Proteomics unravels new candidate genes for Meloidogyne resistance in wild Arachis

Arachis stenosperma is a wild peanut relative exclusive to South America that harbors high levels of resistance against several pathogens, including the peanut root-knot nematode (RKN) Meloidogyne arenaria. In this study, a proteomic survey of A. stenosperma-M. arenaria interaction using 2-DE and LC-MS/MS identified approximately 1400 proteins, out of which 222 were differentially abundant (DAPs) when RKN inoculated root samples were compared to the control. Most of these DAPs were assigned to functional categories related to plant responses to pathogens including stress, glycolysis, redox and tricarboxylic acid cycle. The comparison between the transcriptome (RNA-Seq) and proteome expression changes, showed that almost 55% of these DAPs encode genes with a similar expression trend to their protein counterparts. Most of these genes were induced during RKN infection and some were related to plant defense, such as MLP-like protein 34 (MLP34), cinnamoyl-CoA reductase 1 (CCR1), enolase (ENO), alcohol dehydrogenase (ADH) and eukaryotic translation initiation factor 5A (eIF5A). The overexpression of AsMLP34 in Agrobacterium rhizogenes transgenic roots in a susceptible peanut cultivar showed a reduction in the number of M. arenaria galls and egg masses, indicating that AsMLP34 is a promising candidate gene to be exploited in breeding programs for RKN control in peanut. SIGNIFICANCE: The use of an integrated approach to compare plant-nematode transcriptional and translational data enabled the identification of a new gene, AsMLP34, for Meloidogyne resistance.