Cloning arbuscule-related genes from mycorrhizas

Until recently little was known about the identity of the genes expressed in the arbuscules of mycorrhizas, due in part to problems associated with cloning genes from the tissues of an obligate symbiont. However, the combination of advanced molecular techniques, innovative use of the materials available and fortuitous cloning has resulted in the recent identification of a number of arbuscule-related genes. This article provides a brief summary of the genes involved in arbuscule development, function and regulation, and the techniques used to study them. Molecular techniques include differential screening, differential display and screening with heterologous probes, and can involve the use of mycorrhizal plant mutants. New technologies such as proteome analysis are also discussed.