Effects of plant species identity and foliar herbivory on root morphological traits and arbuscular mycorrhizal fungal symbiosis

Abstract Foliar herbivory can influence plant resource allocation and belowground interactions, but its effects on root morphological traits and associated soil microbial communities remain poorly understood. In particular, although foliar herbivory has been shown to influence arbuscular mycorrhizal fungi (AMF) colonization rate, its effects on AMF community composition, diversity, and co-occurrence network stability are less well characterized. Using seven Asteraceae species and a generalist herbivore, we examined how plant species identity and foliar herbivory influence root morphological traits and AMF symbiosis. We found that plant species differed significantly in root traits, AMF colonization, and AMF community composition. Across species, foliar herbivory increased specific root length and specific root surface area, while reducing root diameter. Herbivory also decreased AMF colonization, overall AMF alpha diversity, as well as the negative cohesion and modularity of AMF co-occurrence networks. In addition, herbivory had contrasting effects on abundant and rare AMF taxa: it altered the composition of rare taxa while reducing the alpha diversity of abundant taxa. Together, our findings provide empirical evidence that foliar herbivory modifies root traits and restructures rhizosphere AMF communities, and this study proposes a new framework to explore the complex tripartite interactions among insects, host plants, and AMF symbiosis.