A legume erases mycorrhizal negative effects on an endophytic grass increasing N transference

GARCIA PARISI, PA; OMACINI, M; GRIMOLDI, AA; LATTANZI, FA

Praga

Congreso; 9th International Conference on Mycorrhiza; 2017

International Mycorrhiza Society

Plant coexistence can be affected by the interaction of multiple plant symbionts. The outcome of co-infection with arbuscular mycorrhizal fungi (AMF) and foliar endophytic fungi (FEF) in grasses is variable and may range from antagonism to synergism. Here we tested whether a nitrogen-fixing legume affects grass response to the presence of both types of symbionts by enhancing N nutrition. The grass (Lolium multiflorum), either associated or not with FEF (Epichloë occultans), grew in monocultures or in mixtures with legumes (Trifolium repens inoculated with rhizobia) in pots with sterilized soil. In half of the pots, we added AMF inoculum (Simiglomus hoi, Funneliformis mosseae, Rhizophagus irregularis). We measured plant biomass and the transference of atmospheric-N fixed from the legume to the grass. Legume biomass and the amount of N fixed were affected neither by AMF inoculation nor by FEF presence in the neighboring grass. In mixtures, AMF inoculation increased more than three times the amount of N-fixed transferred to both the FEF-associated and the FEF-free grass, but increased 26% the biomass of only the FEF-free grass. In monocultures, it reduced 18% grass biomass irrespective of FEF presence.The presence of nitrogen-fixing plant erases the parasitic effect of AMF on a grass by enhancing the transference of fixed N, but this emergent property was not enough to be positive for FEF-associated grass plants. In conclusion, biotic context can influence the outcome of the co-infection with two types of symbionts and thus the level of antagonism between AMF and FEF within the grass.