Article ; Online: First Report of Root Rot Caused by Fusarium commune on American Ginseng (Panax quinquefolium) in China
Plant Disease. 2023 Aug. 01, v. 107, no. 8 p.2539-
2023
Abstract: American ginseng (Panax quinquefolium L.) is one of the most valuable herbal crops because of its unique pharmacological properties. In 2019, American ginseng plants withered, and root rot with an incidence of 20 to 45% was observed in an about 70,000-m² ...
| Abstract | American ginseng (Panax quinquefolium L.) is one of the most valuable herbal crops because of its unique pharmacological properties. In 2019, American ginseng plants withered, and root rot with an incidence of 20 to 45% was observed in an about 70,000-m² ginseng production field located in the mountainous valley of Benxi city (41°23′32″N, 124°04′27″E), Liaoning Province, China. Disease symptoms included chlorotic leaves with dark brown discoloration extending gradually from the basal to the apical part of the leaves. Water-soaked, irregular lesions appeared on the surface of roots, which became rotten at the later stage. Twenty-five symptomatic roots were surface sterilized by immersion in 2% sodium hypochlorite (NaOCl) for 3 min, followed by rinsing three times in sterilized water. The sections of healthy tissue–bordered rotten tissues, that is, the leading edge, were cut into 4- to 5-mm pieces with a sterile scalpel, and four pieces were placed on each PDA plate. After 5 days of incubation at 26°C, a total of 68 single spores were obtained from the colonies with an inoculation needle and observed under a stereomicroscope. Colonies from single conidia were white to greyish white and densely floccose to fluffy, and the reverse side was grayish yellow with dull violet pigmentation. Single-celled, ovoid microconidia in false heads were borne on aerial monophialidic or polyphialidic conidiophores on carnation leaf agar media and measured 5.0 to 14.5 × 3.0 to 4.8 μm (n = 25). Macroconidia were two to four septate and slightly curved, apical and basal cells were also curved, and they measured 22.5 to 45.5 × 4.5 to 6.3 μm (n = 25). Chlamydospores were singly or in pairs, circular or subcircular, smooth, and measured 5 to 10.5 μm (n = 25) in diameter. Morphologically, the isolates were identified as Fusarium commune (Leslie and Summerell 2006; Skovgaard et al. 2003). To confirm the identity, the rDNA partial translation elongation factor 1-alpha (TEF-α) gene and the internal transcribed spacer (ITS) region of 10 isolates were amplified and sequenced (O’Donnell et al. 2015; White et al. 1990). Identical sequences were obtained, and one representative sequence of the isolate BGL68 was submitted to GenBank. BLASTn analysis of both TEF-α (MW589548) and ITS (MW584396) sequences revealed 100 and 99.46% sequence identity to F. commune MZ416741 and KU341322, respectively. The pathogenicity test was conducted under greenhouse conditions. The surface of 2-year-old healthy American ginseng roots was washed and disinfested in 2% NaOCl for 3 min before rinsing in sterilized water. Twenty roots were wounded with a toothpick, resulting in tiny perforations (1.0 × 1.0 × 3.0 mm), and three perforations were wounded on each root. Inoculum was prepared from the culture of the isolate BGL68 incubated in potato dextrose broth on a shaker for 5 days at 26°C and 140 rpm. Ten wounded roots were immersed in a conidial suspension (2 × 10⁵ conidia/ml) for 4 h in a plastic bucket and planted in five containers (two roots per container) filled with sterile soil. Another 10 wounded roots were immersed in sterilized distilled water and planted in five containers as controls. The containers were incubated for 4 weeks in a greenhouse at temperature between 23 and 26°C, under a 12-h light/dark regime, and irrigated with sterile water every 4 days. Three weeks after inoculation, all inoculated plants exhibited chlorotic leaves, wilting, and root rot. The taproot and the fibrous roots showed brown to black root rot, whereas no symptoms appeared in the noninoculated controls. The fungus was reisolated from the inoculated plants, but not from any of the control plants. The experiment was repeated two times with similar results. This is the first report of root rot caused by F. commune on American ginseng in China. The disease might bring a threat to this ginseng production, and effective control measures should be implemented to reduce losses. |
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| Keywords | Dianthus caryophyllus ; Fusarium ; Panax quinquefolius ; agar ; black root rot ; chlamydospores ; conidia ; conidiophores ; discoloration ; fungi ; genes ; greenhouses ; inoculum ; internal transcribed spacers ; leaves ; mountains ; pathogenicity ; peptide elongation factors ; pigmentation ; sequence analysis ; sodium hypochlorite ; soil ; tap roots ; temperature ; China ; American ginseng (Panax quinquefolium L.) ; Fusarium commune ; root rot |
| Language | English |
| Dates of publication | 2023-0801 |
| Publishing place | The American Phytopathological Society |
| Document type | Article ; Online |
| ZDB-ID | 754182-x |
| ISSN | 0191-2917 |
| ISSN | 0191-2917 |
| DOI | 10.1094/PDIS-10-21-2347-PDN |
| Database | NAL-Catalogue (AGRICOLA) |
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