RocTest: A standardized method to assess the performance of root organ cultures in the propagation of arbuscular mycorrhizal fungi.

Over the past three decades, root organ cultures (ROCs) have been the gold standard method for studying arbuscular mycorrhizal fungi (AMF) under conditions, and ROCs derived from various plant species have been used as hosts for AM monoxenic cultures. While there is compelling evidence that host identity can significantly modify AMF fitness, there is currently no standardized methodology to assess the performance of ROCs in the propagation of their fungal symbionts. We describe , a robust methodological approach that models the propagation of AMF in symbiosis with ROCs. The development of extraradical fungal structures and the pattern of sporulation are modeled using cumulative link mixed models and linear mixed models. We demonstrate functionality of by evaluating the performance of three species of ROCs (, , in the propagation of three species of AMF (, , sp.). produces a simple graphical output to assess the performance of ROCs and shows that fungal propagation depends on the three-way interaction between ROC, AMF, and time. makes it possible to identify the best combination of host/AMF for fungal development and spore production, making it an important asset for germplasm collections and AMF research.