What Lies Within: Evolution and ecological significance of a common conifer endophyte.

A wide variety of micro-organisms live hidden lives inside of plants. These micro-organisms are called endophytes, and often help their hosts survive environmental stress and disease, or can fend off animals and insects keen on eating the plant. Lophodermium piceae is an endophytic fungus found in up to 95% of the needles on spruce trees worldwide. Despite being extremely common throughout the northern Hemisphere, very little is known about this fungus. The iGran project uses molecular genetics to determine if Lophodermium piceae has evolved in tandem with spruce worldwide. Combined efforts with Canadian researchers have shown that European and North American L. piceae actually represent two separate and unique fungal species. In addition, more than 20 scientists have been involved in sampling spruce needles from 33 sites in 18 countries throughout Europe. We have used DNA-based biodiversity inventories to characterize the fungal community diversity across Europe and see that fungal communities track the evolutionary history of their hosts. In addition, we have now isolated thousands of fungi from these spruce needles, including more than 500 representatives of L. piceae. For each L. piceae isolate, we generated genomic 'fingerprints' that allow us to examine the effects of geography and extreme events like the last ice age on the genetic diversity of the fungus. Preliminary analyses suggest that while spruce trees have been genetically shaped by the last ice age, the Lophodermium fungi that grow inside its cells have not. To test whether L. piceae can protect its hosts from diseases and to identify microorganisms it interacts with, we have sequenced fungal DNA from hundreds of healthy and diseased spruce needles and see that the spruce rust fungus is less likely to cause symptoms when L. piceae is present.

Outcomes: The iGran project has resulted in the training of an early career female scientist in both classical mycology techniques, as well as cutting edge genetic methods for population genetics. During the course of the project, a new international collaboration was developed between the University of Oslo and the City University of New York to analyse the microbial community data generated. Impacts: As the final results of this basic research project have yet to be published, the results are not yet available to the general public and the broader research community, so societal impacts cannot be assessed.

Despite the fact it is likely the most common fungus in the Northern Hemisphere, very little is known about the evolutionary history and ecological function of Lophodermium piceae, a fungal endophyte that can infect up to 95% of spruce needles. Our project will take advantage of the ongoing revolution in molecular biology and sequencing technologies to examine whether strains from different hosts and locations are genetically distinct and to investigate whether the fungus' evolutionary history has been constrained by the dynamics of its hosts. The proposed project will combine metabarcoding and genotyping approaches to identify strains of L. piceae with possible antagonistic activities against foliar pathogens of spruce. We will then test these interactions in vitro with competition and growth experiments to further identify strains for metabolite profiling and possible industrial biocontrol applications. This project will greatly increase our knowledge of ecology and evolution in L. piceae, providing both results informative to fungal evolutionary theory, as well as ecological information with applied relevance. We expect the project will generate results and output valuable to both academic mycologists and the forestry industry.