The physiology of basidiomycete linear organs .3. Uptake and translocation of radiocaesium within differentiated mycelia of Armillaria spp growing in microcosms and in the field

Autoradiography and quantitative image analysis were used to measure Cs-137 distribution and translocation through mycelia of A. gallica Marxmuller & Romagn. and A. ostoyae (Romagn.) Herink growing in small microcosms in the laboratory. Rhizomorphs of A. gallica were labelled with Cs-134 the field, and the translocation of radiolabel measured after excavation and destructive harvesting. The flux of radiocaesium through rhizomorphs was estimated to be greater than through undifferentiated hyphae, and greater through rhizomorphs growing in the field than through rhizomorphs grown across homogeneous media in the laboratory. Differentiation within mycelia resulting in melanization or rhizomorph formation gave rise to increased heterogeneity in the Cs-137 distribution through laboratory microcosms compared with that through microcosms containing undifferentiated mycelia. Radiocaesium leaked from undifferentiated hyphae into the surrounding medium, but melanized regions of the mycelium appeared to be conservative for radiocaesium. These findings provide further evidence for the importance of filamentous fungi in determining the distribution and rate of release of radiocaesium currently present in the environment as a result of weapons testing and the accident at the Chernobyl nuclear reactor.