Fusarium proliferatum isolated from garlic in Spain: Identification, toxigenic potential and pathogenicity on related Allium species

Resumen

Fusarium proliferatum has been reported on garlic in the Northwest USA, Spain and Serbia, causing
water-soaked tan-colored lesions on cloves. In this work, Fusarium proliferatum was isolated from 300 symptomatic
garlic bulbs. Morphological identification of Fusarium was confirmed using species-specific PCR assays and EF-1α
sequencing. Confirmation of pathogenicity was conducted with eighteen isolates. Six randomly selected F. proliferatum
isolates from garlic were tested for specific pathogenicity and screened for fusaric acid production. Additionally,
pathogenicity of each F. proliferatum isolate was tested on healthy seedlings of onion (Allium cepa), leek (A.
porrum), scallions (A. fistulosum), chives (A. schoenoprasum) and garlic (A. sativum). A disease severity index (DSI)
was calculated as the mean severity on three plants of each species with four test replicates. Symptoms on onion
and garlic plants were observed three weeks after inoculation. All isolates tested produced symptoms on all varieties
inoculated. Inoculation of F. proliferatum isolates from diseased garlic onto other Allium species provided new
information on host range and pathogenicity. The results demonstrated differences in susceptibility with respect
to host species and cultivar. The F. proliferatum isolates tested all produced fusaric acid (FA); correlations between
FA production and isolate pathogenicity are discussed. Additionally, all isolates showed the presence of the FUM1
gene suggesting the ability of Spanish isolates to produce fumonisins.