Plant-fungal interactions: Niwot endophytic diversity and function

Plant-fungal interactions: Niwot endophytic diversity and function

Terri Tobias¹, Zach Gossage¹_, Jason Tuter¹, Richard Musser¹_, Robert Sinsabaugh², Katharine Suding³, Andrea Porras-Alfaro^1,2

¹Western Illinois University ²University of New Mexico ³University of California-Berkeley

Plants in the alpine tundra have a number of different adaptations to survive harsh environmental conditions. Among them are the associations with endophytic and mycorrhizal fungi. The main objective of this research was to examine the mechanism of transmission, diversity and function of seed and root-associated fungi at the Niwot Long Term Ecological Research Site in Colorado. We collected roots from G. rossii and D. cespitosa. In addition, seeds were collected from six dominant species. Seed and root fungal endophytes were isolated and identified by sequencing the Internal Transcribed Spacer rDNA. Dominant fungi were selected and tested in germination experiments using commercial plants. Alpine tundra plants harbor a community of endophytic fungi dominated by Ascomycota. A total of 51 endophytes were isolated from surface sterilized seeds, and 110 were isolated from surface sterilized roots. Dominant orders from the roots included Helotiales (23%), Hypocreales (23%) and Eurotiales (21%). Within Helotiales, dominant taxa were closely related to Phialocephala fortinii and Cryptosporiopsis ericae. The most common orders identified within the seeds were Capnodiales (38%) and Pleosporales (31%). Greenhouse experiments with a dominant root fungal isolate closely related to Philocephala fortinii, showed significant positive effects on both germination and plant growth in two commercially cultivated plants (Zea mays and Glycine max). To determine potential mechanisms of interaction between P. fortinii and the host plant, we conducted microarray analysis. Our preliminary results indicate that the fungus stimulated a number pathogen related genes particularly chitinases, peroxidases and stimulated a number of growth related genes such as expansin. At the molecular level little is known about the function of dark septate endophytic fungi. This research will not only help understand the role of these fungi in natural ecosystems but has the potential to provide new insights into plant management and fungal interactions.