Transcriptomic changes in the pre-parasitic juveniles of Meloidogyne incognitainduced by silencing of effectors Mi-msp-1and Mi-msp-20

Plant–parasitic root-knot nematode Meloidogyne incognitauses an array of effector proteins to establish successful plant infections. Mi-msp-1and Mi-msp-20are two known effectors secreted from nematode subventral oesophageal glands; Mi-msp-1being a putative secretory venom allergen AG5-like protein, whereas Mi-msp-20is a pioneer gene with a coiled-coil motif. Expression of specific effector is known to cause disturbances in the expression of other effectors. Here, we used RNA-Seq to investigate the pleiotropic effects of silencing Mi-msp-1and Mi-msp-20. A total of 25.1–51.9 million HQ reads generated from Mi-msp-1and Mi-msp-20silenced second-stage juveniles (J2s) along with freshly hatched J2s were mapped to an already annotated M. incognitaproteome to understand the impact on various nematode pathways. As compared to control, silencing of Mi-msp-1caused differential expression of 29 transcripts, while Mi-msp-20silencing resulted in differential expression of a broader set of 409 transcripts. In the Mi-msp-1silenced J2s, cytoplasm (GO:0005737) was the most enriched gene ontology (GO) term, whereas in the Mi-msp-20silenced worms, embryo development (GO:0009792), reproduction (GO:0000003) and nematode larval development (GO:0002119) were the most enriched terms. Limited crosstalk was observed between these two effectors as a sheer 5.9% of the up-regulated transcripts were common between Mi-msp-1and Mi-msp-20silenced nematodes. Our results suggest that in addition to the direct knock-down caused by silencing of Mi-msp-1and Mi-msp-20, the cascading effect on other genes might also be contributing to a reduction in nematode's parasitic abilities.