Mutualism between plant and fungus is observed almost all terrestrial plants. Plants make carbohydrates from CO₂ by photosynthesis and give them to fungal symbionts. On the other hand, fungi take soil nutrients such as phosphates and provide them to plants.
In this study, we discuss optimal resource allocation strategy when both plant and fungus control resource allocation of their own. Under some situations, the optimal amount of resource allocation can be independent of the strategy of the partner.