Abstract
In 2022, an outbreak of apparent Fusarium wilt raised concern because the disease has historically been sporadic and infrequent. Previous studies reported that the primary causal agent of this disease in the United States is Fusarium oxysporum f. sp. nicotianae, but the identity of other Fusarium spp. responsible for Fusarium wilt and root rot and their pathogenicity have not been thoroughly investigated. To identify Fusarium species associated with the recent disease outbreak in flue-cured tobacco, 36 symptomatic plants with apparent one-sided wilting were sampled from 14 fields in Virginia and North Carolina. Forty-seven obtained isolates showed colony morphology typical of Fusarium spp. on potato dextrose agar (PDA) medium. Fifteen isolates representing colony variations on PDA were further selected for microscopic examination and molecular identification using the translation elongation factor 1-alpha (tef1-α) gene. Phylogenetic analysis of tef1-α nucleotide sequences identified nine Fusarium species representing five distinct species complexes: Fusarium incarnatum-equiseti (six isolates), F. oxysporum (three isolates), F. solani (three isolates), F. fujikuroi (two isolates), and F. tricinctum (one isolate). The pathogenicity of each isolate was assessed on flue-cured tobacco cultivar K326 seedlings at the six-leaf stage in greenhouse inoculation experiments with or without wounding. All 15 Fusarium isolates were pathogenic, causing root rot, leaf necrosis, and reduced growth parameters compared with the control treatment. The diversity of Fusarium species associated with Fusarium wilt of tobacco and the variability in aggressiveness among Fusarium species within the same species complex or belonging to different Fusarium species complexes provide a theoretical basis for future research on the epidemiology of Fusarium disease in tobacco and integrated disease management strategies to reduce disease development and severity.
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Claims 4
Claim · model-written summary
Nine Fusarium species in five species complexes were identified from flue-cured tobacco with Fusarium wilt.
FusariumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“To identify Fusarium species associated with the recent disease outbreak in flue-cured tobacco”
e1“identified nine Fusarium species representing five distinct species complexes”
Claim · model-written summary
All 15 Fusarium isolates were pathogenic on flue-cured tobacco cultivar K326 seedlings in greenhouse inoculation experiments, causing root rot and leaf necrosis.
- Taxon
- flue-cured tobaccoe2
- Material
- cultivar K326e2
- Organ / stage
- six-leaf stagee2
- Treatment
- inoculation experiments with or without woundinge2
- Interactor
- Fusarium isolatese3pathogen
- Outcome
- pathogenice3
- Qualifier
- causing root rot, leaf necrosise3
- Comparator
- control treatmente3
- Setting
- greenhousee2
Not reportedDirection
Verbatim
e2“The pathogenicity of each isolate was assessed on flue-cured tobacco cultivar K326 seedlings at the six-leaf stage in greenhouse inoculation experiments with or without wounding”
e3“All 15 Fusarium isolates were pathogenic, causing root rot, leaf necrosis, and reduced growth parameters compared with the control treatment”
Claim · model-written summary
Fusarium isolate inoculation reduced growth parameters of flue-cured tobacco seedlings compared with the control treatment.
Verbatim
e2“The pathogenicity of each isolate was assessed on flue-cured tobacco cultivar K326 seedlings at the six-leaf stage in greenhouse inoculation experiments with or without wounding”
e3“All 15 Fusarium isolates were pathogenic, causing root rot, leaf necrosis, and reduced growth parameters compared with the control treatment”
Claim · model-written summary
Aggressiveness varied among Fusarium species on tobacco, both within and between species complexes.
- Taxon
- tobacco
Nicotiana tabacume4 - Outcome
- aggressivenesse4
- Qualifier
- within the same species complex or belonging to different Fusarium species complexese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“The diversity of Fusarium species associated with Fusarium wilt of tobacco and the variability in aggressiveness among Fusarium species within the same species complex or belonging to different Fusarium species complexes”
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