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

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

Gladiolus production in soil-less culture and the impact of Trichoderma harzianum and Aneurinobacillus migulanus as biological control agents

Trichoderma harzianum and Aneurinobacillus migulanus were tested separately and in combination as potential biological control agents against F. oxysporum f. sp. gladioli on gladiolus in soil-less culture.  The major secondary metabolites produced by Trichoderma harzianum against F. oxysporum f. sp. gladioli in the treated gladiolus corms as well as in the potato dextrose broth were studied.  The impact of re-application times on the effectiveness of Trichoderma harzianum and Aneurinobacillus migulanus against gladiolus corm rot and Gladiolus production in soil-less culture was examined. Results showed that T. harzianum proved to use different mechanisms against F. oxysporum f. sp. gladioli depending on  the inoculation method. T. harzianum and A. migulanus reduced host defence enzymes.  Also, they increased GA 3 and IAA content in the corms.  SEM showed that the suppressive mechanisms of T. harzianum and A. migulanus differed T. harzianum appeared to operate through a combination of antibiosis and substrate competition, 6-n-pentyl-6H-pyran-2-one (6PP) and harzianic acid (HA) were found as the main metabolites secreted by T. harzianum.  A significant positive correlation was revealed between qPCR and CFU for both T. harzianum and F. oxysporum f. sp. gladioli.  Multiple applications of T. harzianum and A. migulanus re- application was a successful strategy for suppression of F. oxysporum f. sp. gladioli.  Briefly, T. harzianum was more effective than A. migulanus in F. oxysporum f. sp. gladioli suppression and Gladiolus growth enhancement in soil-less culture. The mixing strategy between T. harzianum and A. migulanus failed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo