I. Lindelaursen et C. Baden, GIEMSA C-BANDED KARYOTYPES OF 2 CYTOTYPES (2X, 4X) OF PSATHYROSTACHYS-LANUGINOSA (POACEAE, TRITICEAE), Hereditas, 120(2), 1994, pp. 113-120
The karyotypes of the diploid (2n = 2x = 14) and tetraploid (2n = 4x =
28) cytotypes of the outbreeding P. lanuginosa collected from one pop
ulation in China were investigated by Giemsa C- and N-banding and AgNO
3 staining. The complement of the diploid consisted of 14 large chromo
somes: 8 metacentrics and 6 SAT-chromosomes, one metacentric and 2 sub
metacentric pairs, with small to minute, polymorphic, completely heter
ochromatic satellites. Except that only eight SAT-chromosomes were obs
erved, the complement of the tetraploid matched a doubling of that of
the diploid and indicated an autoploid origin. The existence of 12 chr
omosomes with nucleolus organizers was established through AgNO3 stain
ing demonstrating nucleoli. C-banding patterns comprised from zero to
three (2x), or four (4x) small bands per chromosome giving a low conte
nt of constitutive heterochromatin ( < 3 %). The level of banding patt
ern polymorphism was low. N-banding produced no bands. Variation in th
e size of nucleoli demonstrated a differential nucleolus forming capac
ity of nucleolus organizers among SAT-chromosomes. The basic karyotype
was similar to those of P. fragilis, P. juncea and P. stoloniformis,
indicating a close relationship and the presence of genome N. Meiotic
analysis suggested the presence of a chromosomal rearrangement in the
diploid. The frequency of interstitial chiasmata was high. Differences
in pollen diameters differentiated the two cytotypes.