Photo-activated Defense Strategies in Fungi

All living organisms are to some extent in competition with each other for nutrients and living space. Since Darwin we know that the better-adapted species survives. Evolutionary, the best survival and defense strategies have prevailed with the existing species. For plants and fungi, the defense strategies are based on chemical ingredients that, for example, make the fruit of the plant inedible to a predator by a bitter or pungent taste. In addition to the flavoring ingredients, there are also those that are lethal in large quantities. Particularly insidious are those ingredients that unfold their full effect only in combination with another factor. Such factor can be the sunlight for colored ingredients. For example, when white horses eat from the St. John`s Wort, they suffer from severe skin rashes in the sunlight. The responsible, light-activated ingredient is hypericin, which gives the oily extract of the yellow flowers its red appearance. For the plant kingdom, many other yellow or red species are known that damage the predator only in sunlight. For mushrooms, however, not a single case is described. This is particularly idiosyncratic, if we consider the abundance of colored mushrooms that sprout in the shady forest during autumn. In the past it has been suggested that the colors hold a sun-protective function. But does it need sun- protection in the shady forest? We, instead, hypothesize that mushrooms defend themselves with the added help of sunlight. In the shady forest, the fungus is not damaged by sunlight. But his predator, the fly for example, is affected as soon as it flies into the sunlight. As our preliminary research confirms this hypothesis. Thus, we further believe that the light-activate-able fungal constituents will be useful in the form of novel, light- activated drugs for our society. As part of the project, we first want to develop tests that help us to find mushrooms that have an increased effect in the light. Later, these fungal species will be examined to decipher the chemical cause and to test their pharmacological potential. Intended medical applications are tumors and multi-drug resistant bacteria. For both areas new pharmacological weapons are urgently needed because our current ones are either too imprecise or lose their effect due to occurring resistances more and more. A therapy based on light allows a punctual treatment and thus high-doses while the probability of growing resistances is due to the external activation factor, i.e. visible light, is negligible. In summary, with this project we want to unravel the subtitle defense mechanism of mushrooms in order to gain a medical benefit for us humans.

Light-activated defence strategies in fungi -An overlooked source of novel light-activated drugs. All living organisms compete to some extent with each other for nutrients and habitat. Since Darwin, we have known that the better adapted species survives. In evolutionary terms, the best survival and defence strategies have also prevailed with speciation. For plants and fungi, the latter are primarily based on chemical substances that, for example, make the plant's fruit inedible to a predator by giving it a bitter or pungent flavour. In addition to ingredients that influence the flavour, there are also those that are lethal in larger quantities. Particularly dangerous are these ingredients that only develop their full effect in combination with another factor. Such an additional factor can be sunlight for coloured ingredients. For example, white horses suffer from severe skin rashes in sunlight when they feed on St. John's wort. The active ingredient responsible, which is only active in sunlight, is hypericin. Many other yellow or red species are known in the plant kingdom that only harm the predator in sunlight. However, for the basidiomycetes commonly referred to as mushrooms, there is not a single case described. This is particularly peculiar considering the abundance of coloured fungi. In the past, it has been suggested that the colours provide protection from the sun. But is sun protection needed in a shady forest? As part of the PhotoFungal project, the hypothesis was tested that fungi also defend themselves with the additional help of sunlight. In shady forests, the fungus is not harmed by sunlight. However, its fungivore, the fly, for example, is affected as soon as it flies into the sunlight. Our research results showed that the fungi produce various light-activated compounds and that an increased content of these can be found in the lamellae of the fungus. We also investigated the extent to which these light-activated fungal compounds could be useful in the form of novel, light-activated medicines. As part of the project, tests were initially developed that helped us to find species of fungi that show an increased effect in the light. As the webcaps (Cortinarius) were particularly active, various species of this genus were analysed more closely and the chemical cause deciphered. We were able to show that anthraquinones are the active principle and have a high pharmacological potential when exposed to light. One dimeric ingredient was highly active against tumour cells and other monomers against multi-resistant microorganisms. Novel pharmacological weapons are urgently needed for both areas, as our current ones are either too imprecise or are increasingly losing their effect. To summarise, this project has enabled us to understand nature a little better and derive potential medical applications for us humans.