Plant Health Protocols for the Reintroduction of Native Plants

Many botanic gardens and conservation agencies are now cultivating threatened native species specifically for reintroduction programmes in response to the second part of Target 8 of the Global Strategy for Plant Conservation (GSPC). While collection, cultivation and reintroduction techniques are frequently discussed in workshops and described in papers, few seem to have considered the threats of introducing non-native pests, diseases, weeds and hybrids between different populations of the same species. The Royal Botanic Garden Edinburgh has been cultivating plants for its Target 8 programme since 2005 and now grows 82 per cent threatened Scottish species. It is running active reintroduction programmes for nine of these species with programmes planned for a further five species. In recent years increasing attention has been paid to reducing the risks of introducing non-native organisms and hybrids between different populations of native species into the wild.This paper describes the protocols that have been developed, including verification, screening for pests and diseases, averting spontaneous hybridisation and preparing plants for reintroduction

A Genome-Wide Association study in Arabidopsis thaliana to decipher the adaptive genetics of quantitative disease resistance in a native heterogeneous environment

Pathogens are often the main selective agents acting in plant communities, thereby influencing the distribution of polymorphism at loci affecting resistance within and among natural plant populations. In addition, the outcome of plant-pathogen interactions can be drastically affected by abiotic and biotic factors at different spatial and temporal grains. The characterization of the adaptive genetic architecture of disease resistance in native heterogeneous environments is however still missing. In this study, we conducted an in situ Genome-Wide Association study in the spatially heterogeneous native habitat of a highly genetically polymorphic local mapping population of Arabidopsis thaliana, to unravel the adaptive genetic architecture of quantitative disease resistance. Disease resistance largely differed among three native soils and was affected by the presence of the grass Poa annua. The observation of strong crossing reactions norms among the 195 A. thaliana genotypes for disease resistance among micro-habitats, combined with a negative fecundity-disease resistance relationship in each micro-habitat, suggest that alternative local genotypes of A. thaliana are favored under contrasting environmental conditions at the scale of few meters. A complex genetic architecture was detected for disease resistance and fecundity. However, only few QTLs were common between these two traits. Heterogeneous selection in this local population should therefore promote the maintenance of polymorphism at only few candidate resistance genes

Starting a conservation collection of Sorbus pseudomeinichii

There are three endemic Sorbus species on the Isle of Arran in Scotland: Sorbus arranensis, S. pseudofennica and S. pseudomeinichii. The latter is the most recently discovered and is represented in the wild by a single individual. Seed propagation and vegetative propagation by chip budding were initiated for all three species at the Royal Botanic Garden Edinburgh (RBGE). This has been successful and there are now conservation collections of these species growing at RBGE

The Genetic Architecture of Adaptation to Leaf and Root Bacterial Microbiota in Arabidopsis thaliana

Understanding the role of the host genome in modulating microbiota variation is a need to shed light on the holobiont theory and overcome the current limits on the description of host-microbiota interactions at the genomic and molecular levels. However, the host genetic architecture structuring microbiota is only partly described in plants. In addition, most association genetic studies on microbiota are often carried out outside the native habitats where the host evolves and the identification of signatures of local adaptation on the candidate genes has been overlooked. To fill these gaps and dissect the genetic architecture driving adaptive plant-microbiota interactions, we adopted a genome-environment association (GEA) analysis on 141 whole-genome sequenced natural populations of Arabidopsis thaliana characterized in situ for their leaf and root bacterial communities in fall and spring, and a large range of nonmicrobial ecological factors (i.e., climate, soil, and plant communities). A much higher fraction of among-population microbiota variance was explained by the host genetics than by nonmicrobial ecological factors. Importantly, the relative importance of host genetics and nonmicrobial ecological factors in explaining the presence of particular operational taxonomic units (OTUs) differs between bacterial families and genera. In addition, the polygenic architecture of adaptation to bacterial communities was highly flexible between plant compartments and seasons. Relatedly, signatures of local adaptation were stronger on quantitative trait loci (QTLs) of the root microbiota in spring. Finally, plant immunity appears as a major source of adaptive genetic variation structuring bacterial assemblages in A. thaliana

Data Capture Project at the Royal Botanic Garden Edinburgh

Botanic gardens, with their large holdings of living plants collected from around the world, are important guardians of plant biodiversity, but acquiring and curating these genetic resources is enormously expensive. For these reasons it is crucial that botanic gardens document and curate their collections in order to gain the greatest benefit from the plants in their care. Great priority is given to making detailed field notes and the process of documentation is often continued during the plants formative years when being propagated. However, for the large majority of plants this process often stops once the material is planted in its final garden location. The Data Capture Project at the Royal Botanic Garden Edinburgh is an attempt to document specific aspects of the plant collections so that the information captured can be of use to the research community even after the plants have died

Divergence-free cut finite element methods for Stokes flow

We develop two unfitted finite element methods for the Stokes equations based on $\mathbf{H}^{\text{div}}$-conforming finite elements. The first method is a cut finite element discretization of the Stokes equations based on the Brezzi-Douglas-Marini elements and involves interior penalty terms to enforce tangential continuity of the velocity at interior edges in the mesh. The second method is a cut finite element discretization of a three-field formulation of the Stokes problem involving the vorticity, velocity, and pressure and uses the Raviart-Thomas space for the velocity. We present mixed ghost penalty stabilization terms for both methods so that the resulting discrete problems are stable and the divergence-free property of the $\mathbf{H}^{\text{div}}$-conforming elements is preserved also for unfitted meshes. We compare the two methods numerically. Both methods exhibit robust discrete problems, optimal convergence order for the velocity, and pointwise divergence-free velocity fields, independently of the position of the boundary relative to the computational mesh

Do native and invasive herbivores have an effect on Brassica rapa pollination?

Mutualistic (e.g. pollination) and antagonistic (e.g. herbivory) plant–insect interactions shape levels of plant fitness and can have interactive effects. By using experimental plots of Brassica rapa plants infested with generalist (Mamestra brassicae) and specialised (Pieris brassicae) native herbivores and with a generalist invasive (Spodoptera littoralis) herbivore, we estimated both pollen movement among treatments and the visiting behaviour of honeybees versus other wild pollinators. Overall, we found that herbivory has weak effects on plant pollen export, either in terms of inter‐treatment movements or of dispersion distance. Plants infested with the native specialised herbivore tend to export less pollen to other plants with the same treatment. Other wild pollinators preferentially visit non‐infested plants that differ from those of honeybees, which showed no preferences. Honeybees and other wild pollinators also showed different behaviours on plants infested with different herbivores, with the former tending to avoid revisiting the same treatment and the latter showing no avoidance behaviour. When taking into account the whole pollinator community, i.e. the interactive effects of honeybees and other wild pollinators, we found an increased avoidance of plants infested by the native specialised herbivore and a decreased avoidance of plants infested by the invasive herbivore. Taken together, our results suggest that herbivory may have an effect on B. rapa pollination, but this effect depends on the relative abundance of honeybees and other wild pollinators

Plant Collecting for the Ecological Garden and the Scottish Heath Garden at the Royal Botanic Garden Edinburgh

The Ecological and Heath Gardens at the Royal Botanic Garden Edinburgh were created in 1991 and 1997 respectively. The Ecological Garden started as a naturalistic area of native woodland plants where cryptogams were encouraged to grow. Building on its success other habitat types were created nearby. The Heath Garden replaced an older heather garden and sought to recreate the ‘feel’ of a Scottish upland heathland. In recent years additional wild origin material of conservation concern has been added to each Garden and this paper describes the process along with some of the plants selected