RESUMO
Using five SSR markers, polymorphism ofmicrosatellite loci was examined in 46 cultivars and five species of pear (Pyrus ussuriensis, P. bretscgneideri, P. pyraster, and P. elaegnifolia). Most of the accessions examined demonstrated the presence of unique allele sets. The degree of relationship between Russian and Western European pear cultivar was established. It was demonstrated that P. ussuriensis and its first generation progeny were genetically distant from typical cultivars of P. communis, as well as from the P. communis x P. ussuriensis hybrids of later generations. SSR estimates of the cultivar relatedness were shown to correlate with the corresponding pedigree-based estimates. A number of SSR alleles specific to P. ussuriensis were identified. Based on the analysis of microsatellite loci, the allelic composition was determined for each cultivar examined. These data can serve as a molecular certificate of the cultivar.
Assuntos
Repetições de Microssatélites/genética , Pyrus/classificação , Pyrus/genética , Alelos , Análise por Conglomerados , DNA de Plantas/genética , Marcadores Genéticos , Variação Genética , Filogenia , Polimorfismo GenéticoRESUMO
Ty1-copia-like retrotransposons were discovered in all studied plants and form a considerable fraction of their genomes. PCR amplification of a pool of fragments of the reverse transcriptase gene of Ty1-copia-like retrotransposons of the tomato genome was conducted and their physical organization in mitotic and meiotic chromosomes was studied. The method of fluorescence in situ hybridization revealed the location of retrotransposons in the pericentromeric heterochromatin and their absence in the nucleolus organizer region. Knowledge of physical distribution of retrotransposons in the tomato genome is important when constructing molecular markers on their basis. Comparative analysis of chromosomal location of retrotransposons in different plant species extends our knowledge of the plant genome evolution.
Assuntos
Cromossomos de Plantas/genética , Genoma de Planta/genética , Retroelementos/genética , Solanum lycopersicum/genética , Coloração Cromossômica/métodos , Marcadores Genéticos/genética , Heterocromatina/genéticaRESUMO
The nucleotide sequences of the Verticillium wilt resistance locus of resistant and susceptible tomato genotypes were cloned and analyzed. The nucleotide sequences displaying high degree of homology to the earlier cloned Ve1 and Ve2 genes were detected in the tomato forms susceptible to Verticillium wilt. The polymorphism at this locus between the resistant and susceptible plants was detected and used to elaborate a highly efficient CAPS marker.
Assuntos
Genes de Plantas , Doenças das Plantas/microbiologia , Solanum lycopersicum/microbiologia , Verticillium/fisiologia , Sequência de Aminoácidos , Clonagem Molecular , Marcadores Genéticos , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Dados de Sequência Molecular , Doenças das Plantas/genéticaRESUMO
Telomeres, DNA-protein structures, are important elements of the eukaryotic chromosome. Telomeric regions of the majority of higher plants contain heptanucleotides TTTAGGG arranged into a tandem repeat. However, some taxa have no such repeats. These are some species of lilies (Lilium) and onions (Allium). For example, terminal regions of chromosomes of Spanish onion (Allium fistulosum) contain satellite DNA whose unit repeats are 380 bp in length, and the short arm of its chromosome 8 contains rDNA repeats. This study deals with the terminal heterochromatin and organization of the satellite repeat in A. fistulosum. Fluorescent in situ hybridization (FISH) was used to locate the satellite DNA on chromosomes and on extended DNA of A. fistulosum. Nonsatellite DNA was found in the structure of telomeric repeat. Polymerase chain reaction (PCR) and Southern hybridization were used for analysis of terminal heterochromatin. Various rearrangements were found in the satellite repeat. The roles of retrotransposones and microsatellites in the formation of terminal heterochromatin are discussed.
