Effects of MAPK Homologous Genes on Chemotaxis and Egg Hatching in Meloidogyne incognita.

Root-knot nematodes, known for their broad host range and the challenges associated with their control, cause significant losses in global agricultural productivity. The mitogen-activated protein kinase (MAPK) pathway amplifies signals through a phosphorylation cascade to regulate downstream transcription factors or effector proteins, which is essential for maintaining normal physiological functions in nematodes. This study presents a comprehensive characterization of the MAPK signaling cascade regulatory network in Meloidogyne incognita, elucidating the regulatory roles of Mi-let-60, Mi-lin-45, Mi-mek-2, and Mi-mpk-1 in host chemotaxis and egg hatching behavior. Importantly, RNAi-mediated silencing of Mi-mpk-1 resulted in a 17-fold increase in egg hatching rate and significantly impaired chemotactic responses while silencing of Mi-let-60 led to a marked reduction in root gall formation and egg mass production. These results not only confirmed the evolutionary conservation of this pathway but also identified a feedback regulation mechanism unique to parasitic nematodes. These findings provide valuable insights for future research on signal transduction pathways and the sustainable management of root-knot nematodes.