A Conserved Root-Knot Nematode Effector Interacts with Plant Kinesin Light Chain–Related Proteins to Promote Parasitism

Root-knot nematodes (RKNs) are obligate plant parasites that establish biotrophic interactions with a wide range of host plants, causing major crop losses worldwide. During infection, RKNs secrete effector proteins from their esophageal glands into root tissues via a stylet. These effectors target specific subcellular compartments and manipulate host cell functions to induce the formation of hypertrophied and multinucleated giant cells, which serve as feeding sites essential for nematode development. Here, we describe a new RKN-specific effector, EFFECTOR17 (EFF17), conserved in the five most damaging RKN species: Meloidogyne incognita , M. enterolobii , M. arenaria , M. javanica , and M. hapla . In situ hybridization showed that EFF17 genes are specifically expressed in the esophageal glands of various RKN species. Silencing EFF17 in M . incognita reduced its reproduction on Nicotiana benthamiana , supporting a contribution to parasitism. Yeast two-hybrid and split luciferase assays revealed that MiEFF17 interacts with tomato and Arabidopsis KINESIN LIGHT CHAIN RELATED (KLCR)/CELLULOSE-MICROTUBULE UNCOUPLING (CMU) proteins. Arabidopsis klcr mutants developed significantly fewer egg masses. Our findings propose that EFF17 manipulates KLCR function to promote parasitism. Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .