| Summary: | The root-knot nematode (<i>Meloidogyne incognita</i>) causes huge economic losses in the agricultural industry throughout the world. Control methods against these polyphagous plant endoparasites are sparse, the preferred one being the deployment of plant cultivars or rootstocks bearing resistance genes against <i>Meloidogyne</i> species. Our previous study has cloned one resistance gene, <i>PsoRPM3</i>, from Xinjiang wild myrobalan plum (<i>Prunus sogdiana</i>). However, the function of <i>PsoRPM3</i> remains elusive. In the present study, we have investigated the regulatory mechanism of <i>PsoRPM3</i> in plant defense responses to <i>M. incognita</i>. Our results indicate that fewer giant cells were detected in the roots of the <i>PsoRPM3</i> transgenic tobacco than wild tobacco lines after incubation with <i>M. incognita</i>. Transient transformations of full-length and TN structural domains of <i>PsoRPM3</i> have induced significant hypersensitive responses (HR), suggesting that TIR domain might be the one which caused HR. Further, yeast two-hybrid results revealed that the full-length and LRR domain of <i>PsoRPM3</i> could interact with the transcription factor <i>Pso9TF</i>. The addition of <i>Pso9TF</i> increased the ROS levels and induced HR. Thus, our data revealed that the LRR structural domain of <i>PsoRPM3</i> may be associated with signal transduction. Moreover, we did not find any relative inductions of defense-related genes <i>PsoEDS1</i>, <i>PsoPAD4</i> and <i>PsoSAG101</i> in <i>P. sogdiana</i>, which has been incubated with <i>M. incognita</i>. In summary, our work has shown the key functional domain of <i>PsoRPM3</i> in the regulation of defense responses to <i>M. incognita</i> in <i>P. sogdiana</i>.
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