Figure 3.

Guidelines for phenotyping arbuscular mycorrhizal (AM) symbiosis. AM phenotyping data should contain three essential features. Visual diagnosis includes AM fungal staining to quantify the colonization level and assess shapes of AM fungal structures. Stage‐specific host and fungal molecular marker gene expression should support the visual observations. Root samples should be harvested at least at two‐time points to capture the early and late stages of AM fungal colonization. This initial evaluation will reveal a specific stage when a plant host gene is likely to function. We listed assays that may help to address roles of host genes in each stage of AM fungal colonization.