Recently, it’s been discovered by a group of student researchers at the University of Göttingen, Germany that the cells found in fungi that are typically responsible for the reproductive structures of the organism during overwintering periods also play a large role in the production of chemicals that protect the fungi from potential predators.
Due to the fact that fungi cannot move on its own in order to evade predators, they use chemicals to defend themselves by producing secondary metabolites. Secondary metabolites are not essential to the life of organisms, however they absolutely aid the fungi in their pursuit of avoiding predators and are beneficial for the organism’s survival. Some fungal secondary metabolites can even be fatal when eaten by humans, however most only consist of unappealing odor, color, and other physical attributes. Though not classified as plants, fungi and plants share many qualities and their production of secondary metabolites happens to be one of them and they produce them for the exact same reason too (their cells also both have a cell wall; that’s not really relevant but I wanted to include that because I find it interesting).
The proteins that are largely responsible for the production of most of these secondary metabolites are located in the Hülle cells of the fungus. Hülle cells play a vital role of the development and structure of fungi’s reproductive mechanisms. In order for the production of these secondary metabolites to be limited to that of an appropriate quantity, the “velvet complex” acts as a regulator for the pathways needed for production itself. A nearly perfect system. A flaw though, is if this process is interrupted for some reason, the organisms system of protection and its reproductive structures will both be impacted severely. Due to the fact that the protective chemicals use the reproductive structures as its main hub of production and storage, an interruption of the process would lead to a lack of development in both. This would be devastating to the organism not only because it is now vulnerable to predators but this lack of development of reproductive structures also inhibits the organism’s ability to reproduce.
In the study, researchers observed woodlice and other arthropods that are predators of the fungi (they used A. nidulans for this study, a self fertilizing fungus (pictured above)) and how they respond to these secondary metabolites. It’s important to note that in this case the chemicals were not toxic to the arthropods, they simply made the parts of the fungus containing secondary metabolites undesirable for consumption (I include that not only to provide ethical clarity regarding the study for any readers that are curious but also to provide more information about the study as a whole). What the researchers found was that the predators only consumed parts of the organism that did not possess any secondary metabolites and they left areas that had many, such as its reproductive structures, completely alone. While I, like presumably many, don’t find this particularly surprising on the one hand; on the other it confirms that there is some sort of significance to the chemicals being produced and stored primarily in this region of the organism. Previous to this study, the importance of Hülle cells regarding the protection of fungi was completely unknown. In science, no matter what the field, discovery of any kind is a step in the right direction.
This study has shown that despite fungi’s immobility and lack of obvious protection, it has evolved in such a way that its system of shielding itself from potential threat is sophisticated, effective, and deceiving.