Carbon partitioning in a split-root system of arbuscular mycorrhizal plants is fungal and plant species dependent

Root carbon (C) partitioning in two host plant species colonized by one of three arbuscular mycorrhizal (AM) fungal species was investigated. Split-root systems of barley (Hordeum vulgare) and sugar maple (Acer saccharum) were inoculated on one side with one of three AM fungi. Leaves were labelled with (CO2)-C-14 3 wk after inoculation. Plants were harvested 24 h later and the root systems from the mycorrhizal (M) and nonmycorrhizal (NM) sides were analysed separately for C-14. Partitioning of C-14 between M and NM sides varied depending on the fungal and host plant species used. Gigaspora rosea showed a strong C-sink capacity with both plant species, Glomus intraradices showed a strong C-sink capacity with barley, and Glomus mosseae did not affect C-14 partitioning. The C-sink strength of the M barley roots inoculated with G. rosea or G. intraradices was linearly correlated with the degree of colonization. The use of three AM fungal and two plant species allowed us to conclude that C-sink strength of AM fungi depends on both partners involved in the symbiosis.