Molecular tools for tracing arbuscular mycorrhizal fungi (AMF) andplant growth-promoting rhizobacteria (PGPR)

A next-generation green revolution towards a more sustainable, low-input but still highly productive agriculture is urgently needed. A key for this is below-ground: The intricate interplay of plant roots with the soil microbiota is crucial for natural soil fertility and, thus, for any sound agro-ecosystem. To harness this below-ground potential and to apply it in agriculture, the ISCB-Biofertilizer network, a consortium of Indian and Swiss research groups, tries to develop a biofertilizer based on the two most important symbiotic soil microbes, namely the arbuscular mycorrhizal fungi (AMF) and the plant growthpromoting rhizobacteria (PGPR). Recently we have shown that combined application of AMF and PGPR improves the yield and quality of wheat in marginal farms of India. An important aspect for developing the formulation of AMF and PGPR to a successful biofertilizer is the ability to trace the microbial strains involved, ideally with the help of unique, DNA-based diagnostic tools. This does not only help to establish the survival of the applied microbes in field condition but also to validate its persistence over time.