Satellite DNA specific to the oat C genome was sequenced and located on chromosomes of diploid, tetraploid, and hexaploid Avena ssp. using in situ hybridization. The sequence was present on all seven C genome chromosome pairs and hybridized to the entire length of each chromosome, with the exception of the terminal segments of some chromosome pairs. Three chromosome pairs belonging to the A genome showed hybridization signals near the telomeres of their long arms. The existence of intergenomic chromosome rearrangements and the deletions of the repeated units are deduced from these observations. The number of rDNA loci (18S–5.8S–26S rDNA) was determined for the tetraploid and hexaploid oat species. Simultaneous in situ hybridization with the satellite and rDNA probes was used to assign the SAT chromosomes of these species to their correct genomes.Key words: oats, satellite DNA, rDNA, in situ hybridization, genome evolution.

In combination with oligonucleotides of arbitrary sequence, 5′ anchored oligonucleotides based on simple sequence repeats were used in polymerase chain reaction amplifications to produce barley DNA fingerprints. The aim of this work was (i) to develop a simple nonradioactive experimental procedure to reveal polymorphism in regions containing SSRs, (ii) to determine the genetic nature of polymorphisms, and (iii) to investigate the efficacy of polymorphisms contained in such fingerprints in disclosing genetic relationships between 14 European barley cultivars with known pedigrees. Different 10-mer oligonucleotides containing a dinucleotide motif were used as single primers and also in pairs with 10-mer oligonucleotides of arbitrary sequence. Further, the arbitrary oligonucleotides were used as single primers to produce RAPDs. Thirteen combinations of primers containing either GT(CA)₄or GC(CA)₄were selected on the basis of number and intensity of scorable bands in silver-stained 7% polyacrylamide gels. Of the fragments scored, 58.4% were polymorphic. Inheritance of these random amplified microsatellite polymorphic fragments (RAMP) was studied in doubled-haploid lines from the F₁of 'Steptoe' × 'Morex'. Fifty percent of the primers generated codominant markers. Genetic similarities between cultivars were estimated from RAMP and RAPD data. Principal coordinate analysis performed on RAMP data revealed a clear separation of winter six-rowed, winter two-rowed, and spring two-rowed barley. The dendograms generated faithfully reflected the genealogies of the barley cultivars. RAPD failed to show clearly the germplasm sources of the experimental cultivars. Key words : simple sequence repeats, microsatellites, amplification, genetic diversity, barley.

Two molecular marker technologies, random amplified microsatellite polymorphism (RAMP) and simple sequence repeats (SSR), were used to determine genetic diversity of 27 accessions of the wild barley Hordeurn culgure ssp. spontuneum. 19 primer combinations were used to generate RAMP fragments and 16 SSR loci were analysed. A high level of polymorphism was found with both kind of markers as revealed by the mean polymorphism information content (PIC) values obtained: 0.838 and 0.855 for RAMP and SSR, respectively. Genetic dissimilarities between genotypes were estimated from RAMP and SSR data. A lack of correlation was found between both sets of data. This was reflected in the two dendrograms obtained which presented accessions clustered differently. The results suggest that both sets of markers reveal genetic variation induced by different mechanisms. The dendrogram produced from the RAMP dissimilarity estimates showed most of the groups related to the geographic origin of the accessions.