Allotetraploid origin of Allium altyncolicum (Alliaceae, Allium sect Schoenoprasum) as investigated by karyological and molecular markers

The tetraploid Allium altyncolicum (2n = 4x = 32) is considered to be of hybrid origin, because most of its morphological characters are intermediate between those of its putative parents, A. schoenoprasum and A. ledebourianum. In the present work an attempt has been made to ascertain its parentage by several methods: Giemsa C-banding, genomic in situ hybridization (GISH), PCR-RFLP of cpDNA, restriction enzyme mapping of the rDNA, and RAPDs. C-banding and GISH indicates clearly that A. altyncolicum is a segmental allopolyploid. Allium schoenoprasum and A. ledebourianum are the most likely the parental species and the larger part of the genome of A. altyncolicum (26 chromosomes) is derived from A. schoenoprasum. The low genetic divergence between these three species was confirmed by the lack of sequence variation in the ITS sequences of nuclear rRNA genes and of the plastid rbcL-atpB intergenic spacer. Both parental species and A. altyncolicum could be distinguished by RFLP of the rDNA repeats. The geographic origin of the putative parental species was investigated using RAPDs.