Parasitism by root-knot nematodes is linked to enriched nitrogen-fixing bacteria in the root microbiota. Efficient control of these parasites requires a thorough knowledge of how the root environment contributes to infestation. However, it’s unclear how root-knot nematodes interact with and affect plant root-associated microbes. To learn more, researchers recently analyzed the microbiomes in and around the roots of different types of plants with and without root-knot nematodes. They found that variations in the root-associated microbiome were due to numerous factors, including the plant species, developmental stage, and ecological function; nematode infestation status; and interactions of these factors. In tomato plants, nematode infestation was associated with higher levels of Rhizobiales and Betaproteobacteriales bacteria in roots, and the enrichment of biological pathways related to bacterial disease and nitrogen fixation, and upregulation of biological pathways related to bacterial disease and nitrogen fixation (harvesting of atmospheric nitrogen). Adding nitrogen to the soil reduced the abundance of nitrogen-fixing bacteria, the prevalence of root-knot nematodes, and the occurrence of a parasite response called galling. Although more details are needed, the findings reveal links among root-knot nematode parasitism, the root-associated microbiome, and nitrogen fixation and might provide insights to help develop new strategies for root-knot nematode control.