The Non-Pathogenic Fusarium oxysporum Fo47 Induces Distinct Responses in Two Closely Related Solanaceae Plants against the Pathogen Verticillium dahliae

The non-pathogenic Fusarium oxysporum Fo47 is able to protect Capsicum annuum (pepper) but not in Solanum lycopersicum (tomato) against the pathogen Verticillium dahliae. Transcriptomics of the plant during the interaction with Fo47 shows the induction of distinct set of genes in pepper and tomato. The number of differentially expressed (DE) genes in pepper (231 DE genes) is greater than the number of DE genes in tomato (39 DE genes) at 2 days after the treatment with Fo47. Ethylene related genes were present among the DE genes in both plants, and the up-regulation of ethylene biosynthetic genes was observed to be triggered during the interaction of both plants with Fo47. The treatment with MCP (1-Methylcyclopropene, an ethylene-competitive inhibitor) reduced the Fo47 protection in pepper against Verticillium dahliae. Intriguingly, Fo47 was able to protect the ethylene-insensitive tomato mutant Never-ripe (Nr) against Verticillium dahliae, but not the tomato wilt type cv Pearson. Overall, ethylene is shown to be an important player in the response to Fo47, but its role depends on the host species.