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Extraradical mycelium of the arbuscular mycorrhizal fungus Glomus lamellosum can take up, accumulate and translocate radiocaesium under root‐organ culture conditions
Author(s) -
Declerck Stéphane,
Dupré de Boulois Hervé,
Bivort Céline,
Delvaux Bruno
Publication year - 2003
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1046/j.1462-2920.2003.00445.x
Subject(s) - biology , hypha , mycelium , glomus , botany , fungus , mycorrhiza , chromosomal translocation , stele , symbiosis , phycomycetes , apoplast , obligate , spore , horticulture , cell wall , biochemistry , genetics , bacteria , gene , inoculation
Summary Radiocaesium enters the food chain when plants absorb it from soil, in a process that is strongly dependent on soil properties and plant and microbial species. Among the microbial species, arbuscular mycorrhizal (AM) fungi are obligate symbionts that colonize the root cortex of many plants and develop an extraradical mycelial (ERM) network that ramifies in the soil. Despite the well‐known involvement of this ERM network in mineral nutrition and uptake of some heavy metals, only limited data are available on its role in radiocaesium transport in plants. We used root‐organ culture to demonstrate that the ERM of the AM fungus Glomus lamellosum can take up, possibly accumulate and unambiguously translocate radiocaesium from a 137 Cs‐labelled synthetic root‐free compartment to a root compartment and within the roots. The accumulation of 137 Cs by hyphae in the root‐free compartment may be explained by sequestration in the hyphae or by a bottleneck effect resulting from a limited number of hyphae crossing the partition between the two compartments. Uptake and translocation resulted from the incorporation of 137 Cs into the fungal hyphae, as no 137 Cs was detected in mycorrhizal roots treated with formaldehyde. The importance of the translocation process was indicated by the correlation between 137 Cs measured in the roots and the total hyphal length connecting the roots with the labelled compartment. 137 Cs may be translocated via a tubular vacuolar system or by cytoplasmic streaming per se.