The diploid origins of allopolyploid rose species studied using single nucleotide polymorphism haplotypes flanking a microsatellite repeat

The taxonomy of the genus Rosa is complex, not least because of hybridisations between species. We aimed to develop a method to connect the diploid Rosa taxa to the allopolyploid taxa to which they contributed, based on the sharing of haplotypes. For this we used an SNPSTR marker, which combines a short tandem repeat (STR; microsatellite) marker with single nucleotide polymorphisms (SNPs) in the flanking sequences. In total, 53 different sequences (haplotypes) were obtained for the SNPSTR marker, Rc06, from 20 diploid and 35 polyploid accessions from various species of Rosa. Most accessions of the diploid species had only one allele, while accessions of the polyploid species each contained two-to-five different alleles. Twelve SNPs were detected in the flanking sequences, which alone formed a total of 18 different haplotypes. A maximum likelihood dendrogram revealed five groups of haplotypes. Diploid species in the same Section of the genus Rosa contained SNP haplotypes from only one haplotype group. In contrast, polyploid species contained haplotypes from different haplotype groups. Identical SNP haplotypes were shared between polyploid species and diploid species from more than one Section of the genus Rosa. There were three different polymorphic repeat regions in the STR region. The STR repeat contained eight additional SNPs, but these contributed little to the resolution of the haplotype groups. Our results support hypotheses on diploid Rosa species that contributed to polyploid taxa. Finding different sets of haplotypes in different groups of species within the Sections Synstylae and Pimpinellifoliae supports the hypothesis that these may be paraphyletic

Functional trait values, not trait plasticity, drive the invasiveness of Rosa sp in response to light availability

PREMISE OF THE STUDY : Functional trait plasticity in resource capture traits has been suggested as an underlying mechanism promoting invasive species establishment and spread. Earlier studies on this mechanism treat invasiveness as a discrete characteristic (i.e., invasive vs. noninvasive) and do not consider the potential impacts of evolutionary history. In the present study, we used a continuous measure of invasiveness and a phylogenetic framework to quantify the relationship between functional trait expression, plasticity, and invasiveness in Rosa. METHODS : In a manipulative greenhouse experiment, we evaluated how light availability affects functional traits and their plasticity in Rosa sp. and the out-group species, Potentilla recta, which vary in their invasiveness. KEY RESULTS : Across functional traits, we found no significant relationship between plasticity and invasiveness. However, more invasive roses demonstrated an ability to produce a more branched plant architecture, promoting optimal light capture. Invasiveness also was linked with lower photosynthetic and stomatal conductance rates, leading to increased water-use efficiency (WUE) in more invasive roses. CONCLUSIONS : Our results suggest that functional trait values, rather than plasticity, promote invasive rose success, counter to earlier predictions about the role of plasticity in invasiveness. Furthermore, our study indicates that invasive roses demonstrate key functional traits, such as increased WUE, to promote their success in the high-light, edge habitats they commonly invade