range of chromosome number variation (2n = 7-48), although a high percentage of cells (61.39%) represented the standard karyotype (2n = 12AL). Variability in chromosome number and karyotype structure was a consequence of chromosome fission (partial and total agmatoploidy), chromosome fusion (partial symploidy) as well as aneusomaty and polyploidy. There was no evident correlation between the frequency of structural and numerical chromosome variation and the duration of callus culture. The cells with modified karyotype appeared in particular collections.