Effects of nutrient environment on soil fungal interactions
Multiple species of fungi coexist in soil. They constantly engage in warfare for food sources and territory, and have developed different strategies to survive and keep themselves fed. So called mycorrhizal fungi form symbioses with plants. The plants provide them with sugars and the mycorrhizal fungi use them to grow and scavenge soil for other nutrients that they transport back to the plants. Because the mycorrhizal fungi are not alone in this search, they constantly compete with free-living saprotrophic fungi for who of them is faster and more efficient at obtaining the nutrients. To succeed in this competition, both mycorrhizal and saprotrophic fungi have also developed complex chemical weapons to prevent the opponents from colonizing nutrient sources and growing. As a result of this fungal warfare, the cycling of dead organic matter is affected and is balanced between it being deposited into the depths of soil or being broken down and respired into the atmosphere as carbon dioxide. Variations of environmental conditions induced by climate change and human activity disturb this balance. So far, it is unknown which factors and practices will be decisive in whether the fungi contribute to anthropogenic carbon dioxide emissions or mitigate them by depositing carbon in soil. It is clear though, that understanding how fungi work, interact and compete can give us means to nudge them into doing the latter, which would help fighting climate change.
In this Master level project (30 -45 ECTS, but can also be adjusted to 60 ECTS) project, interactions between ectomycorrhizal and saprotrophic fungi under different nutrient conditions (carbon and nitrogen source type and amount) will be investigated at the level of fungal mycelia in laboratory agar cultures and at the level of single hyphae in soil chips. The soil chips are made from transparent glass and rubber materials, and with tiny structures, hundreds of times smaller than the thickness of a single human hair, engraved in them and mimicking the complexity of real soils. Being transparent, the soil chips provide a window to the underground world of fungi. Observations of fungal growth and morphology of the mycelia and hyphae will be monitored by using optical microscopy. This will allow to judge on how different pairs of fungi respond to competition and how changing nutrient conditions in the environment affect this response. In turn, this will shed light on the complex interactions and dynamics that shape the circle of life driven by fungi in soils.
Welcome to contact Milda Pucetaite at Dept. of Biology to discuss the project in more detail.
E-mail: milda.pucetaite@biol.lu.se