Data from: Colonization history, host distribution, anthropogenic influence and landscape features shape populations of white pine blister rust, an invasive alien tree pathogen

White pine blister rust is caused by the fungal pathogen Cronartium ribicola J.C. Fisch (Basidiomycota, Pucciniales). This invasive alien pathogen was introduced into North America at the beginning of the 20th century on pine seedlings imported from Europe and has caused serious economic and ecological impacts. In this study, we applied a population and landscape genetics approach to understand the patterns of introduction and colonization as well as population structure and migration of C. ribicola. We characterized 1,292 samples of C. ribicola from 66 geographic locations in North America using single nucleotide polymorphisms (SNPs) and evaluated the effect of landscape features, host distribution, and colonization history on the structure of these pathogen populations. We identified eastern and western genetic populations in North America that are strongly differentiated. Genetic diversity is two to five times higher in eastern populations than in western ones, which can be explained by the repeated accidental introductions of the pathogen into northeastern North America compared with a single documented introduction into western North America. These distinct genetic populations are maintained by a barrier to gene flow that corresponds to a region where host connectivity is interrupted. Furthermore, additional cryptic spatial differentiation was identified in western populations. This differentiation corresponds to landscape features, such as mountain ranges, and also to host connectivity. We also detected genetic differentiation between the pathogen populations in natural stands and plantations, an indication that anthropogenic movement of this pathogen still takes place. These results highlight the importance of monitoring this invasive alien tree pathogen to prevent admixture of eastern and western populations where different pathogen races occur

Data from: Colonization history, host distribution, anthropogenic influence and landscape features shape populations of white pine blister rust, an invasive alien tree pathogen

White pine blister rust is caused by the fungal pathogen Cronartium ribicola J.C. Fisch (Basidiomycota, Pucciniales). This invasive alien pathogen was introduced into North America at the beginning of the 20th century on pine seedlings imported from Europe and has caused serious economic and ecological impacts. In this study, we applied a population and landscape genetics approach to understand the patterns of introduction and colonization as well as population structure and migration of C. ribicola. We characterized 1,292 samples of C. ribicola from 66 geographic locations in North America using single nucleotide polymorphisms (SNPs) and evaluated the effect of landscape features, host distribution, and colonization history on the structure of these pathogen populations. We identified eastern and western genetic populations in North America that are strongly differentiated. Genetic diversity is two to five times higher in eastern populations than in western ones, which can be explained by the repeated accidental introductions of the pathogen into northeastern North America compared with a single documented introduction into western North America. These distinct genetic populations are maintained by a barrier to gene flow that corresponds to a region where host connectivity is interrupted. Furthermore, additional cryptic spatial differentiation was identified in western populations. This differentiation corresponds to landscape features, such as mountain ranges, and also to host connectivity. We also detected genetic differentiation between the pathogen populations in natural stands and plantations, an indication that anthropogenic movement of this pathogen still takes place. These results highlight the importance of monitoring this invasive alien tree pathogen to prevent admixture of eastern and western populations where different pathogen races occur

Neighbor-joining tree based on Nei’s unbiased pairwise genetic distances derived from the allele frequency at 31 SNPs among 66 North American populations of <i>Cronartium ribicola</i>.

<p>East, Midwest, Northwest and US West refer to regions in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127916#pone.0127916.s005" target="_blank">S1 Table</a>.</p

Analysis of molecular variance for <i>Cronartium ribicola</i> populations sampled across geographic regions, hosts and landscapes in North America.

<p>^aComparison among and within groups of populations arranged by geographic origin, type of stand, pine host and elevation.</p><p>^bProbability that the observed value is larger than the value calculated following permutation (**p<0.01). Φ_c<b>t</b> values were tested by permuting whole populations among groups.</p><p>^cSee <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127916#pone.0127916.s005" target="_blank">S1 Table</a> for details. Three pine species in western populations were considered: <i>P</i>. <i>monticola</i>, <i>P</i>. <i>albicaulis</i>, and <i>P</i>. <i>flexilis</i><b>.</b> Other pine species (<i>P</i>. <i>strobus</i>, <i>P</i>. <i>strobiformis</i>) would have generated confounded effect of host and geography.</p><p>Analysis of molecular variance for <i>Cronartium ribicola</i> populations sampled across geographic regions, hosts and landscapes in North America.</p

Principal component analysis using a pairwise population matrix of mean population codominant genotypic genetic distances among 66 North American populations of <i>Cronartium ribicola</i>.

<p>First and second components, accounting for 70% and 9% of the total genetic variability. B) First and third components, accounting for 70% and 7% of the total variability. East, Midwest, Northwest and US West refer to regions in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127916#pone.0127916.s005" target="_blank">S1 Table</a>.</p