Data Descriptor: Ash leaf metabolomes reveal differences between trees tolerant and susceptible to ash dieback disease

CMS was funded by the ‘Nornex’ project jointly by UK BBSRC (BBS/E/J/000CA5323) and DEFRA and a BBSRC Tools and Resources grant (BB/N021452/1) awarded to M.G. and D.J.S

Transglutaminase activation in neurodegenerative diseases

The following review examines the role of calcium in promoting the in vitro and in vivo activation of transglutaminases in neurodegenerative disorders. Diseases such as Alzheimer's disease, Parkinson's disease and Huntington's disease exhibit increased transglutaminase activity and rises in intracellular calcium concentrations, which may be related. The aberrant activation of transglutaminase by calcium is thought to give rise to a variety of pathological moieties in these diseases, and the inhibition has been shown to have therapeutic benefit in animal and cellular models of neurodegeneration. Given the potential clinical relevance of transglutaminase inhibitors, we have also reviewed the recent development of such compounds

Genetic variation of Fraxinus excelsior half-sib families in response to ash dieback disease following simulated spring frost and summer drought treatments

Ten juvenile Fraxinus excelsior half-sib families from two Lithuanian populations have been tested in the controlled environment for their response to ash dieback disease caused by Hymenoscyphus fraxineus, detecting changes of genetic variation and heritability, as well as estimating genotype by environment (G×E) interaction and phenotypic plasticity following artificial spring frost and summer drought treatments. In 2014, a batch of 200 four-year-old ash seedlings was used for each treatment and control (no treatment). Health condition, bud flushing phenology and height were assessed for each seedling, and disease incidence and survival ratios were assessed for each family both before (at the beginning of the vegetation season) and after the treatments (at the end of the vegetation season). Disease incidence ratio increased from 0.77-0.80 up to 0.90-0.95. Tree mortality rates during one vegetation season were significantly lower in the frost treatment (21%) than in the drought treatment (25%) or control (31%). None of the tested F. excelsior families were completely resistant to ash dieback, although significant among-family differences in disease incidence and damage rates suggest an additive mode of gene action and thus a quantitative resistance to the disease. Neither disease incidence rates, nor tree health condition scores differed significantly among the applied treatments (including control) indicating in general a negligible effect of the simulated adverse conditions on health status of the ash seedlings. However, G×E interaction was found to be significant (at P > 0.05) for disease incidence, length of necrotic shoots and tree survival, implying that susceptibility of ash families to the dieback disease unequally depends on environmental conditions, and indicating a presence of genetic variation in plasticity and reaction norms of the tested families across environments (treatments). Substantially increased coefficients of additive genetic variation and heritability in health condition following both frost and drought treatments and compared to control showed that simulated stress conditions may noticeably contribute to expression of differences among the tested F. excelsior families in their resistance traits, thus enabling a better evaluation of performance of different families, an effective family selection for resistance, and achievement of a marked genetic gain

The viability of a breeding programme for ash in the British Isles in the face of ash dieback

To evaluate the viability and feasibility of a future breeding programme to produce trees resistant to an emerging pest or pathogen, it is helpful to ask the following questions: How much variation in resistance exists in tree populations? To what extent is this resistance heritable? How many genetic loci are involved? What level of resistance is found in other species of the same genus? Here, we survey current knowledge of these issues in relation to the degree of resistance of European ash (Fraxinus excelsior) to H. fraxineus, the fungus causing ash dieback (ADB). Several studies have found a low frequency of heritable resistance in F. excelsior populations, which seems to be determined by many genetic loci. This suggests that a breeding programme is viable and that natural selection may also increase the mean resistance of populations over time. More research is needed on the genetic basis of resistance to ADB to understand how quickly natural selection can operate in woodlands and what acceleration may be possible in breeding programmes, including via use of genetic markers. Hybrid breeding programmes may also be a possibility, as some ash species appear to be more resistant to ADB than is F. excelsior, but more research is needed on this issue. We do not yet know if it will be possible to breed F. excelsior to have resistance to both ADB and the emerging threat of emerald ash borer. We recommend short‐term mitigation measures for the ADB epidemic and future research directions

Common Ash (Fraxinus excelsior L.)

