Fungi have ancient origins: the most recent evidence suggests that they appeared as early as one billion years ago. However, the fossil record available now is scarce and inconclusive, which makes scientists rely on mapping the evolutionary relationships of fungi using biochemical characters. The commonality found in fungal groups is their cell wall composition, namely, the presence of both chitin and alpha-1,3 and alpha-1,6-glucan (Kavanagh, 2017). Other characteristics include the organization of tryptophan enzymes, and synthesis of lysine (by the aminoadipic acid pathway). At first, fungi were classified as plants until in the mid-20th century, due to significant scientific advances, the three major kingdoms of multicellular eukaryotes (kingdoms Plantae, Animalia, and Fungi) were recognized as distinct.
In terms of evolution, the way fungi fit in the full picture is quite intriguing. It has been found that fungi cells are unexpectedly similar to human cells. In 1998, a group of scientists discovered that fungi split from animals about 1.538 billion years ago, while the split of plants from animals happened 1.547 years ago. The nine million year discrepancy shows that fungi are closer to animals than plants are (Torruella et al., 2015). One fact that proves this hypothesis is the presence of motile cells propelled by flagella, which is characteristic for both fungi and animals. What is interesting is that flagella helped fungi to make the evolutionary journey from water to land fork off from animals. Fungi were shedding ail-like flagella to move through the aquatic environment and reach land. In their new habitat, species were able to develop a variety of new mechanisms such as explosive volleys and fragrances for reproduction. The evolution of fungi helps scientists understand the evolution of species as a whole because they played such a big role in the transition from water to land.
The selected topic ignited my interest because I realized that I knew very little about the Fungi kingdom. Further research revealed that fungi are a natural resource whose potential to help humans has yet to be fully realized. In nature, these species play a variety of roles: they build mutually beneficial relationships with plants, supply them with valuable nutrients, and recycle dead organisms. It is estimated that out of thousands of fungi species present on Earth, only ten percent are well-explored. As of now, fungi are widely used in the production of beer, wine, cheese, and antibiotics. If scientists pay more attention to the species hidden from the view in habitats that are hard to reach, they might as well discover more uses in the food industry and healthcare. However, it should be noted that not all fungi are useful: some of them cause life-threatening infections, while others destroy crops. It is expected that further investigation will yield more knowledge on how to mitigate the harmful effects.
One of the questions that remains unanswered about fungi is exactly how they adapted to their new terrestrial habitat. It is possible that more research on this topic will lead to more valuable insights into divergence and survival mechanisms. Another interesting area of study that lacks evidence is the use of fungi in medicine. For example, extracellular vesicle (EV) was singled out for their potential use as protective immunogens (Rodrigues, Godinho, Zamith-Miranda & Nimrichter, 2015). As of now, however, the evidence is obscure and requires further investigation.
References
Kavanagh, K. (Ed.). (2017). Fungi: Biology and applications. Hoboken, NJ: John Wiley & Sons.
Rodrigues, M. L., Godinho, R. M., Zamith-Miranda, D., & Nimrichter, L. (2015). Traveling into Outer Space: Unanswered Questions about Fungal Extracellular Vesicles. PLoS pathogens, 11(12), e1005240.
Torruella, G., de Mendoza, A., Grau-Bove, X., Anto, M., Chaplin, M. A., del Campo, J.,… & Paley, R. (2015). Phylogenomics reveals convergent evolution of lifestyles in close relatives of animals and fungi. Current Biology, 25(18), 2404-2410.