Polymorphism of heterochromatic regions of flax chromosomes

Flax chromosomes (Linum usitatissimum L., 2n = 30) were analyzed using C-ba nding technique. Irrespective of small sizes (1,5-3,5 mum), all 15 pairs of homologous chromosomes were identified according to specific C-banding pat terns and their morphology. Heterochromatic bands were located predominantl y in pericentromeric regions of flax chromosomes. Idiogram of metaphase C-b anded chromosomes of L. usitatissimum I,. was presented. Since the C-band s izes depended on chromosome length, the analysis of the heterochromatic reg ion polymorphism was performed on chromosomes in middle metaphase, when the C-bands reached the maximum sizes. C-banding polymorphism was investigated in karyotypes bf three flax samples: L. usitatissimum L., accession K-603 (L.; usitatissimum var. usitatissimum) and accession K-594 (L. usitatissimu m var. humile (Mill.)). The general C-banding patterns of chromosomes were observed in karyotypes of all investigated forms. However, intraspecific si ze variation of heterochromatic regions was revealed. According to the C-ba nding patterns the karyotype of fiber flax (accession K-603) was very simil ar to that of L. usitatissimum L., although the sizes of some intercalary a nd telomeric bands were slightly larger. In addition to this, the NOR on ch romosome I was more clearly expressed in the karyotype of K-603. The chromo somes of crown flax (accession K-594) had smaller pericentromeric heterochr omatic regions and larger intercalary C-bands. in contrast to karyotype oft . usitatissimum L: most crown flax chromosomes had pronounced telomeric C-b ands. Thus, the C-banding markers can be used as well as molecular ones to investigate intraspecific genetic polymorphism of L, usitatissimum L.