Have you ever picked a fallen leaf off the ground and wondered where it came from? Stared at the trees changing colors and losing their leaves above you, as those leaves ultimately find their way to the massive piles young kids like to jump into? Well, ever since I started delving into the strange and wonderful world of plants and the fungi that live on them, I haven’t been able to look at leaves the same way. My research focuses on tiny fungi that live inside of plant leaves. Known as ‘endophytes,’ these little critters form some of the most mysterious associations on the planet. Each plant leaf can be colonized by up to hundreds of different tiny fungi, which grow locally inside the plant tissues. Where do these fungal endophytes come from, I ask? If we can’t see or hear them, how do we determine their effects on the different plants they live on? This is a big dilemma of my research. By extracting DNA from these fungi and using specific stretches of the fungal genome as a target, I am able to collectively identify the fungal inhabitants of my research plants – no matter their size, abundance, or location within a single host.
One of my main research projects uses Switchgrass as a model system (aka an “example system”) for studying fungal colonizers. Switchgrass is an excellent plant to study for several reasons. Switchgrass is a tallgrass plant species that grows in most states east of the Rockies. It requires very little water or fertilizer in order to grow, yet it can still produce impressive yields of leaf and stem mass. Because of its robust characteristics and widespread distribution in the United States, Switchgrass is currently a top biofuel candidate being studied by the government.
For my research, however, I want to figure out which fungal endophytes live on Switchgrass and why. Do different fungal species live on different varieties of Switchgrass? Just like there are different crop varieties within the same domesticated species (e.g., ‘Herbicide-resistant’ and ‘Sweet’ corn varieties), there are different varieties within the same species of wild, non-crop plants as well. Switchgrass has many natural varieties, but are they colonized by different fungal endophytes? For example, does the Switchgrass variety normally found in southern Indiana interact with different fungi than the Switchgrass variety found in southern Illinois? Or does where they are physically planted determine which fungi they interact with, regardless of what variety they are?
For my research, I work to understand what matters more to plants and their interaction with fungi: who you are, or where you are? I planted replicate plants from three different Switchgrass varieties in three different locations across the Midwest. I used DNA-based techniques to identify the fungal species in Switchgrass leaves. I found that “where you are” matters much more to how these communities of tiny fungi colonize and interact with Switchgrass plants. Most of the Switchgrass plants growing at any of the three study sites were colonized by the same groups, or ecological communities, of fungi. My work has important implications for considering how both agricultural and wild varieties of plant species can live and interact with different fungi, based on where they are being grown. In the future, I would like to explore more how these differences in tiny fungi communities can influence the health and yield of the plants they live on.