Canonical correlations reveal adaptive loci and phenotypic responses to climate in perennial ryegrass

Germplasm from perennial ryegrass (Lolium perenne L.) natural populations is useful for breeding because of its adaptation to a wide range of climates. Climate‐adaptive genes can be detected from associations between genotype, phenotype and climate but an integrated framework for the analysis of these three sources of information is lacking. We used two approaches to identify adaptive loci in perennial ryegrass and their effect on phenotypic traits. First, we combined Genome‐Environment Association (GEA) and GWAS analyses. Then, we implemented a new test based on a Canonical Correlation Analysis (CANCOR) to detect adaptive loci. Furthermore, we improved the previous perennial ryegrass gene set by de novo gene prediction and functional annotation of 39,967 genes. GEA‐GWAS revealed eight outlier loci associated with both environmental variables and phenotypic traits. CANCOR retrieved 633 outlier loci associated with two climatic gradients, characterized by cold‐dry winter versus mild‐wet winter and long rainy season versus long summer, and pointed out traits putatively conferring adaptation at the extremes of these gradients. Our CANCOR test also revealed the presence of both polygenic and oligogenic climatic adaptations. Our gene annotation revealed that 374 of the CANCOR outlier loci were positioned within or close to a gene. Co‐association networks of outlier loci revealed a potential utility of CANCOR for investigating the interaction of genes involved in polygenic adaptations. The CANCOR test provides an integrated framework to analyse adaptive genomic diversity and phenotypic responses to environmental selection pressures that could be used to facilitate the adaptation of plant species to climate change

Biological flora of the British isles: Ulmus glabra

1. This account presents information on all aspects of the biology of Ulmus glabra Hudson (wych elm) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. 2. Ulmus glabra is a large forest tree, and often an important canopy tree in ancient and seminatural woodlands. It is primarily native to the north and west of Britainand much of mainland Europe. It is the only elm native to Ireland. It is the most distinct of the British elms in that it rarely suckers and sets abundant viable seed. Although found on limestone screes and cliffs, and hedgerows, it is primarily awoodland tree, especially on moist, basic soils. In many secondary woodlands, it often cooccurs with Acer pseudoplatanus and has ecological needs that are similar to Fraxinus excelsior. 3. Ulmus glabra has clusters of c. 25 hermaphrodite flowers appearing before the leaves on previous year’s growth. Seeds are wind dispersed, falling in April to July, but remain viable for only a few days. Nevertheless, seedling establishment can be abundant. Hybridisation with other northern European elms is common but hybrids are notoriously difficult to identify and therefore probably under recorded. 4. The health and survival of wych elm in Europe has been seriously compromised since the 1970s due to Dutch elm disease caused by the fungus Ophiostoma novo ulmi, transmitted by elm bark beetles (Scolytus spp.). To the south of its Scottish stronghold, many elms are reduced to small trees regrowing from basal sprouts or seeds. These trees tend to be reinfected once trunk diameter exceeds 10 cm. Fortunately for its long term survival, seed production usually begins a number of years before they are reinfected