Lichens may be a symbiosis of three organisms; a new Order of fungus named


Susan Lawler, La Trobe University

There is big news in the world of lichens. These slow growing organisms have long been known to be a collaboration between a fungus and a photosynthetic algae or cyanobacteria. A recent publication in Science may have changed all that.

Researchers have discovered another fungus living in the tissues of lichens. Unlike the dominant fungal type, also known as Ascomycetes, the new fungus is a Basidiomycete that exists as single cells, more closely related to yeast. A survey has found these new fungal cells in 52 genera of lichens, raising the prospect of a previously undetected third partner in the ancient symbiosis.

Interestingly, despite many attempts, it has never been possible to synthesise lichen in the laboratory by combining the two known partners, and now we might know why. Lichenologists have always recognised a mycobiont (fungal partner) and a photobiont (the photosynthetic organism that makes food) and now we may have to find a word for the new fungal component.

Toby Spribille of the University of Graz in Austria and his colleagues were trying to understand why two species of lichen that were made up of the same species of mycobiont and photobiont were differently coloured and contained varying levels of a toxin known as vulpinic acid.

Using an approach that examined the messenger RNAs produced by the organism, they tried to find the genes that produced the toxin, but neither the mycobiont or the photobiont had genes that matched the transcript. By broadening their search to include other types of fungi, they found genes belonging to a rare fungus called a Cystobasidiomycete.

Unable to see the cells responsible for this unusual finding, they used fluorescent in situ hybridisation (FISH) to light up cells containing genes for the algae, the ascomycete and the cystobasidiomycete. By linking different colours to each organism, they produced videos showing the distribution of each cell type. The new fungus existed as single cells inside the cortex, where it may play a structural role as well as providing chemical defence.

It is hard to overstate the importance of this discovery. Spribille was quoted in the New York Times as saying that lichens are as diverse as vertebrates. And yet we did not know until now that the symbiosis that allows lichens to exist has more than two partners.

The authors have described a new order of fungi called the Cyphobasidiales. It is not everyday that scientists are able to add new taxa at such a high level. It is like discovering the Primates. By creating a phylogenomic tree and applying a molecular clock, they found that this group has been around for 200 million years, probably since the beginning of lichens.

The 52 genera that have been examined thus far are widespread (on six continents) but are still a small portion of lichens, so there may be more to discover. Interestingly, the continent that is not included is Australia. Perhaps we do not have enough lichenologists to provide samples to the international community. It is possible that some lichens do not contain this new order of fungi. What is not in doubt is that now scientists will be looking at lichens more closely.

Lichens grow very slowly. Individuals can be hundreds or even thousands of years old. Now it seems that our knowledge of this ancient symbiosis has also grown slowly, as it has taken 150 years to find the third partner.

Given the sophisticated techniques required to untangle this conundrum, I suppose it was not possible to know about the silent partner, the yeast in the mix, until now. But it certainly gives rise to some exciting science.

The Conversation

Susan Lawler, Senior Lecturer, Department of Ecology, Environment and Evolution, La Trobe University

This article was originally published on The Conversation. Read the original article.

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The Wilderness Society Being Torn Apart


Infighting is threatening to destroy the environmental group, ‘The Wilderness Society.’ A court battle now looms in order to sort out the mess that has become The Wilderness Society.

This is a group that I have supported in the past and depending on the outcome of the court case and what then happens with The Wilderness Society will determine whether I support the group again.

The Wilderness Society is a well known environmental group in Australia. It was formed to fight the Franklin Dam project in Tasmania in the 1970s.

The following link is to an ABC news article reporting on the story:

http://www.abc.net.au/news/stories/2010/05/03/2889021.htm

The Wilderness Society website:

http://www.wilderness.org.au/

The video below is a reflection on the Franklin Dam project protest.

 

Earth Day: April 22


Earth Day is about the earth and the people who live on it. The Earth Day Network believes that all people, no matter who they are, have a right to a healthy and sustainable environment. Those who support Earth Day are a veritable who’s who of environmentalism. The network not only educates and increases awareness of environmental issues, it also actively seeks to bring about change in order to achieve a healthy and sustainable environment.

Earth Day is celebrated on the 22nd April each year, with supporters getting involved in all manner of environmentally responsible activities.

Find out more about Earth Day and the Earth Day Network at:

http://www.earthday.org/

THINKING ABOUT MY NEXT TRIP


It has been quite some time since my last holiday. I expect I can do a day trip or two before my next holiday. However, it is time to start planning a more substantial holiday. I need to do this in order to get myself motivated and to have something to work towards. My holidays have always been better when I have planned ahead for them.

So, step number one is to come up with a destination or perhaps a route. I need a planned itinerary, a place to go or some plan for my holiday. So that is the first step.