Stimulation of hyphal growth of the VA mycorrhizal fungus Gigaspora margarita by suspension‐cultured Pueraria phaseoloides cells and cell products

summary The effects of suspension-cultured Pueraria phaseoloides Benth. (pueraria) cells and cell products on growth of hyphae of the VA mycorrhizal fungus Gigaspora margarita Becker & Hall in liquid media were examined. Addition of 6-d-old cell cultures of pueraria cells at a concentration of 25 cells ml−1 of medium caused a 3.9-fold increase in hyphal growth. Higher cell concentrations resulted in less growth stimulation. Cell exudates or extracts (cell products) at a concentration of 25 μl−1 of medium also stimulated hyphal growth. Successive cell additions, or transfer of the spores into fresh media containing pueraria cells, resulted in no additional hyphal growth. Spores soaked in exudates or extracts showed faster and more vigorous growth when plated on an agar medium than those soaked in a control solution. It is suggested that suspension-cultured pueraria cells stimulate hyphal growth of VA mycorrhizal fungi by accumulating and leaking very active metabolites into the medium.