Interactions between arbuscular mycorrhizal fungi and non-host Carex capillacea.

A topic of confusion over the interactions between arbuscular mycorrhizal (AM) fungi and plants is the mycorrhizal status of some plant families such as Cyperaceae, which is generally considered to be non-mycorrhizal. Here, we conducted experiments to explore how the abiotic environmental conditions and AM network influence the interactions between AM fungi and Carex capillacea. We grew Carex capillacea alone or together with a mycorrhizal host species Medicago sativa in the presence or absence of AM fungi (soil inoculum from Mount Segrila and Rhizophagus intraradices from the Chinese Bank of the Glomeromycota, BGC). Plants were grown in a growth chamber and at two elevational sites of Mount Segrila, respectively. The results indicate that mycorrhizal host plants ensured the presence of an active AM fungal network whether under growth chamber or alpine conditions. The AM fungal network significantly depressed the growth of C. capillacea, especially when native inocula were used and the plants grew under alpine site conditions, although root colonization of C. capillacea increased in most cases. Moreover, the colonization level of C. capillacea was much higher (≤ 30%) when growing under alpine conditions compared with growth chamber conditions (< 8.5%). Up to 20% root colonization by Rhizophagus intraradices was observed in monocultures under alpine conditions. A significant negative relationship was found between shoot phosphorus concentrations in M. sativa and shoot dry mass of C. capillacea. These results indicate that growing conditions, AM network, and inoculum source are all important factors affecting the susceptibility of C. capillacea to AM fungi, and growing conditions might be a key driver of the interactions between AM fungi and C. capillacea.

The Interactions between Arbuscular Mycorrhizal Fungi and Trichoderma longibrachiatum Enhance Maize Growth and Modulate Root Metabolome under Increasing Soil Salinity.

Trichoderma longibrachiatum sp. are free-living filamentous fungi which are common in agro-ecosystems. However, few studies thus far have examined the interaction between Trichoderma longibrachiatum and arbuscular mycorrhizal (AM) fungi in saline soil and their potential for improving plant stress tolerance. Here, single, dual-inoculated (T. longibrachiatum MF, AM fungal community or Glomus sp.), and non-inoculated maize (Zea may L.) were subjected to different salinity levels (0, 75, 150, and 225 mM NaCl) to test the synergistic effects of dual inoculants on maize plants in different salt stress conditions. Plant performance and metabolic profiles were compared to find the molecular mechanisms underlying plant protection against salt stress. The first experiment revealed that dual inoculation of an AM fungal community and T. longibrachiatum MF improved the biomass and K+/Na+ ratio in maize under non-saline conditions, and generally enhanced AM fungal growth in root and soil under all but the 225 mM NaCl conditions. However, MF inoculant did not influence the structure of AM fungal communities in maize roots. In the second experiment, dual inoculation of Glomus sp. and T. longibrachiatum MF increased maize plant biomass, K+/Na+ ratio, and AM fungal growth in root and soil significantly at both 0 and 75 mM NaCl conditions. We identified metabolic compounds differentially accumulated in dual-inoculated maize that may underline their enhanced maize plant tolerance to increasing soil salinity. Our data suggested that the combination of Glomus sp. and T. longibrachiatum leads to interactions, which may play a potential role in alleviating the stress and improve crop productivity in salt-affected soils.