**Fungi–Nematode Interactions: Diversity, Ecology, and Biocontrol Prospects in Agriculture**

**Ying Zhang 1, Shuoshuo Li 1,2, Haixia Li 1,2, Ruirui Wang 1,2, Ke-Qin Zhang 1,\* and Jianping Xu 1,3,\***


Received: 15 September 2020; Accepted: 2 October 2020; Published: 4 October 2020

**Abstract:** Fungi and nematodes are among the most abundant organisms in soil habitats. They provide essential ecosystem services and play crucial roles for maintaining the stability of food-webs and for facilitating nutrient cycling. As two of the very abundant groups of organisms, fungi and nematodes interact with each other in multiple ways. Here in this review, we provide a broad framework of interactions between fungi and nematodes with an emphasis on those that impact crops and agriculture ecosystems. We describe the diversity and evolution of fungi that closely interact with nematodes, including food fungi for nematodes as well as fungi that feed on nematodes. Among the nematophagous fungi, those that produce specialized nematode-trapping devices are especially interesting, and a grea<sup>t</sup> deal is known about their diversity, evolution, and molecular mechanisms of interactions with nematodes. Some of the fungi and nematodes are significant pathogens and pests to crops. We summarize the ecological and molecular mechanisms identified so far that impact, either directly or indirectly, the interactions among phytopathogenic fungi, phytopathogenic nematodes, and crop plants. The potential applications of our understanding to controlling phytophagous nematodes and soilborne fungal pathogens in agricultural fields are discussed.

**Keywords:** nematophagous fungi; cross-kingdom interactions; food-web cycling; phytophagous nematodes; soilborne fungal pathogens
