I want to know the trigger behind the change of asexual to sexual ectomycorrhiza when symbiosis with a tree root is formed. As ectomycorrhiza attaches itself to a root, it forms a relationship wherein phosphorous to the tree/plant is exchanged for glucose to the fungus. When this symbiosis occurs, the fungus, which is normally asexual, becomes sexual(male/female components) and buds form as a result. Thus I could hypothesize that if glucose is the catalyst, I could saturate the soil and cause this reaction. However, I am not sure what the actual chemical signal is, or if there is an unforeseen factor causing this change. Does anyone have any knowledge on the subject of what the aforementioned catalyst would be?