CHROMOSOME-BANDING AND GENOME SIZE DIFFERENTIATION IN PROSPERO (HYACINTHACEAE) - DIPLOIDS

Prospero is a Mediterranean autumn-flowering genus of Hyacinthaceae co mmonly classified in Scilla as S. autumnalis and S. obtusifolia. Exten sive dysploid and polyploid variation has been reported. In the presen t study 77 diploid accessions from the western to the eastern part of the area of distribution, the major part being from continental Greece and Crete, have been analysed for karyotype structure and, in part, f or genome size. Methods employed were acetocarmine staining, Giemsa C- banding, fluorochrome staining mainly with chromomycin A(3)/DAPI, silv er impregnation, and Feulgen densitometry. Banded idiograms were estab lished with a computer assisted karyotype analysis procedure. Chromoso me numbers were 2n = 8 in P. obtusifolium, and 2n = 12 and 14 in P. au tumnale s. 1. Dispensable euchromatic chromosome segments and differen t types of B chromosomes occurred. Among the cytotypes with 2n = 14 tw o karyotypes from Turkey differed from each other and from the rest in form, position of the nucleolar constriction, and in genome size. The remaining accessions were similar in karyotype shape but three levels of genome size could be discerned, the highest (1C = 7.50 pg) being f ound on the Iberian Peninsula, an intermediate one on Corsica and Malt a, and the lowest (4.27 pg) in the Aegean. The karyotype with 2n = 12 had an intermediate genome size, and that of P. obtusifolium a relativ ely low one. Heterochromatin amount was generally low, but some karyot ypes showed characteristic banding patterns. The relationship between the chromosome complements with 2n = 14, 12 and 8 is discussed on the basis of idiograms and DNA amounts.