Using radiocarbon to determine the mycorrhizal status of fungi


Measurements of 13 C in fungal sporocarps are useful in assessing mycorrhizal or saprotrophic status. Because 14 C measurements can indicate the age of fungal carbon (C) and mycorrhizal fungi depend closely on recent photosynthate, 14 C may provide additional insight into possible mycorrhizal status.

Sporocarps, needles, and litter from Woods Creek, OR, USA together with archived sporocarps were measured for 14 C content by accelerator mass spectrometry.

Known mycorrhizal fungi resembled current‐year needles ( Amanita , Cantharellus and Gomphidius ) or atmospheric CO 2 ( Tuber ) in 14 C and indicated an average age of 0–2 yr for incorporated C, whereas saprotrophic genera ( Pleurocybella , Lepiota and Hypholoma ) were composed of C at least 10 yr old. Of genera tentatively considered mycorrhizal from previous work with 13 C, only Otidia and Sowerbyella appeared mycorrhizal from 14 C measurements, whereas Aleuria , Clavulina , Paurocotylis and Ramaria (sensu lato ) consisted of older carbon and were presumably saprotrophic.

14 C clearly separated known mycorrhizal or saprotrophic fungi and indicated 13 C measurements should be interpreted cautiously on species of unknown status. 14 C results for needles and mycorrhizal fungi suggested that C sources other than atmospheric CO 2 may contribute small amounts of C. Possible sources include storage of carbohydrates and amino acids, organic nitrogen uptake, and incorporation of soil‐respired CO 2 by anaplerotic or photosynthetic pathways.


Earth Systems Research Center

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New Phytologist



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