Transcriptome analysis of Meloidogyne incognita encumbered by Pasteuria penetrans endospores provides new insights into bacteria and nematode interaction

Root-knot nematodes (RKN, Meloidogyne spp.) are one of the most harmful pests in agriculture. Pasteuria penetrans , an obligate hyperparasite of RKN, is an effective biological control agent. However, little is known about the molecular mechanisms of interaction between P. penetrans and the second-stage juvenile (J2) of Meloidogyne incognita . Here, we used transcriptome sequencing to characterise the differential expression profiles between control J2 of M. incognita and J2 encumbered by P. penetrans endospores. A total of 445 genes were found to be differentially expressed, including 406 up-regulated and 39 down-regulated genes. Thirty-seven putative immune-related genes encoding collagens, cytochrome P450, lysozymes and other active proteins were identified. Genes involved in the ‘biosynthesis of unsaturated fatty acids’ pathway and several core sets of immune effectors were up-regulated, indicating conserved immune mechanisms among different nematodes. Down-regulation of cytochrome P450-related genes might suggest a specific defence response of M. incognita encumbered by P. penetrans endospores.