A new open access paper reveals that a species of marine lichen hosts a range of additional photosynthetic partners, which according to researchers could be vital for survival in the harsh conditions of the rocky shore. 

Marine Biological Association (MBA) Senior Research Fellow Dr Michael Cunliffe and Postdoctoral Research Associate Dr Nathan Chrismas are co-authors of the research paper featured in the Journal of the Marine Biological Association of the United Kingdom (JMBA)

For a long time, people thought that lichens were mostly a two-way symbiosis between a fungus and single photosynthetic partner, but modern molecular biology methods are starting to show that several different photosynthetic partners or ‘photobionts' are sometimes involved. 

The study showed that some samples of Lichina pygmaea - also known as black pygmy lichen - host a range of photobionts including marine and freshwater cyanobacteria (blue-green algae) and marine eukaryote algae which may help the lichen to survive the harsh fluctuating environmental conditions of the intertidal zone.

Dr Chrismas said: “The results were really exciting as we showed that our Lichina pygmaea samples appear to have at least two additional photobionts that haven’t been reported in previous studies. 

What’s really interesting is that a lot of these photobionts are marine species, which is really important for helping Lichina pygmaea survive in the intertidal zone where it's covered in seawater twice a day.”

The paper was inspired by MBA researcher Gladys Naylor who almost a century ago published her JMBA study on Lichina pygmaea distribution around Plymouth using samples from the same locations.

Dr Chrismas said: “Gladys Naylor first described the distribution of Lichina pygmaea in the Plymouth area way back in 1929. We wanted to bring that link between the MBA, Plymouth, and this amazing lichen right up to date using modern molecular biology techniques.”

Lichens are incredibly important organisms that cover between 6 and 8 % of the earth’s surface. They contribute to carbon and nitrogen cycles and many of them produce complex compounds that can be used to produce novel antibiotics, but the mechanisms that allow them to survive in marine environments are still relatively unknown. 

Dr Chrismas said “We’re really excited in the Cunliffe group to be working on these fascinating organisms and helping to understand how fungi have adapted to living in marine ecosystems.”

Complex photobiont diversity in the marine lichen Lichina pygmaea can be accessed in the latest edition of the JMBA. 

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Oct 1, 2021 By nerblo