Effect of Endophytism and Parasitism on WRKYs and Defense Gene Expression in Tomato Roots.

The expression of WRKY transcription factors and plant defense-related genes was studied in the roots of Apulian tomato () cv Regina di Fasano (accessions MRT and PLZ) endophytically colonized by and parasitized or not by the root-knot nematode (RKN) . The effect on plant growth, nematode parasitism and histological aspect of the interaction were considered. The association of with RKN-parasitized MRT plants increased the total biomass and shoot fresh weight in comparison with healthy plants and with those only parasitized by RKN, without the endophyte. However, the PLZ accession showed no significant difference in the observed biometric parameters. The number of RKN-induced galls per plant was not affected by endophytism eight days after inoculation. No histological changes were observed in the nematode feeding sites in the presence of the fungus. Gene expression analysis showed an accession-specific response to with differential activation of WRKY-related genes. No significant change was found for expression in nematode-parasitized plants compared with control roots, confirming cultivar susceptibility. Data indicate genotype-specific responses of the WRKY genes to parasitism examined in roots with nematodes and/or endophytic . At 25 days post-inoculation with , no significant difference was observed in the expression of defense-related genes in both accessions, suggesting that salicylic acid (SA) ( and ) and jasmonate (JA) related genes () are not active during endophytism.