Analyses of the root-knot nematode (Meloidogyne graminicola) transcriptome during host infection highlight specific gene expression profiling in resistant rice plants

The plant-parasitic nematodeMeloidogyne graminicolacauses considerable damages to rice (Oryza sativa) culture. Resistance toM. graminicolain the related speciesOryza glaberrimareduces root penetration by juveniles and stops further nematode development.M. graminicolagenes expressed duringO. sativainfection were previously characterized but no information is available about the molecular dialogue established with a resistant plant. We compared theM. graminicolatranscriptomes of stage-two juveniles (J2s) before and during infection of susceptible or resistant rice. Among 36,121M. graminicolagenes surveyed, 367 were differentially expressed during infection of resistant or susceptible plants. Genes encoding cell wall-degrading enzymes, peptidases and neuropeptides were expressed for a longer time in resistant plants compared to susceptible plants. Conversely, genes related to nematode development were not activated in the resistant host. The majority ofM. graminicolaeffector genes had similar expression patterns, whatever the host genotype. However, two venom allergen-like protein (VAP)-encoding genes were specifically induced in resistant plants andMg-VAP1silencing in J2s reduced their ability to colonize roots. This study highlighted thatM. graminicolaadapts its gene expression to the host susceptibility. Further investigation is required to assess the role ofMg-VAPsin the rice-nematode interaction