Towards the conservation of ectomycorrhizal fungi on endangered trees: native fungal species on Pinus amamiana are rarely conserved in trees planted ex situ
Ectomycorrhizal (ECM) symbiosis is essential for the survival of both host trees and associated ECM fungi. However, during conservation activities of endangered tree species, their ECM symbionts are largely ignored. Here, we investigated ECM fungi in ex situ populations established for the conservation of Pinus amamiana, an endangered species distributed on Yakushima Island, Japan. Our objective was to determine whether ECM fungi in natural forests are conserved in ex situ populations on the same island. In particular, we focused on the existence of Rhizopogon yakushimensis, which is specific to P. amamiana and the most dominant in natural P. amamiana forests. Molecular identification of ECM fungi in resident tree roots and soil propagule banks indicated that ECM fungal species native to natural forests were rarely conserved in ex situ populations. Furthermore, R. yakushimensis was not confirmed in any of the resident root or spore bioassay samples from the ex situ populations. Thus, ECM fungal spores may not be effectively dispersed from natural forests located on the same island. Instead, ECM fungi distributed in other geographical regions occurred more frequently in the ex situ populations, indicating unintentional introductions of non-native ECM fungi from the nurseries where seedlings were raised before transplanting. These findings imply that the current ex situ conservation practices of endangered tree do not work for the conservation of native ECM fungi, and instead may need modification to avoid the risk of introducing non-native ECM fungi near the endangered forest sites.
KeywordsConservation Endangered host Ex situ conservation forest Specific ECM fungus
We would like to thank Kenshi Tetsuka and Toshihiro Saito for supporting our field survey and providing information about Pinus amamiana; and Helbert at the University of Tokyo for helping with the field sampling; Yakushima Forest Ecosystem Conservation Center for the permissions of field sampling.
This work was supported in part by Japan Society for the Promotion of Science KAKENHI grants (grant nos. 26870163, 15H02449, and 18H03955) and by the Institute for Fermentation, Osaka (grant no. L-2018-1-006) to K.N.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
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