New Features in Karyotype Structure and Origin of Saffron, Crocus sativus L.

Abstract

Karyotype analyses of saffron, Crocus sativus L., was made using improved routine and C-banding techniques on metaphase plates in root tip cells of 2 accessions from Republic of Azerbaijan and Iran. In the routine technique fixative of Lewitsky and aceto-iron-hematoxylin stain were used. It was established that metaphase chromosomes can be arranged according to their size and morphological features in 8 triplets ranging in size from 11.58±0.13 μm (triplet 1) to 4.57±0.05 μm (triplet 8). Triplets 1 and 2 include subacrocentric, triplets 3, 4 and 8 metacentric and triplets 6 and 7 submetacentric chromosomes. Three chromosomes in each triplet, as a rule, are similar although in some triplets one of them is infrequently distinguishable from the 2 others. Triplet 5 shows an extreme difference so that it always contains 2 kinds of chromosomes: chromosome 5(1) and chromosomes 5(2, 3). Chromosome 5(1) is metacentric (r=1.40) and 6.04±0.13 μm in length, but chromosomes 5(2, 3) are subacrocentric (r=3.49) and noticeably smaller (5.41±0.09 μm). Application of the C-banding technique revealed heterochromatin segments: the sharpest, sharp and week. The sharpest heterochromatin was on telomere of the short arm of chromosome type (triplet) 3 and on proximal part of the long arm of chromosome type 1; a sharp heterochromatin on telomere of the short arms of chromosome types 1, 4 and on the satellites, and a weak heterochromatin on a centromeric region all of 24 chromosomes. Chromosome type 5(1) had a heterochromatin that was a little stronger on the centromeric and, considerably weaker on telomeric regions comparing to those of chromosome type 4. Accessions of saffron from Republic of Azerbaijan and Iran were not significantly distinguishable in karyotype structure. The species C. sativus in its places of cultivation is obviously a clone of one triploid plant originated spontaneously in the nature through crossing between 2 closely related species with participation of n and 2n gametes. Results from statistic analysis and appropriate photographic evidences are provided.