TY  - JOUR
AU  - Leroy, C.
AU  - Jauneau, A.
AU  - Martinez, Y.
AU  - Cabin-Flaman, A.
AU  - Gibouin, D.
AU  - Orivel, J.
AU  - Séjalon-Delmas, N.
PY  - 2017//
TI  - Exploring fungus-plant N transfer in a tripartite ant-plant-fungus mutualism
T2  - Annals of Botany
JO  - Annals of Botany
SP  - 417
EP  - 426
VL  - 120
IS  - 3
KW  - Ascomycetes
KW  - endophytic fungi
KW  - Hirtella physophora
KW  - microscopy
KW  - mutualism
KW  - myrmecophyte
KW  - NanoSIMS
KW  - stable isotope
N2  - Background and Aims The plant Hirtella physophora, the ant Allomerus decemarticulatus and a fungus, Trimmatostroma sp., form a tripartite association. The ants manipulate both the plant trichomes and the fungus to build galleries under the stems of their host plant used to capture prey. In addition to its structural role, the fungus also improves nutrient uptake by the host plant. But it still remains unclear whether the fungus plays an indirect or a direct role in transferring nutrients to the plant. This study aimed to trace the transfer of N from the fungus to the plant's stem tissue. • Methods Optical microscopy and transmission electron microscopy (TEM) were used to investigate the presence of fungal hyphae in the stem tissues. Then, a 15N-labelling experiment was combined with a nanoscale secondary-ion mass spectrometry (NanoSIMS 50) isotopic imaging approach to trace the movement of added 15N from the fungus to plant tissues. • Key Results The TEM images clearly showed hyphae inside the stem tissue in the cellular compartment. Also, fungal hyphae were seen perforating the wall of the parenchyma cell. The 15N provisioning of the fungus in the galleries resulted in significant enrichment of the 15N signature of the plant's leaves 1 d after the 15N-labelling solution was deposited on the fungus-bearing trap. Finally, NanoSIMS imaging proved that nitrogen was transferred biotrophically from the fungus to the stem tissue. • Conclusions This study provides evidence that the fungi are connected endophytically to an ant-plant system and actively transfer nitrogen from 15N-labelling solution to the plant's stem tissues. Overall, this study underlines how complex the trophic structure of ant-plant interactions is due to the presence of the fungus and provides insight into the possibly important nutritional aspects and tradeoffs involved in myrmecophyte-ant mutualisms. © The Author 2017.
UR  - http://dx.doi.org/10.1093/aob/mcx064
N1  - Export Date: 2 October 2017
ID  - Leroy_etal2017
ER  -