Common ash (Fraxinus excelsior L.) has an extensive natural distribution across Europe and extends as far east as the Volga river and south into northern Iran. Country statistics and national programmes show that common ash has major economic and ecological importance in many countries. Genetic improvement has concentrated on tree quality and adaptive traits and more recently on developing resistance to the pathogen Chalara fraxinea which is a severe threat to this species. Data is presented from provenance / progeny trials in Lithuania, France, Belgium, The Netherlands and Romania on genetic variation for adaptive traits, growth and tree quality. There is large variation among and within ash genetic sources for important characters. Estimates for genetic heritability were high for height growth, and stem form and strong site effects were noted for these traits and for stem diameter. The breeding system with regard to genetic diversity, gene flow, hybridisation and inbreeding is reviewed. For breeding, various methodologies regarding mating, testing and selection are discussed. A review on vegetative propagation, including in vitro culture and cryopreservation is presented as useful tools in breeding programme

Variation in mechanical properties of selected young poplar hybrid crosses

To better understand the variability in mechanical properties caused by genetic differences in hybrid poplars, modulus of elasticity and modulus of rupture in static bending were examined at two 10-year-old clonal trials located at Windsor and St-Ours, southern Quebec, Canada. The materials consisted of three hybrids, Populus deltoides x Populus nigra, Populus trichocarpa x P. deltoides, Populus maximowiczii x Populus balsamifera, and native P. deltoides. Significant differences were observed in mechanical properties among hybrids and P. deltoides. The effects of growth on the mechanical properties were inconsistent and varied considerably by site and by hybrid. Results indicated no uniform trends relating growth rate to either higher or lower modulus of elasticity/modulus of rupture. It appears that selection for strength properties may not uniformly lead to decreased growth production, especially for P. trichocarpa x P. deltoides and P. maximowiczii x P. balsamifera. Copyright © 2008 by the Society of American Foresters

Response of juvenile progeny of seven forest tree species and their populations to simulated climate change-related stressors, heat, elevated humidity and drought

The study aimed to evaluate response and phenotypic plasticity of juvenile progeny of seven forest tree species Pinus sylvestris, Picea abies, Quercus robur, Fraxinus excelsior, Alnus glutinosa, Betula pendula and Populus tremula and their populations to climate change-related stressors, simulated in a phytotron - heat and elevated humidity and heat and drought - in comparison to performance in ambient (control) conditions. Treatment effect on sapling morphometric, physiological and biochemical traits was significant except for health condition, transpiration and photosynthetic rates and water use efficiency (WUE). Species effect and species-by-treatment interaction were strongly significant in most traits studied, indicating a great inter-specific variability of responses to the applied treatments. Compared to control, stem diameter increment was lower for most species following both hot-wet and hot-dry treatments, while treatment impact on height increment was less pronounced and sometimes even positive. Drought caused significant defoliation in P. tremula, A. glutinosa and B. pendula, while under hot-wet treatment the defoliation in most species was lower than in control. Following hot dry treatment, WUE in P. abies, P. sylvestris and B. pendula was lower than following both hot-wet treatment and control, while in P. tremula, A. glutinosa and Q. robur WUE was higher. This suggests that the latter species are able to maintain a balance between photosynthesis and transpiration. Photosynthetic rate was highest in P. tremula, B. pendula and A. glutinosa, however it was much more negatively affected by water deficit in these three species than in other tested species. In most cases, drought had a negative effect on production of pigments in deciduous tree species, which, together with increased amounts of malondialdehyde and hydrogen peroxide, indicated a presence of an oxidative stress. Significant population effect and population-by-treatment interactions found for most traits showed different plasticity and response of tree populations to the treatments. Although, only 19% of the populations showed significant ecovalencies. Some of the observed reactions may not be considered as adaptive acclimation as decreasing growth of some species and populations indicates deteriorating performance which may lead to changes in their competitiveness, thus compromising regeneration, persistence of natural successions and sustainability of forest ecosystems