VBA-AMF: A VBA Program Based on the Magnified Intersections Method for Quantitative Recording of Root Colonization by Arbuscular Mycorrhizal Fungi

The extent of mycorrhizal fungi colonization is an important factor for determining the function of mycorrhizal fungi in fungi-host interaction, and quantifying the extent of mycorrhizal fungi colonization is a fundamental and essential task for researchers engaged in mycorrhizal studies. Intersect methods, such as the gridline intersect and magnified intersections methods, are accurate and objective, and are widely used to assess the colonization status of arbuscular mycorrhizal (AM) fungus. However, no convenient procedures or add-ins for Excel spreadsheets have been developed to simplify these methods. Here, we propose a procedure using the Visual Basic for Application (VBA) program in Excel that is based on the magnified intersections method, which we refer to as VBA-AMF (arbuscular mycorrhizal fungi). Time-saving and convenience are the two most prominent advantages of the VBA-AMF procedure, as it enables researchers to compute the colonization rate of AM fungi in roots, and consequently the extent of root colonization by AM fungi. VBA-AMF can also be modified to measure the status of other fungal colonizations in plant roots following the same strategy.