Capsicum annuum L. CM334 is susceptible to Nacobbus aberrans but highly resistant to Phy-tophthora capsici. Resistance to P. capsici is associated with the over-expression of various defense genes such as those encoding pathogenesis-related proteins. The transcriptional alterations of defense-related genes were determined in galls induced by N. aberrans (Na) in CM334 chili roots. Transcripts accumulation of WRKY-a, WRKY1, POX (peroxidase), PR-1 (pathogenesis-related protein 1), and EAS (5-epiaristolochene synthase) was estimated by qRT-PCR, and they were compared with those recorded in the incompatible CM334- P. capsici (Pc) interaction. The levels of all studied genes were significantly (P s 0.05) lower (WRKY1, POX and PR-1) or down-regulated (WRKY-a and EAS) in the presence of N. aberrans; in contrast, in the incompatible interaction, all genes were significantly up-regulated. The alterations induced by N. aberrans could be necessary to ensure the successful completion of its life cycle in CM334 chili roots.
