A procedure for the establishment of Glomus mosseae in dual culture with Ri T-DNA-transformed carrot roots

A stepwise procedure was investigated to determine the optimal conditions for the establishment of Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe in dual in vitro culture with Ri T-DNA-transformed roots of Daucus carota L. Glomus mosseae spores germinated best in 10 mM Tris or MES-buffered medium at pH values just above neutral. Growth of hyphae from germinated spores was much greater in the presence of Tris than MES, eg. 8 mm versus 4 mm per spore for Tris and MES, respectively, at pH 7.2. Roots exhibited a broad pH optimum for growth of 6.0-7.0 in both MES and Tris, but did not grow well above pH 7.5. In addition, purified gelling agent, gellan gum, was utilized to lower the P concentration of media. With these factors combined, mycorrhizas were successfully established in 14% of dual cultures.