Does the chemistry of fungal pigments demand the existence of photoactivated defense strategies in basidiomycetes?

Personally, I strongly believe it does!

I am particularly interested in the yellow stainer (Agaricus xanthoderma), which secretes a yellow compound when it is cut. This yellow compound is an azobenzene derivative (4,4′-dihydroxyazobenzene), and it is the only known natural azobenzene!

It is actually a very curious thing. Azobenzenes are very studied in the field of photochemistry because they are used as photoswitches, but no one has studied (as far as I can tell) why this mushroom makes an azobenzene… Phototoxicity, perhaps??