Transcriptional alterations induced by Nacobbus aberrans in interaction with chili pepper CM-334 and Phytophthora capsici

The wilting of chili caused by Phytophthora capsici limits production of the crop. The best alternative for control of this disease is the use of crop resistance. The genotype of chili Criollo de Morelos 334 (CM-334) is resistant to P. capsici; however, its resistance is lost when it is infected by the nematode Nacobbus aberrans, a phenomenon known as breaking of resistance. With the objective of increasing knowledge about the transcriptional alterations of the defence genes associated with the resistance to the oomycete, we analyzed transcriptome in the roots of chili pepper CM-334 in response to infection by N. aberrans, by P. capsici and by the combination of both pathogens, at 12 and 24 h after inoculation with the oomycete (hpio). In plants inoculated only with P. capsici, this was detected in the neck of the plant at both of the times evaluated, whilst in plants inoculated with both pathogens, the oomycete was detected halfway up the stem at 24 hpio. Analysis of differential expression indicated that, in the plants inoculated with the oomycete, the genes PR-1b, PRB1, egl12, egl7, CPI, MIR, PGIP and CaWRKY58, could be involved in the defence of chili pepper CM-334 to P. capsici. PR-1b, CaWRKY58, CPI, MIR, HMG and PAL were modulated by N. aberrans. In addition, over-expression of gene FAD, involved in metabolism of lípids, was observed and this increase could help the nematode's requierements for fatty acids, which are essential for its development and reproduction. N. aberrans caused the transcriptional alteration of certain defence genes, which could have favoured the systemic advance of the oomycete halfway up the stem of CM-334. •When CM-334 chili pepper is infected by N. aberrans it loses resistance to P. capsici.•N. aberrans induces transcriptional alterations in defense genes of CM-334.•Suppression of defense genes favors the establishment of P. capsici in CM-334.•Overexpression of FAD gene could benefit establishment of N. aberrans in CM-334.•Induction of PGIP, MIR and IPC genes could promote resistance of CM-334 to P. capsici.