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The genus Rosa (Rosaceae) is a remarkable genus with respect to systematic biology. Multiple reproductive strategies ranging from apomixis to outcrossing including hybridisation, as well as different modes of character inheritance like matroclinal, paternal or sex unrelated ones. This complexity makes the genus a model in which simple concepts of radiation, speciation and taxonomy come to their limits. Analyses of the evolutionary patterns and processes in Rosa give clear evidence for the stochastic character of this specific evolutionary scenario. [ABSTRACT FROM AUTHOR]

Chemical surface characters play a decisive role in the interaction between plants and their environment. Maternal or paternal inheritance of wax characters in Rosa, section Caninae may allow for ecological niche differentiation according to the parental evolutionary constraints. If so, the radiation of hybrid offspring may reflect the parentally determined framework of interaction and selection against pathogens and abiotic stresses. We tested the inheritance of cuticular chemical wax parameters of reciprocal hybrids within Rosa, section Caninae, the dogroses. We not only found an extremely rich spectrum of chemical compounds on abaxial and adaxial leaf surfaces of dogroses, but also a maternally skewed inheritance of some of these wax characters. The possible role of these findings for the evolution of the allopolyploid dogrose complex is discussed. [ABSTRACT FROM AUTHOR]

Artificial F1 hybrids within dog-roses (Rosa section Caninae (DC.) Ser.) have been assessed for expression of morphological characters with regards to the actual taxonomy applied. In the mostly pentaploid members of the section the unique heterogamous Canina-meiosis leads to matroclinal inheritance of characters by transmitting 4/5 of the genetic information via seed donor whereas 1/5 is provided by the pollen donor. Evaluation of phenotypic variability revealed that the two taxonomically relevant characters “widening of the orifice” and “persistence of the sepals” are statistically significant controlled by the pollen donor. Reciprocal crossings confirmed the same pattern. One possible explanation is that this phenomenon might be subject to genomic imprinting mechanisms. The morphological analysis gives clear evidence that conventional taxonomical concept is artificial and does not reflect the evolutionary patterns among dog-roses. [ABSTRACT FROM AUTHOR]

Classification within the genus Rosa is problematic due to ± continuous variation of morphological characters. The dogroses, ( Rosa, section Caninae) are classified only by their unique meiotic system not by directly visible characters. The intrasectional structure remains insufficient, as the characters (glands, hairs and prickles) are known to exhibit great morphological divergence affected by both genetic plasticity and environmental influences. Taxonomy of dogroses follows a highly artificial system which allows us to identify morphospecies, which are not necessarily evolutionary species. However, SEM-studies in the Caninae revealed that all taxa of the subsection Rubiginosae are characterised by a granule type of epicuticular waxes, whereas members from the other subsections (with three exceptions) form triangular rodlets. Comparison with specimens grown under the same conditions confirmed these findings on natural populations and additionally revealed that following artificial hybridism, offspring develop the maternal type of wax structure due to the matroclinal inheritance in this section. [ABSTRACT FROM AUTHOR]

Information about the topics presented at the 2005 International Botanical Congress (IBC) which was held in Vienna, Austria is presented. The event has featured several research which focus on the evolution of the Rosaceae. A group of researcher has discussed their analysis involving a large data set of molecular sequences, including four chloroplast and six nuclear regions of the said plant species.