Some studies relating to "independent" growth of vesicular–arbuscular endophytes

Abstract

In dual culture with Ri T-DNA transformed carrot roots nutrient conditions were sought that would totally suppress mycorrhizal infection while stimulating "independent" growth of vesicular–arbuscular endophytes. In this system fungal development in the agar was comparable in extent with that normally occurring only after mycorrhizal infection has become well established; it differed qualitatively from that characteristic of germinating spores and extramatrical mycelium in such cultures. There was profuse development of arbuscule-like branches, many anastomoses, and increased branching of extension hyphae. Biomass increased up to fivefold when the mycelium was detached in situ from the inoculum (root pieces or spores). Growth from explants was little more than residual and was hampered by extensive bacterial contamination at the desired pH, near neutrality. The rationale of this approach to the culture of vesicular–arbuscular endophytes is discussed.