<i>Hirschmanniella mucronata</i> Effector HmENG1 Interacts with OsGAPDH to Promote Nematode Infection in Rice

β-1,4-endoglucanase (ENG) is a canonical effector protein secreted by the esophageal glands of plant-parasitic nematodes. Homology analysis identified a β-1,4-endoglucanase homolog in <i>Hirschmanniella mucronata</i>, designated as HmENG1. In situ hybridization demonstrated the specific localization of <i>Hmeng1</i> transcripts within the esophageal glands of <i>H. mucronata</i>. Recombinant HmENG1 exhibited cellulase activity in vitro. In planta RNAi experiments confirmed that silencing Hmeng1 significantly reduced the infection capability of <i>H. mucronata</i>. In addition to its potential role in degrading plant cell walls, HmENG1 was found to interact with glyceraldehyde-3-phosphate dehydrogenase (OsGAPDH) in yeast and plant systems. Furthermore, analysis of <i>Osgapdh</i> knockout mutants indicated that OsGAPDH is involved in rice resistance against <i>H. mucronata</i>. Transcriptomic analysis suggested that the absence of OsGAPDH disrupted carbohydrate metabolism and jasmonic acid-related pathways. These findings demonstrated that HmENG1 is a classic cell wall-degrading enzyme that may exhibit multifunctional roles during <i>H. mucronata</i> infection of rice.