A novel pathogenic fungus causing leaf spot disease in Arctic plants was reported on Ellesmere Island. Although there are a few reports on plant pathogens in Arctic ecosystems, this study showed that even in the Arctic, the regional location and the host species-level differences drive pathogenic diversity.

Tsukuba, Japan—Ellesmere Island (76°N-83°N) is one of the northernmost islands in the world, along with Greenland and Spitsbergen Island. More than 100 species of vascular plants are distributed across this island in the ice-free areas in summer. However, there has been little research on fungal diseases in these plants.

In this study, a researcher at the University of Tsukuba discovered a pathogenic fungus that forms an unique black stroma (reproductive organs of fungi, such as mushrooms) on the leaves of the Arctic willow, which is a dominant plant on the island. The morphological characteristics of fungus were different from those of any related species discovered as yet in terms of the key points for species identification, namely, the size of the spores and shape of stroma. Molecular phylogenetic analysis also supports the uniqueness of this specimen, and it has been described as a novel species of fungus of the genus Rhytisma.

This study has shown that even in the Arctic, the regional location and the host species-level differences drive the diversity of the pathogens. Further data on Rhytisma spp. from other regions in the Arctic will help us understand how they had spread across the Arctic region with their hosts and how they survived in the tundra ecosystem.

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This work was supported by the Arctic Challenge for Sustainability (ArCS) Project (JPMXD1300000000) and the Arctic Challenge for Sustainability II (ArCS II) Project (JPMXD1420318865) by the Japanese Ministry of Education, Culture, Sports, Science, and Technology. This work was also supported by Sumitomo Foundation Grant for Environmental Research Projects (grant 2230056).

Original Paper

Title of original paper:

The northernmost plant pathogenic fungus, Rhytisma arcticum sp. nov.: Morphological and molecular characterization of a novel species from Ellesmere Island, Canada

Journal:

Forest Pathology

DOI:

10.1111/efp.12818

Correspondence

Assistant Professor MASUMOTO Shota
Institute of Life and Environmental Sciences, University of Tsukuba

Related Link

Institute of Life and Environmental Sciences