Fungal functional guilds, especially plant pathogens and mycorrhizal fungi are critical to ecosystem functioning and the maintenance of species diversity in terrestrial ecosystems. The importance of pathogens has gained considerably empirical support in regulating species abundance in tropical and subtropical forests by inducing negative density dependence. Also, plant species may become locally dominant because they can take up both organic and inorganic nitrogen in soil by forming root symbioses with mycorrhizal fungi. However, a comprehensive study of how theses fungal guilds are related to their host abundance and how they are interacted in a framework of network is still lacking. Here, we collected 529 root tip samples from 45 plant species which cover a wide range of relative abundance and phylogenetic relatedness in a subtropical forest in southern China. The fungal communities in root tips were assessed by MiSeq pyrosequencing and the taxa were assigned to two major guilds including plant pathogens and mycorrhizal fungi. We found that the plant-fungus network showed different levels of multiple network indices, which illustrated an architecturally diverse ecological network in our system. Collectively, our work highlights the profound importance of belowground fungal functional guilds in regulating the diversity and composition of aboveground plant communities.