Juliane Ramser

Genetic variation and cultivar identification of Jamaican yam germplasm by random amplified polymorphic DNA analysis

SummaryWe have used random amplified polymorphic DNA (RAPD) analysis to characterize eleven cultivars of the five economically most important yam species grown in Jamaica (Dioscorea alata, D. cayenensis, D. rotundata, D. trifida and D. esculenta). Amplification of genomic DNA samples with nine different arbitrary 10mer primers revealed a total of 338 different band positions, ranging in size from 0.3 to 2.5 kb. RAPD patterns proved to be highly reproducible and somatically stable. While no variation was observed among plants belonging to the same cultivar, a large number of intervarietal and interspecific polymorphisms enabled us to reliably discriminate between all Jamaican cultivars investigated.

Oligonucleotide Fingerprinting in Plants and Fungi

Synthetic oligonucleotides complementary to simple repetitive DNA sequence motifs are now routinely applied for multilocus DNA fingerprinting of humans and a large variety of animal species. Most recently, these probes have also been used successfully for the analysis of plant and fungal genomes. All simple motifs investigated to date (CA-, CT-, GATA-, GACA-, GAA-, GTG - GGAT- and TCC-multimers) are present and repeated to various extents throughout the plant and fungal kingdoms. Usually, these probes reveal intra- and interspecific genetic variability resulting in polymorphic or even hypervariable banding patterns. Depending on the combination of species and oligonucleotide probe, species- variety-, accession-, strain-or individual-specific “fingerprints” were obtained in plants and fungi. Somatic stability was observed. For their successful application to DNA fingerprinting, the optimal probe/species-combinations that give distinct banding patterns have to be developed empirically. Various applications of plant DNA fingerprinting using oligonucleotide probes are suggested: (1) characterization of the extent of genetic variability within races, (2) assessment of the “purity” of inbred lines, (3) selection of the recurrent parental genome in backcross breeding programs, (4) identification of crop cultivars and fungal strains, (5) characterization of fusion hybrids, (6) evaluation of the extent of somaclonal variation at the molecular level.

Multilocus DNA fingerprinting and genetic relatedness in plants: A case study with banana and tomato

The technique of DNA fingerprinting is frequently used for studies of genetic diversity and relatedness in a wide range of organisms. In humans and animals, multilocus fingerprints are mainly applied to paternity and identity test cases, behavioral ecology, and the analysis of population structures. In plants and fungi, the frequent occurrence of low-variability fingerprint patterns additionally allows to use multilocus fingerprinting for studying taxonomical problems at an intraspecific level. In the present article, we (1) present an overview of such approaches in a series of plant species, (2) summarize our attempts to estimate genetic relationships within two cultivated plant species, banana and tomato, by band sharing data derived from oligonucleotide fingerprints, and (3) discuss the limitations and potentials of multilocus fingerprinting for the determination of genetic relatedness.