KARYOTYPE ANALYSIS AND THE DISTRIBUTION OF CONSTITUTIVE HETEROCHROMATIN IN 5 SPECIES OF PINUS

A karyological study on 5 species os Pinus [P. koraiensis, P. strobus, P. nigra, P. resinosa and P. banksiana] (2n = 24) revealed a major difference in the distribution of C[constitutive]-heterochromatin between the 2 subgenera Pinus and Strobus. Pericentromeric C-heterochromatin was present only in the subgenus Pinus. All 5 species contained distally located C-heterochromatin with 6-10 intercalary C-bands/genome. These intercalary C-bands were observed as a single narrow band restricted to 1 arm of a banded chromosome; the exception was P. strobus, which showed 1 chromosome with 2 C-bands, 1 in each chromosome arm. Intraspecific differences in the distribution of the C-heterochromatin were sufficient to distinguish all 5 species studied on the basis of their C-banded karyotypes. A comparison of the distribution of C-heterochromatin and the location of secondary constrictions demonstrated that all intercalary C-bands were located at secondary constrictions.