Abstract
In a survey for Fusarium root rot, soybean plants were sampled from eight counties across Iowa in 2008 to 2009. Fusarium isolates were recovered from surface-sterilized symptomatic and asymptomatic root tissue by culturing on peptone PCNB agar (2). Single-spore isolates were transferred to carnation leaf agar (CLA) and potato dextrose agar (PDA) for morphological identification; 11 isolates were identified as F. armeniacum (Forbes, Windels, and Burgess) Burgess and Summerell (previously F. acuminatum ssp. armeniacum) (2). Colonies on PDA produced white aerial mycelium, red to apricot pigment in agar, and bright orange sporodochia in the center of the culture. Some isolates produced a pionnotal form of slow-growing colonies with little aerial mycelium and abundant orange sporodochia. On CLA, macroconidia in orange sporodochia on carnation leaves and chlamydospores formed abundantly, but microconidia were absent (2). Species identity for the 11 isolates was confirmed by sequencing of the elongation factor gene (EF1-α) using ef1 and ef2 primers (4) (reference sequences deposited in GenBank JX101763 and JX101764). Pathogenicity of seven F. armeniacum isolates was tested using surface-sterilized soybean seed, cv. AG2403, in a petri dish assay with 3-day-old cultures on 2% water agar (1). Germination, seed rot, and lesion development were scored 7 dai using an ordinal scale (1). The experiment was a completely randomized design (CRD), had three replicate plates per isolate, and was conducted twice. All seven isolates were pathogenic on soybean, though variation in aggressiveness was observed among isolates (P < 0.0001) related to colony morphology on PDA. Seed germination was 0 to 40% when inoculated with four isolates showing white fluffy aerial mycelium on PDA. Seedlings were severely stunted with dark brown lesions covering a majority of the root system. When inoculated with three isolates showing the pionnotal form of slow-growing mycelium, germination was 70 to 100%, with few small brown lesions (~5 to 10 mm) on the roots. Noninoculated controls showed 100% germination and no symptoms. Pathogenicity was also tested in a growth chamber assay at 18°C using autoclaved soil mixed with an infested sand-cornmeal inoculum (3). Data for dry root and shoot weights and root rot severity (visually scored on a % scale) were collected at 6 weeks. The CRD experiment had five replications (single plant in a cone containing 150 ml infested soil), and was conducted twice. Root symptoms and similar variation in aggressiveness among isolates (based on colony morphology) was observed in inoculated plants. Isolates differed significantly for effects on root weight (P = 0.0125), shoot weight (P = 0.0035), and root rot severity (P = 0.0158). F. armeniacum was reisolated from infected root tissue, but not from noninoculated controls. Recovered isolates maintained their original colony morphology. F. armeniacum was previously reported in Minnesota on symptomless corn (2), but it has not been reported on soybean and its pathogenicity has not been established on any crop. To our knowledge, this is the first report of F. armeniacum as a pathogen on soybean in the United States. References: (1) K. E. Broders et al. Plant Dis. 91:727, 2007. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, UK, 2006. (3) G. P. Munkvold and J. K. O'Mara. Plant Dis. 86:143, 2002. (4) K. O'Donnell et al. Proc. Natl. Acad. Sci. 95:2044, 1998.
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Claims 12
Claim · model-written summary
Eleven isolates from soybean roots were identified as F. armeniacum.
- Taxon
- Soybean
Glycine maxt0 - Interactor
- F. armeniacumFusarium armeniacume0pathogen
- Outcome
- 11 isolates were identified as F. armeniacume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“11 isolates were identified as F. armeniacum”
t0“Soybean”
Claim · model-written summary
All seven tested isolates were pathogenic on soybean with varying aggressiveness.
- Taxon
- soybeanGlycine maxe0
- Treatment
- seven isolatese0
- Interactor
- isolatese0pathogen
- Outcome
- pathogenic on soybeane0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All seven isolates were pathogenic on soybean, though variation in aggressiveness was observed among isolates (P < 0.0001)”
Claim · model-written summary
Seed germination was 0 to 40% after inoculation with four fluffy isolates.
- Taxon
- soybeanGlycine maxt0
- Treatment
- inoculated with four isolatese0
- Interactor
- isolatese0pathogen
- Outcome
- Seed germinatione0
- Value
- 0 to 40%e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed germination was 0 to 40% when inoculated with four isolates showing white fluffy aerial mycelium on PDA.”
t0“Soybean”
Claim · model-written summary
Seedlings had severe stunting and extensive dark root lesions after inoculation.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- Seedlingse0
- Outcome
- severely stunted with dark brown lesionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seedlings were severely stunted with dark brown lesions covering a majority of the root system.”
t0“Soybean”
Claim · model-written summary
Germination was 70 to 100% after inoculation with three pionnotal isolates.
- Taxon
- soybeanGlycine maxt0
- Treatment
- inoculated with three isolatese0
- Interactor
- isolatese0pathogen
- Outcome
- germinatione0
- Value
- 70 to 100%e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When inoculated with three isolates showing the pionnotal form of slow-growing mycelium, germination was 70 to 100%”
t0“Soybean”
Claim · model-written summary
Pionnotal isolates produced few small brown root lesions.
- Taxon
- soybeanGlycine maxt0
- Outcome
- few small brown lesionse0
- Value
- ~5 to 10 mme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with few small brown lesions (~5 to 10 mm) on the roots”
t0“Soybean”
Claim · model-written summary
Noninoculated controls had 100% germination and no symptoms.
- Taxon
- soybeanGlycine maxt0
- Outcome
- 100% germination and no symptomse0
- Value
- 100%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Noninoculated controls showed 100% germination and no symptoms.”
t0“Soybean”
Claim · model-written summary
Isolates differed significantly in effects on root weight.
- Taxon
- soybeanGlycine maxt0
- Interactor
- Isolatese0pathogen
- Outcome
- root weighte0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolates differed significantly for effects on root weight (P = 0.0125)”
t0“Soybean”
Claim · model-written summary
Isolates differed significantly in effects on shoot weight.
- Taxon
- soybeanGlycine maxt0
- Interactor
- Isolatese0pathogen
- Outcome
- shoot weighte0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolates differed significantly for effects on root weight (P = 0.0125), shoot weight (P = 0.0035)”
t0“Soybean”
Claim · model-written summary
Isolates differed significantly in root rot severity.
- Taxon
- soybeanGlycine maxt0
- Interactor
- Isolatese0pathogen
- Outcome
- root rot severitye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Isolates differed significantly for effects on root weight (P = 0.0125), shoot weight (P = 0.0035), and root rot severity (P = 0.0158)”
t0“Soybean”
Claim · model-written summary
F. armeniacum was recovered from infected roots but not controls.
- Taxon
- soybeanGlycine maxt0
- Interactor
- F. armeniacumFusarium armeniacume0pathogen
- Outcome
- reisolated from infected root tissuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“F. armeniacum was reisolated from infected root tissue, but not from noninoculated controls.”
t0“Soybean”
Claim · model-written summary
This is reported as the first observation of F. armeniacum pathogenic on soybean in the United States.
- Taxon
- soybeanGlycine maxe0
- Interactor
- F. armeniacumFusarium armeniacume0pathogen
- Outcome
- first report of F. armeniacum as a pathogen on soybeane0
- Setting
- United Statese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“first report of F. armeniacum as a pathogen on soybean in the United States.”
The same questions in other papers
inoculation · growth · Glycine max (soybean)Positive and negative results
34 papers in the same direction as this paper · 323 in the opposite direction
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