Dear Balraj, really it is the matter of experiment to test what factors are responsible for their growth in the stressed condition. Usually, species have their own adaptability to grow in their environment. For example, Desert Truffles grow in the desert ecosystem. They are adjusted with the eco-environment of desert. It can not be predicted all on a sudden the mechanism of growth of the fungus. It should be experimented scientifically to investigate the know-how of the truffle growth. Rather you can design an experiment regarding the factor with the desired fungus.

It might be macrofungus constituents which express diffrentially in stress condition or some signaling cascade.....i am not sure about that??