Rosa canina research paper

Title: Evolutionary implications of permanent odd polyploidy in the stable sexual, pentaploid of Rosa canina L.

Authors: Lim KY, Werlemark G, Matyasek R, Bringloe JB, Sieber V, El Mokadem H, Meynet J, Hemming J, Leitch AR, Roberts AV.

Authors affiliation: School of Biological Sciences, Queen Mary, University of London, London E1 4NS, UK.

Published in: Heredity. 2005 May; volumn 94(5): pages 501-6.

Abstract: In Rosa canina (2n = 5x = 35), the pollen and ovular parents contribute, respectively, seven and 28 chromosomes to the zygote. At meiosis I, 14 chromosomes form seven bivalents and 21 chromosomes remain as univalents. Fluorescent in situ hybridization to mitotic and pollen mother cells (PMC) of R. canina showed that 10 chromosomes (two per genome) carry ribosomal DNA (rDNA) loci. Five chromosomes carry terminal 18S-5.8S-26S rDNA loci; three of these also carry paracentric 5S rDNA loci and were designated as marker chromosomes 1. Five chromosomes carry only 5S rDNA loci and three of these were designated as marker chromosomes 2. The remaining four of the 10 chromosomes with rDNA loci were individually identifiable by the type and relative sizes of their rDNA loci and were numbered separately. At PMC meiosis, two marker chromosomes 1 and two marker chromosomes 2 formed bivalents, whereas the others were unpaired. In a gynogenetic haploid of R. canina (n = 4x = 28), obtained after pollination with gamma-irradiated pollen, chromosomes at meiosis I in PMC remained predominantly unpaired. The data indicate only one pair of truly homologous genomes in R. canina. The 21 unpaired chromosomes probably remain as univalents through multiple generations and do not recombine. The long-term evolutionary consequence for the univalents is likely to be genetic degradation through accumulated mutational change as in the mammalian Y chromosome and chromosomes of asexual species. But there is no indication that univalents carry degenerate 5S rDNA families. This may point to a recent evolution of the R. canina meiotic system."

Title: Evolution by reticulation: European dogroses originated by multiple hybridization across the genus rosa.

Authors: Ritz CM, Schmuths H, Wissemann V.

Authors affiliation: Institute of Systematic Botany, University of Jena, Philosophenweg 16, D-07743 Jena, Germany.

Published in: J Hered. 2005 Jan-Feb; volumn 96(1):pages 4-14.

Abstract: “The European dogroses (Rosa sect. Caninae (DC.) Ser.) are characterized by a unique meiosis system (“canina-meiosis”), which controls the heterogamous development of tetraploid egg cells and haploid pollen grains resulting in a pentaploid somatic status. This permanent anorthoploidy is supposed to have originated by a hybridization event in the postglacial period. In this study we present molecular evidence by an analysis of nuclear ribosomal DNA data that dogroses are complex allopolyploids resulting from multiple hybridization events. As previously described, the nrITS-1 region does not undergo concerted evolution in dogroses. Thus, different ITS-1 sequences persist within single individuals. Secondary structure predictions do not point to the existence of pseudogenes within these ITS-1 types. Our data suggest that the pentaploid Caninae genome originated from different members of nondogroses and the now extinct Protocaninae.”

Hi all,

What little I understood was interesting but I must admit that it was a little technical in parts. Could anyone put it in laymen

Interesting papers Henry! I