Proteomic studies of arbuscular mycorrhizal associations

SPEIPMArbuscular mycorrhizal (AM) fungi are soil-borne microorganisms forming mutualistic associations with the vast majority of land plants, including most agri- cultural relevant crops. In this association the plant provides the fungus with plant photosynthates allow- ing it to complete its life cycle, while the fungus pro- vides the plant with mineral nutrients, mainly phos- phorus and can also help the plant to tolerate biotic and abiotic stresses. In regard to these benefits there is growing interest on the use of AM fungi to improve productivity and sustainability in agricultural sys- tems. AM fungi and their interactions with plants have been extensively studied using proteomic tech- niques, but some difficulties have been faced. 1) Little is known about the AM fungal typical protein reper- toire because it is currently impossible to grow AM fungi in pure axenic cultures; 2) Plant tissues often contain high amounts of interfering substances that make protein extraction for the study of AM interac- tions a difficult procedure; 3) Most nutrient ex- changes between AM fungi and their host plants in- volve participation of membrane proteins, still poorly resolved in most separation techniques. Finally, 4) the formation of the arbuscule is an asynchronous pro- cess, making it difficult to distinguish which proteins are essential in the early or late stages of AM associa- tions. In this review we present a historical summary of how these difficulties have been overcome by tech- nological advances in proteomics and we discuss cur- rent and future trends in the study of the proteins involved in AM interactions