Isolation and Characterization of the Mycorrhiza Helper Bacteria from the Fairy Rings of Floccularia Luteovirens

Abstract Floccularia luteovirens is an edible ectomycorrhizal fungus which forms fairy rings (FRs) distributed on the Qinghai-Tibet Plateau. Our previous study found four isolates of potential mycorrhiza helper bacteria (MHB), but they were only isolated from a single FR and their mycorrhizal promoting ability was not tested. Thus, it was necessary to collect samples from a larger area and measure the mycorrhizal promoting ability of the potential candidates. Of 184 bacterial isolates from five fairy rings located in Qinghai-Tibet Plateau belonging to 12 species, and 7 of them (58.3%) significantly promoting the growth of F. luteovirens. We also tested the symbiosis-promoting ability of the isolates, and the results showed that only four of them stimulated the formation of mycorrhizal symbiosis . This is the first report of the construction of mycorrhizal symbiosis between F. luteovirens and its host plant in greenhouse conditions. Our results showed that the strain A89 ( Achromobacter marplatensis ) could produce antifungal properties but nonetheless stimulated the fungal growth. This may due to the nutrient condition of medium and the genotype specificity of MHBs. The results suggest that the promotion of significant growth is not a good predictor for mycorrhiza formation promotion ability of MHB.