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Contributed Talk

Session: : Mycorrhizae 3

COS 179-1 - Diversity in mycorrhizal function among AM fungi species

Wednesday, August 9, 2023
10:00 AM – 10:15 AM PDT
Location: E146
Abstract: Though mutualisms are often characterized as simply positive species interactions, the resources exchanged in mutualisms can be diverse. For example, arbuscular mycorrhizal fungi (AMF) provide phosphorus, nitrogen, and water to their plant hosts in addition to indirect benefits, including improved soil structure. Though we know that AMF vary in their overall growth effects on plants, we know little about how different AMF species may vary in the specific benefits they provide to plants. We also know that there is variation in traits among AMF species, but there are limited tests of how well these fungal traits may predict plant responses. To test these ideas, we isolated nine species of AMF from prairie soils and tested their effects on the growth of a common host plant (Big Bluestem, Andropogon gerardii). We found that plant growth response changed over time, with some fungi having little effect on growth at any time, some showing reduced growth early in the experiment and exponential growth later in the experiment, and other fungi supporting logistic growth with large effects on plant growth early in the experiment and limited effects on plant growth late in the experiment. Fungi species also varied in their effects on plant root:shoot ratio independently of their effects on plant growth. Together these two results suggest variation in the cost:benefits of the mycorrhizal mutualism among different AMF species and likely variation in the types of benefits plants gain. We also found that total hyphae in the soil was a better predictor of plant response than the formation of hyphae, arbuscules, or vesicles within the plant root, indicating that the ability of the fungi to expand the volume of soil from which plants can draw nutrients is among the primary benefits plants derive from the mutualism. Overall, we show complexity in the mycorrhizal mutualism, with the timing and type of benefits plants receive varying among their fungal partners.