PARENT SESSION
Poster Session 38: Mutualism / Parasitism
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Modeling interactions between plants and arbuscular mycorrhizal fungi, with nutrient cycling and senescence.
Landis, Frank*,1, Fraser, Lauchlan2, 1 Biology Department, Akron, OH, USA2 Faculty of Science, Kamloops, BC, Canada
ABSTRACT- Arbuscular mycorrhizae are ubiquitous in the plant kingdom, but the complexity of their relationship is still poorly understood. Here, we present a simple model (implemented in Stella®)of the interaction between a plant and an arbuscular mycorrhizal fungus (AMF). As with other recent models, this one uses C:N:P stochiometry to regulate growth. However, it incorporates five novel features: 1) N and P cycle through a system composed of plant, fungus, litter, and soil, and organisms undergo senesence (negative growth) either as programmed or in response to nutrient deficiency. 2) organismal nutrient levels are flexible, vary independently, and are measured relative to organismal mass rather than each other. 3) allocation to organs is flexible, depending on tissue nutrient concentrations. 4) The mycorrhizal C:P exchange between plant and fungus is not tightly coupled. While in some models the C:P exchange ratio is fixed, here the C given by the plant and the P given by the fungus vary independently, depending on organismal needs and supplies. 5) The model incorporates efficiency exchange factors, so that not all of the C or P available may be taken up. This feature was suggested by variability of infection rates and growth responses demonstrated in the literature. The model's flexibility is demonstrated by its results. For instance, plant growth responses to different fungal ecotypes can be explained by simple differences in the nutrient exchange efficiency or allocation patterns. In another example, the model helps explain experimental data wherein small pot size and low soil P apparently caused the AMF to become parasitic, and where plants shrank and died towards the end of the experiment. More generally, this model can be used to model how varying nutrient pool sizes and plant properties affects mycorrhizal interactions, and how variations in mycorrhizal interactions affect both organismal growth and soil nutrient concentrations.
Key words: arbuscular mycorrhizae, plant-AMF interactions, modelling interactions, ecological stoichiometry