Abstract
BackgroundFusarium oxysporum f. sp. lycopersici (Fol) is a compendium of pathogenic and non-pathogenic fungal strains. Pathogenic strains may cause vascular wilt disease and produce considerable losses in commercial tomato plots. To gain insight into the molecular mechanisms mediating resistance to Fol in tomato, the aim of our study was to characterize the transcriptional response of three cultivars (CT1, CT2 and IAC391) to a pathogenic (Fol-pt) and a non-pathogenic (Fo-npt) strain of Fo.ResultsAll cultivars exhibited differentially expressed genes in response to each strain of the fungus at 36 h post-inoculation. For the pathogenic strain, CT1 deployed an apparent active defense response that included upregulation of WRKY transcription factors, an extracellular chitinase, and terpenoid-related genes, among others. In IAC391, differentially expressed genes included upregulated but mostly downregulated genes. Upregulated genes mapped to ethylene regulation, pathogenesis regulation and transcription regulation, while downregulated genes potentially impacted defense responses, lipid transport and metal ion binding. Finally, CT2 exhibited mostly downregulated genes upon Fol-pt infection. This included genes involved in transcription regulation, defense responses, and metal ion binding.ConclusionsResults suggest that CT1 mounts a defense response against Fol-pt. IAC391 exhibits an intermediate phenotype whereby some defense response genes are activated, and others are suppressed. Finally, the transcriptional profile in the CT2 hints towards lower levels of resistance. Fo-npt also induced transcriptional changes in all cultivars, but to a lesser extent. Results of this study will support genetic breeding programs currently underway in the zone.
Highlights
Fusarium oxysporum f. sp. lycopersici (Fol) is a compendium of pathogenic and non-pathogenic fungal strains
The plant immune system responds to pathogen attack by deploying two main defense strategies. i) recognition of pathogen-associated molecular patterns (PAMPs), such as chitin and β-glucans, by transmembrane pattern recognition receptors (PRRs), and ii) mounting a poorlyunderstood intracellular molecular defense response upon detection of plant proteins that have been activated by pathogen effectors, using polymorphic NB-LRR proteins [1]
It is important to clarify that we decided to take samples at 36 h post-inoculation because we were interested in an early defense response of tomato plants against Fol
Summary
Fusarium oxysporum f. sp. lycopersici (Fol) is a compendium of pathogenic and non-pathogenic fungal strains. NB-LRRs recognize pathogen effectors and restrict infection, triggering an amplified form of PTI, often associated with a hypersensitive response, dubbed effectortriggered immunity (ETI). Antagonistic molecular encounters between the pathogen and the plant cell ignite a cascade of transcriptional and posttranscriptional events that either result in disease or resistance and can spread systemically through the plant [4, 5]. Understanding such transcriptional responses is of paramount importance for the comprehension of disease dynamics and for the design of management strategies
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