Exploring mycorrhizal function with NMR spectroscopy

Nuclear magnetic resonance (NMR) studies of mycorrhizal symbioses have illu minated a number of functional aspects of these complex associations. Here we review studies of the two main types of mycorrhiza (ectomycorrhizas and arbuscular mycorrhizas) to which NMR has been applied. Although the physiol ogical questions addressed in each case are frequently the same, these two mutualistic symbioses are sufficiently different to justify separate discus sion. In conjunction with isotopic labelling NMR is able to examine the tra nsfer of substrates between the symbionts both in vivo and in vitro, as wel l as the production of secondary metabolites in response to colonization. I n addition, this methodology is capable of determining the locations of the biosynthesis and translocations of storage compounds, such as polyphosphat es, lipids and carbohydrates, in mycorrhizal fungi both in the free-living and in the symbiotic stages of their life cycle. NMR has been useful in ana lysing metabolism, transport and energetics, and the results of such studie s have practical and ecological significance. Models of transport and physi ology to which NMR has contributed form the necessary foundation for functi onal genomic exploration. (C) New Phytologist (2001).