Leaf spots caused by Septoria populicola. Photo credit: Nicole Lecours

Septoria populicola (sexual stage: M. populicola) is a forest fungal pathogen that most commonly affects poplars of the section Tacamahaca and theirs hybrids. Balsam poplar (Populus balsamifera) and black cottonwood (P. trichocarpa) are native hosts in North America. The symptoms are leaf spots, developing late spring or early summer that can lead to severe defoliation under environmental inductive conditions. S. populicola has been reported to causes cankers on P. balsamifera in exceptional cases. However, unlike its phylogenetically closely related species S. musiva, it is not a threat to fast growing hybrid poplar in plantation.

Availability of genome sequences for S. populicola, its sister species S. musiva, and other members of the genus Mycosphaerella will provide unique opportunities to perform comparative genomics of related Dothideomycetes fungal pathogens. Moreover the available genome sequence of its native host, P. trichocarpa, will prompt the analyses of the host-pathogen interactions. These genomic resources will improve our understanding of the mechanisms involved in fungal pathogenicity and host resistance which in turn will help to better manage forest diseases to ensure reliable supply of renewable wood fibre.