Three-Way Mutualism: A Clue to Pre-Fall Viruses

I came across an article I had pulled out of the journal Science back in 2007, and it reminded me of a very interesting form of mutualism that I had completely forgotten about. In case you aren’t familiar with the term, mutualism is a situation in which two or more organisms work together so that they each benefit. It is quite common throughout creation. For example, one of the ways you get the Vitamin K that you need is through a mutualistic relationship between you and some bacteria that live in your intestine. You provide them with food and housing, and in exchange, they provide you with Vitamin K. Well, this article discusses a mutualism that involves three partners, and in order for the situation to work, all three partners must be present. Amazingly enough, the partners are a fungus, a plant, and a virus!¹

In the article, the scientists were studying Dichanthelium lanuginosum, a grass that is often called “panic grass.” While this grass can grow in many places, it actually flourishes in the geothermal areas of Yellowstone National Park, where the soil is far too hot to support most plants. When scientists initially studied this plant, they found its roots infected with a fungus, Curvularia protuberata. Now this is not unusual at all. Indeed, roughly 80% of plant species that have been surveyed participate in a mutualistic relationship with at least one species of fungus.² Typically, the plant provides sugars for the fungus, and the fungus absorbs minerals from the soil and gives them to the plant.

It was assumed for many years that the fungus found in the roots of panic grass provided the plant not only with minerals, but with something that allows the grass to tolerate soil that is simply too hot for other plants. The authors of the Science article found that this is only a partial explanation.

The authors did experiments that showed the fungus does not always allow the grass to tolerate hot soils. Instead, for the grass to be able to grow in hot soils, the fungus that infects the grass must, in turn, be infected by a virus. Only then will the plant be able to grow in hot soils. Indeed, the title of the article in Science is “A Virus in a Fungus in a Plant: Three-Way Symbiosis Required for Thermal Tolerance.” (“Symbiosis” is a more general term that includes mutualism.)

I have blogged about mutualism before (here, here, and here), and I think it provides strong evidence that organisms have been made for each other. Indeed, mutualism is one of the many aspects of nature that indicate the amazing design ingenuity of the Creator. What caught my eye about this article was the fact that because one of the participants in the relationship is a virus, it could help creationists learn a lot more about the genesis of viruses.

There are a lot of different kinds of viruses (DNA viruses, double-stranded RNA viruses, single-stranded RNA viruses, retroviruses, etc.), and it is possible some of them have arisen since creation. Indeed, as I have mentioned previously, Dr. Peter Borger has a very interesting hypothesis that retroviruses came from existing genomes. He thinks that there are variation-inducing elements in all genomes and that retroviruses arose from them. While it is an intriguing possibility, it is only plausible for retroviruses.

The virus involved in this mutualism is not a retrovirus, so it must have come about by some different means. It is possible that some kinds of virus were a part of the initial creation, but at that time, they did not cause disease. While it may seem odd to think of a virus that doesn’t cause disease, it actually makes a lot of sense. There are some bacteria that cause disease, but there are many bacteria that are benign, and there are actually a few that are beneficial. Thus, it isn’t much of a stretch to think that viruses can also be benign and/or beneficial. Indeed, we know the virus that participates in this three-way mutualism is beneficial – without it, both the plant and the fungus would die.

If some kinds of viruses were initially created to be beneficial, what kind of roles would they play in creation? Well, Dr. Alan Gillen discusses a proposal made several years ago by J.W. Francis:

Francis proposes that microbes and viruses were created as a link between macroorganisms and a chemically rich, but inert, physical environment, providing a surface (i.e., substrate) upon which multicellular creatures can thrive and persist in intricately designed ecosystems. Microbes are designed for symbiotic relationships with both macroorganisms and other microbes and viruses.³

In other words, viruses could have been initially created specifically to form mutualistic relationships that would allow macroscopic organisms (like plants) to flourish in places they normally wouldn’t be able to tolerate, as is the case in this three-way symbiosis. Then, once the Fall corrupted creation, some beneficial viruses could have experienced mutations that resulted in them becoming pathogenic.

This explanation makes a lot of sense for bacteria, because there are many bacteria that perform vital roles in creation. Without them, other organisms would not be able to survive. Since we know that many bacteria have specific roles in nature, it is not hard to believe that they were initially created to serve those roles, but over time some of them were corrupted, resulting in some pathogenic bacteria. Well, if it turns out there are a lot of viruses like the one that participates in this three-way mutualism, the explanation could make just as much sense for many kinds of viruses.

I wonder how many more examples of mutualistic viruses exist? I think some creationist virologists should go looking…

REFERENCES

1. Luis M. Márquez, et al., “A Virus in a Fungus in a Plant: Three-Way Symbiosis Required for Thermal Tolerance,” Science 315:513-515, 2007 (Avaliable online with subscription)
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2. B. Wang and Y.-L. Qiu, “Phylogenetic distribution and evolution of mycorrhizas in land plants,” Mycorrhiza 16:299-363, 2006 (Avaliable online for purchase)
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3. Alan L. Gillen, “Microbes and the Days of Creation,” Answers Research Journal 1:7-10, 2008 (Avaliable online)
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