Strong phylogeographic co-structure between the anther-smut fungus and its white campion host

• Published in: The New phytologist Vol. 212; no. 3; pp. 668 - 679
• Main Authors: Feurtey, Alice, Gladieux, Pierre, Hood, Michael E., Snirc, Alodie, Cornille, Amandine, Rosenthal, Lisa, Giraud, Tatiana
• Format: Journal Article
• Language: English
• Published: England New Phytologist Trust 01.11.2016; Wiley Subscription Services, Inc
• Subjects: Basidiomycota - genetics; Basidiomycota - physiology; coevolution; congruent population structure; cross‐inoculations; Flowers - microbiology; Host-Pathogen Interactions - physiology; local adaptation; Microbotryum violaceum; partial Mantel test; Phylogeography; Plant Diseases - genetics; Plant Diseases - microbiology; Population Dynamics; Silene - genetics; Silene - microbiology; Silene latifolia; MED, Italy; congruent population structure; local adaptation; partial Mantel test; cross-inoculations; coevolution; Microbotryum violaceum
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.14125

Although congruence between host and pathogen phylogenies has been extensively investigated, the congruence between host and pathogen genetic structures at the within-species level has received little attention. Using an unprecedented and comprehensive collection of associated plant–pathogen samples, we investigated the degree of congruence between the genetic structures across Europe of two evolutionary and ecological model organisms, the anther-smut pathogen Microbotryum lychnidis-dioicae and its host plant Silene latifolia. We demonstrated a significant and particularly strong level of host–pathogen co-structure, with three main genetic clusters displaying highly similar spatial ranges in Western Europe, Eastern Europe and Italy, respectively. Correcting for the geographical component of genetic variation, significant correlations were still found between the genetic distances of anthersmut and host populations. Inoculation experiments suggested plant local adaptation, at the cluster level, for resistance to pathogens. These findings indicate that the pathogen remained isolated in the same fragmented southern refugia as its host plant during the last glaciation, and that little long-distance dispersal has occurred since the recolonization of Europe for either the plant or the pathogen, despite their known ability to travel across continents. This, together with the inoculation results, suggests that coevolutionary and competitive processes may be drivers of host–pathogen co-structure.