Transcriptome analysis of Meloidogyne incognita during tomato parasitism in water stress conditions

Water stress and nematode parasitism are two stress sources with interacting effects in field conditions. However, few data are available on the effect of water stress on nematodes during plant parasitism. We collected tomato root segments containing galls induced by Meloidogyne incognita 7 and 14 days post inoculation (dpi) in parasitized plants, exposed or not to a water stress, to perform a comparative nematode transcriptome analysis. After filtering reads mapping on the tomato genome, the M. incognita ASM 18041v1 genome was used to identify genes up- and downregulated in M. incognita at 7 and 14 dpi, in both conditions. To assess time changes in M. incognita differentially expressed genes (DEG), RPKM cutoff values ≥ 10 were applied, between the two times course conditions. The DEGs, evaluated at 7 and 14 dpi, were considered significant when displayed at least a twofold change (Fc, p < 0.05) compared with unstressed condition. GO enrichment analyses included 93 and 703 genes up-regulated and 114 and 1093 down-regulated, at 7 and 14 dpi, respectively. Genes up-regulated at 7 dpi showed a significant enrichment of transcripts related to ion and phosphatase binding proteins along with pantothenate activity, and to several intracellular non-membrane organelle cellular components. The genes up regulated at 14 dpi showed an enrichment of transcripts related to structural constituents of cuticle and peptidase activity. The genes down-regulated at 7 dpi showed an enrichment of transcripts for different binding proteins, with glycolytic and metabolic processes, mostly down-regulated at 14 dpi. Data contribute to the understanding of M. incognita gene expression patterns, useful for the management of this nematode in arid climates and water stress conditions.