MOLECULAR CYTOGENETICS OF ALSTROEMERIA - IDENTIFICATION OF PARENTAL GENOMES IN INTERSPECIFIC HYBRIDS AND CHARACTERIZATION OF REPETITIVE DNAFAMILIES IN CONSTITUTIVE HETEROCHROMATIN

The genus Alstroemeria consists of diploid (2n=2x=16) species originat ing mainly from Chile and Brazil. Most cultivars are triploid or tetra ploid interspecific hybrids. C-banding of eight species revealed obvio us differentiation of constitutive heterochromatin within the genus. T he present study focused on the molecular (cyto)genetic background of this differentiation. Genomic slot-blot analysis demonstrated strong c onservation of major parts of the genomes among six species. The chrom osomes of A. aurea and A. ligtu, species with pronounced interstitial C-bands, were found to contain large amounts of highly repetitive and species-specific DNA. The variation in size, number and intensity of s trongly probed bands of major repetitive DNA families observed in geno mic Southern blots of Sau3A, HaeIII, and Msel digests indicated a stro ng correlation between variation in genomic DNA composition and differ ent C-banding patterns among Alstroemeria species. Genomic in situ hyb ridization (GISH) revealed a clear distinction between parental chromo somes in the hybrids between Chilean and Brazilian species and also be tween Chilean species, as long as at least one of the parental species possessed prominent C-banding. Regarding the latter, discriminative h ybridization resulted from highly repetitive species specific DNA in t he heterochromatic chromosome regions of A. aurea and A. ligtu, and ca used GISH banding patterns that coincided with the C-banding patterns.