Differential Extent of Vascular Invasion by Fusarium oxysporum f. sp. Lycopersici on Infection of Domesticated and Wild Tomatoes (Solanum spp.)

Presenter: Isabelle Sophia Miranda Schramm von Blucher

Faculty Sponsor: Ana Caicedo

School: UMass Amherst

Research Area: Biological Organisms

Session: Poster Session 6, 4:15 PM - 5:00 PM, Auditorium, A53

ABSTRACT

Fusarium oxysporum f. sp. Lycopersici (FOL), a persistent fungal pathogen, infects domesticated tomatoes (Solanum lycopersicum L. var. lycopersicum), which are a major global crop. In an evolutionary arms race, humans have introgressed alleles conferring resistance to certain FOL strains from wild tomato species into cultivated tomatoes. In turn, FOL has repeatedly evolved new mechanisms of virulence. Given this pattern, we expect FOL to evolve new mechanisms of virulence, overcoming current resistance in crops. To find novel resistance alleles for introgression into domesticated tomatoes, we quantified the response to FOL infection in 226 accessions of domesticated tomatoes, along with their semi-domesticated (Solanum lycopersicum cerasiforme) and wild (Solanum pimpinellifolium) relatives. Using a disease index based on wilting severity, we selected the five most and five least resistant accessions for further analysis. We used qPCR to measure fungal DNA levels relative to plant DNA in the bottom 2 centimeters of host stems after FOL inoculation. We found consistently low relative fungal DNA in resistant successions, while susceptible accessions exhibited a wide range of fungal DNA levels. This suggests that disease progression can occur even with minimal fungal presence in the stem, and invasion may take varying amounts of time depending on the host accession. Our next step is to visualize fungal invasion using confocal microscopy, focusing on differences in the extent of fungal invasion in the roots of resistant and susceptible host tomato plants.

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