Genetic variability and reproductive strategies in Nordic dogroses, Rosa section Caninae

In the present thesis, I investigate the morphological variation among and within Nordic dogrose species (Rosa section Carzirzae), and the transmittal of morphological characters and molecular markers to interspecific progeny plants. The occurrence of apomixis within the section is also investigated. All species within section Caninae are polyploid and characterised by their unique meiosis with unequal distribution of maternal and paternal chromosomes to their progeny. The pollen parent contributes only seven chromosomes, whereas the seed parent contributes 21, 28 or 35 chromosomes depending on ploidy level. The dogrose species are morphologically rather distinct. Both reproductive and vegetative morphological characters could differentiate among the investigated taxa, with the exception of the two subspecies of R. dumalis, subsp. corifoliia and subsp. dumalis. Rosa rubiginosa appeared to be the most homogeneous of the species, both within and among populations, and R. dumalis the most heterogeneous, both within and among populations. Rosa villosa was heterogeneous among populations but showed high within-population homogeneity. Morphological characters could also separate interspecific hybrids from progeny groups representing the parental species and the influence from the seed parent was apparent as expected from the skewed distribution of chromosomes. The matroclinal inheritance of molecular markers is also very pronounced, since all but two maternal markers were transmitted to all the interspecific progeny plants. In contrast, only approximately half of the paternal markers were transmitted to the progenies. The degree of homology between the constituent genomes in the parents decide to what extent the genetic contribution of the pollen parent will be recognizable in the progeny plant, both in morphological characters and in molecular markers. The genomes could be separated by size polymorphism in their respective NOR sites. Apparently two of the five consituent genomes in one pentaploid plant were never involved in the bivalent formation. Apomixis appears to occur to a limited extent within the dogroses, indicated by elevated pollen via- bility compared to the experimentally derived hybrid plants, and a complete lack of paternal parent-specific molecular marke

Author

• Gun Werlemark

• rosa
• genetic variation
• apomixis
• hybridization
• scandinavia
• Rosa sect. Caninae
• Rosaceae
• genetic diversity
• matroclinal inheritance
• RAPD
• microsatellites
• in situ hybridization

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https://pub.epsilon.slu.se/44/

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oai:pub.epsilon.slu.se:44