Variable carbon-sink strength of different Glomus mosseae strains colonizing barley roots

Root carbon (C) partitioning was investigated in barley (Hordeum vulgare L.) colonized by one of three strains of the arbuscular mycorrhizal fungus (AMF) Glomus mosseae (Nicolson & Gerdemann) Gerd. & Trappe. The roots of each plant were evenly divided between two compartments of a split-root system and one side was inoculated with one of the three AMF strains. Twenty-three days after inoculation barley shoots were labeled with 14CO2. Twenty-four hours later, plants were harvested and the mycorrhizal (M) and nonmycorrhizal (NM) roots were analyzed separately for 14C. Partitioning of C between M and NM sides differed between the fungal strains: BEG 54 was a strong C sink, BEG 55 was a moderately strong C sink, and BEG 12 showed similar C-sink strength as the non-inoculated control plants. The observed differences in C-sink strength mirrored differences in plant dry biomass. Total plant dry biomass of plants inoculated with BEG 12, BEG54, and BEG 55 represented 81.3%, 65.3%, and 73.4% of the biomass of the control plants, respectively. This paper is the first report of an AMF strain-specific variation of C partitioning in M plants in a split-root system.