Cool New Paper: Marine Fungi

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I don’t know much about marine fungi. That’s not only due to my intellectual laziness, but also because they’re genuinely understudied. There are over 77000 terrestrial fungi, but not over 500 marine species (Hawksworth, 2001), despite being widely acknowledged as being very diverse (pers. comm. from a shroomologist friend). The ones that are known are known mostly from mangroves (Raghukumar, 2007).

Most of them are described only from isolated spores, with little being known about the vegetative morphology. As for their biology, it’s known that primary marine fungi, i.e. those that originated in the oceans, not on land, are obligate parasites (Moss, 1986), some of them effective enough that some shrimp and lobsters host symbiotic bacteria that produce anti-fungal compounds to protect the crustacean embryos (Gil-Turnes & Fenical, 1992). Some other marine fungi, those that returned to the oceans secondarily, are free-living, such as the arenicolous fungi that live in sand pores. Some of them live on decaying wood floating around in the water (Kohlemeyer & Kohlemeyer, 1979), and other live on corals, where they may become pathogenic in the face of rising temperature and coral bleaching (Holmquist et al., 1983).

Some marine fungi even live on terrestrial plants. Such is the case with the food source of the snail Littorina irrorata. This is an intertidal snail, living in the marshy area which gets flooded at high tide. The snail purposely injures Spartina plants that grow there. When the high tide comes, ascomycete spores deposited in the marsh and found in the water will get pushed into and colonise the wound, giving the snail its main food source – it’s a farming system (Silliman & Newell, 2003).

It’s surprising that it seems that marine fungi can survive on land, when the soil is suitably saline (Rao et al., in press).

Interest in marine fungi nowadays is rising quite a lot not only out of the systematics and phylogenetics corners, but also from the biotech fields, as they’ve been shown to be a good source of all sorts of useful chemicals, much like their terrestrial counterparts (Bhadbury et al., 2006). For example, a species of Fusarium isolated from a seaweed harbours a chemical that may have anti-cancer effects (Ebel, 2006). Similarly, Ascochyta salicorniae produces a compound which could have anti-malarial effects (Osterhage et al., 2000).

Some authors interpret several Ediacaran fossils as marine fungi (e.g. Peterson et al., 2003), but given that they don’t share any crown-group characters, this is pretty contentious; it can be that the Edicarans are stem-group fungi though. Confirmed fossil marine fungi do exist though, most prominent of which are the Doushantuo lichens described by Yuan et al. (2005).

That’s just about all I know about marine fungi. The new paper I will be reading before I go to sleep tonight will give me much more information:

Richards TA, Jones MDM, Leonard G & Bass D. 2012. Marine Fungi: Their Ecology and Molecular Diversity. Annual Review of Marine Science 4, 495-522.

I’ve only read the abstract and skimmed the rest, but given that it’s an Annual Review paper, it’s bound to be excellent. The part that immediately attracted me was the phylogenetic part and I skimmed that in a bit more detail than the rest. It’s a meta-analysis of already-available data and found a whopping 36 new lineages! 24 of them branch out within a single taxon, the chytrids. I can’t comment on the significance of that last point, but it seems pretty obvious to me that a potentially really fruitful avenue for fungal diversity research is to simply scoop up random seawater and analyse all the SSU rDNA found in there. Most of these things can’t be cultured, but their genetic material can always be magnified (although this kind of environmental sequencing is technically challenging, at least afaik).

References:

Bhadbury P, Mohammad BT & Wright PC. 2006. The current status of natural products from marine fungi and their potential as anti-infective agents. Journal of Industrial Microbiology & Biotechnology 33, 325-337.

Ebel R. 2006. Secondary metabolites from marine derived fungi. In: Proksch P & Müller WEG (eds.). Frontiers in Marine Biotechnology.

Gil-Turnes MS & Fenical W. 1992. Embryos of Homarus americanus are Protected by Epibiotic Bacteria. The Biological Bulletin 182, 105-108.

Hawksworth DL. 2001. The magnitude of fungal diversity: the 1.5 million species estimate revisited. Mycological Research 105, 1422-1432.

Holmquist GU, Walker HW & Stahr HM. 1983. Influence of Temperature, pH, Water Activity and Antifungal Agents on Growth of Aspergillus flavus and A. parasiticus. Journal of Food Science 48, 778-782.

Kohlemeyer J & Kohlemeyer E. 1979. Marine mycology: The higher fungi.

Moss ST. 1986. The Biology of Marine Fungi.

Osterhage C, Kaminsky R, König Gm & Wright AD. 2000. Ascosalipyrrolidinone A, an Antimicrobial Alkaloid, from the Obligate Marine Fungus Ascochyta salicorniae. The Journal of Organic Chemistry 65, 6412-6417.

Peterson KJ, Waggoner B & Hagadorn JW. 2003. A Fungal Analog for Newfoundland Ediacaran Fossils? Integrative & Comparative Biology 43, 127-136.

Raghukumar S. 2007. Marine eukaryote diversity, with particular reference to fungi: Lessons learned from prokaryotes. Indian Journal of Marine Science 35, 388-398.

Rao S, Chan Y, Lacap DC, Hyde KD, Pointing SB & Farrell RL. In press. Low-diversity fungal assemblage in an Antarctic Dry Valleys soil. Polar Biology, in press.

Silliman BR & Newell SY. 2003. Fungal farming in a snail. PNAS 100, 15643-15648.

Yuan X, Xiao S & Taylor TN. 2005. Lichen-Like Symbiosis 600 Million Years Ago. Science 308, 1017-1020.