Tandem repeats belonging to three DNA sequence families ( OeTaq80, OeTaq178, and OeGEM86) were isolated from the nuclear DNA of Olea europaea cv. Carolea and dot-hybridized to the genomic DNA of 14 hypothetically different Olea species, 78 olive cultivars, and 14 wild olives. The copy number per unreplicated haploid genome of OeTaq80- and OeTaq178-related sequences was in the 10(7)-10(6) range and that of OeGEM86-related sequences was in the 10(5) range in cultivars, wild olives and some Olea species. A large variation in the frequency of repeats belonging to each sequence family was observed within each group of plants. Positive correlations existed in each genome between the frequencies of repeats belonging to each family, and their overall frequency was positively correlated to the genome size. Duncan grouping showed that the frequency variation of tandem repeats within each group of plants was not continuous. Two main groups and several subgroups of genotypes could be separated within both the olive cultivars and the wild olives. Discrete areas in the Mediterranean Basin could be delimited by the geographic distribution of cultivated olives with different genotypes and the wild plants were associated with the cultivars in these areas according to genotypic similarity. The Olea species could be divided into four genotypic groups. Three of these, comprising accessions from Asia and North Africa, showed similarity with the genotypes of cultivars and wild olives. These results suggest a polyphyletic origin of cultivated olives from different wild Olea forms distributed throughout the Mediterranean Basin.

Summary. Automated karyotype analyses, nuclear DNA contents, and sequences of rDNA internal transcribed spacers of the nine species in Vicia sect. faba are reported.As karyomorphological parameters are used to evaluate the karyotype evolution, so the determination of the heterochromatin by Feulgen absorption at different thresholds of optical density provided further evidence on the chromatin organization within Vicia sect. faba. The comparison of sequences of rDNA spacers has enabled the definition of the phylogenetic relationships between the analyzed species.

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The nucleotide sequence of the first internal transcribed spacer (ITS1) belonging to different ribosomal RNA genes from Pinus pinea are reported. The analyzed ITS1 can be distinguished on the basis of their length, being one 2631 bp and the other 271 bp long. Nucleotide comparison of these regions did not show appreciable sequence homology. The larger ITS1 contains five tandem arranged subrepeats with size ranging between 219 bp and 237 bp. The nucleotide sequence of the 5.8S and the ITS2 regions belonging to the larger ribosomal RNA gene are also reported.

Tandemly repeated DNA sequences about 60 bp in length, which may be isolated by digestion with FokI restriction endonuclease, were studied by means of molecular and cytological hybridization in Vicia faba and other Vicia species. The results obtained can be summarized as follows: (i) FokI repeats are almost species specific to V. faba, since they hybridize to a minimum extent to genomic DNA of only two out of five related species; (ii) these tandemly repeated elements display variability in structure even within one and the same array, where different repeats may share not more than 71% homology; (iii) their redundancy in the genome of V. faba is remarkably high and varies largely between land races (copy numbers per haploid, 1C, genome range from 21.51 x 10(6) to 5.39 x 10(6)); (iv) FokI repeats are clustered in differing amounts in each subtelocentric pair of the chromosome complement and are missing or present in a nondetectable amount in the submetacentric pair; (vi) chromosome regions that bear these repeats associate closely to varying degrees in interphase nuclei. These results are discussed in relation to possible functional roles that tandemly repeated DNA sequences such as the FokI elements might play.