Hirschmanniella mucronata 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 Hirschmanniella mucronata, designated as HmENG1. In situ hybridization demonstrated the specific localization of Hmeng1 transcripts within the esophageal glands of H. mucronata. Recombinant HmENG1 exhibited cellulase activity in vitro. In planta RNAi experiments confirmed that silencing Hmeng1 significantly reduced the infection capability of H. mucronata. 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 Osgapdh knockout mutants indicated that OsGAPDH is involved in rice resistance against H. mucronata. Transcriptomic analysis suggested that the absence of OsGAPDH disrupted carbohydrate metabolism and jasmonic acid-related pathways. These findings demonstrate that HmENG1 is a classic cell wall-degrading enzyme that may exhibit multifunctional roles during H. mucronata infection of rice.