An Method for Studying the Three-Way Interaction between Soybean, and the Soil-Borne Pathogen .

In this work, we described an system adequate for investigating the pathosystem soybean/arbuscular mycorrhizal fungi (AMF)/ Pre-mycorrhized plantlets with were infected by either locally via a plug of gel supporting mycelium (Method 1) or via a macroconidia suspension applied to the medium surface (Method 2). Root colonization by the AMF and infection by the pathogen were similar to the usual observations in pot experiments. Within a period of 18 days, more than 20% of the roots were colonized by the AMF and infection by the pathogen was observed in all the plants. In presence of AMF, a decrease in symptoms and in the level of root tissue infection was noticed. With Method 1, smaller necrotic lesions were observed in the pre-mycorrhized plantlets. In Method 2, pathogen infection was slower but more homogenous. These results demonstrated the suitability of the cultivation system to study the pathosystem soybean/AMF/. We propose this cultivation system for studying the mechanisms involved in the biocontrol conferred by AMF against in soybean.