Abstract
During November of 2003, Chinese radishes (Raphanus sativus cv. Taibai) harvested in St. Catharines, Ontario and stored in less than 1°C with 98% relative humidity (RH) and 5°C with 96% RH showed symptoms of black and dark brown, irregular patches, with or without decay. The symptoms were closely associated with skin wounds and damaged root hairs. Fungal DNA was extracted from discolored skin samples peeled from a radish, and 18S rRNA genes were amplified with fungal-specific PCR primers (1) EF4f (5′-ggaagggrtgtatttattag-3′) and EF3r (5′-tcctctaaatgaccagtttg-3′). The cloned genes were sequenced using the primer EF4f and compared directly with nonredundant nucleotides in GenBank with BLAST. The results indicated that more than 75% of the fungal microflora on the diseased radish were Alternaria spp. Alternaria sp. was successfully isolated from discolored and decayed radish tissues. Morphological and molecular identification indicated that the isolated Alternaria sp. cultures belong to A. raphani, which was previously reported to cause leaf and pod blight on radish (2). For pathogenicity studies, a spore suspension (1 × 10 5 conidia/ml) obtained from a 4-week-old A. raphani culture was used to inoculate ‘Taibai’ Chinese radish tissues, including inner tissues and wounded and nonwounded skin. All tests were carried out at room temperature (22 to 24°C). On inner tissue and wounded skin, symptoms of dark brown-to-black patches appeared 2 days after inoculation and progressed with time. No symptoms developed on the noninoculated control or the nonwounded, inoculated treatment. A. raphani was reisolated from symptomatic tissue. Further evidence of pathogenicity was obtained by an additional inoculation and observation of symptoms. The results indicated that A. raphani was the causal agent of the black patches observed on Chinese radish, and to our knowledge, this is the first report that A. raphani could cause a postharvest disease on Chinese radish in storage. References: (1) J. D. Van Elsas et al. J. Microbiol. Methods 43:133, 2000. (2) M. S. Sangwan et al. J. Mycol. Plant Pathol. 32:125, 2002.
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Claims 7
Claim · model-written summary
Inoculation of Chinese radish tissue with an A. raphani spore suspension produced dark brown-to-black patches, while the noninoculated control showed none.
- Taxon
- Chinese Radish
Raphanus sativus var. nigert0 - Treatment
- spore suspensione1
- Interactor
- Alternaria raphaniAlternaria japonicat0pathogen
- Outcome
- dark brown-to-black patchese3
- Comparator
- noninoculated controle2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e1“For pathogenicity studies, a spore suspension”
e2“No symptoms developed on the noninoculated control”
e3“On inner tissue and wounded skin, symptoms of dark brown-to-black patches appeared 2 days after inoculation”
Claim · model-written summary
Alternaria sp. was successfully isolated from discolored and decayed radish tissues.
- Taxon
- radish
Raphanus sativuse4 - Interactor
- Alternaria sp.
Alternariae4pathogen - Outcome
- successfully isolatede4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e4“Alternaria sp. was successfully isolated from discolored and decayed radish tissues”
Claim · model-written summary
More than 75% of the fungal microflora on diseased radish were Alternaria spp.
- Taxon
- radishRaphanus sativuse5
- Interactor
- Alternaria sppAlternariae5pathogen
- Outcome
- fungal microflorae5
- Value
- more than 75%e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e5“more than 75% of the fungal microflora on the diseased radish were Alternaria spp”
Claim · model-written summary
Morphological and molecular identification places the isolated Alternaria sp. cultures in A. raphani.
- Taxon
- Chinese RadishRaphanus sativus var. nigert0
- Interactor
- A. raphaniAlternaria japonicae6pathogen
- Outcome
- isolated Alternaria sp. culturese6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e6“Morphological and molecular identification indicated that the isolated Alternaria sp. cultures belong to A. raphani”
Claim · model-written summary
A. raphani is reported as a first cause of postharvest disease on Chinese radish in storage.
- Taxon
- Chinese radishRaphanus sativus var. nigere7
- Interactor
- A. raphaniAlternaria japonicae7pathogen
- Outcome
- postharvest diseasee7
- Qualifier
- in storagee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e7“this is the first report that A. raphani could cause a postharvest disease on Chinese radish in storage”
Claim · model-written summary
Symptoms appeared on wounded skin after inoculation, but not on nonwounded skin.
- Taxon
- Chinese RadishRaphanus sativus var. nigert0
- Treatment
- wounded skine3
- Interactor
- Alternaria raphaniAlternaria japonicat0pathogen
- Outcome
- symptomse3
- Comparator
- nonwounded, inoculated treatmente4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e3“On inner tissue and wounded skin, symptoms of dark brown-to-black patches appeared 2 days after inoculation”
e4“No symptoms developed on the noninoculated control or the nonwounded, inoculated treatment”
Claim · model-written summary
A. raphani was reisolated from symptomatic radish tissue.
- Taxon
- Chinese RadishRaphanus sativus var. nigert0
- Interactor
- A. raphaniAlternaria japonicae4pathogen
- Outcome
- reisolated from symptomatic tissuee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Alternaria raphani Causing Black Patches on Chinese Radish”
e4“A. raphani was reisolated from symptomatic tissue”