Arbuscular mycorrhizal fungus causes increased condensed tannins concentrations in shoots but decreased in roots of Lotus japonicus L.

Condensed tannins are a class of plant secondary metabolites which are formed by the condensation of flavanols, and play an important role in plant-soil-microbes interactions by influencing the colonisation of arbuscular
mycorrhizal (AM) fungi. The aim of this study was to determine the influence of AM fungi on condensed tannins concentrations in roots, stems and leaves of birdsfoot trefoil (Lotus japonicus L.). The concentrations of condensed
tannins in roots, stems and leaves of the Lotus japonicus plants were measured using histochemical staining and spectrophotometry. The extent of AM fungal colonisation in roots was also quantified. Soluble and insoluble condensed tannins concentrations in roots were lower in plants inoculated with AM fungi but higher in stems and leaves compared to plants not inoculated with AM fungi. The higher concentration of condensed tannins in the stems and leaves were associated with AM fungi colonisation of roots. This had increased animal feed value and also could be influenced by the plant-soil-microbes feedback processes.