RESUMEN
Epimedium sagittatum (Sieb.et Zucc.) Maxim., a perennial herb, is an important medicinal plant, rich in flavonoids, and widely used in the treatment of sexual dysfunction, rheumatic disease, and cancers (Tan et al. 2016). In July 2022, a disease of root and rhizome was found on E. sagittatum aged 1-8 years in a planting area (266 ha) of Zhumadian City (32°58'12" N, 114°37'48" E), Henan Province, China. The disease incidence per field (660 m2) was around 10-15% in six randomly surveyed fields planted with about 10,000 E. sagittatum plants each. Symptoms included leaf yellowing, root and rhizome browning, rotting and necrosis, and eventually the whole plant wilted and died. Fifteen plants with symptoms were sampled to isolate the pathogen. Symptomatic tissues were cut into small pieces of 5×5 mm, surface sterilized with 75% ethanol for 30 s, followed by three rinses with sterile double-distilled water (ddH2O). The pieces were then surface disinfected with 0.1% HgCl2 for 30 s, rinsed three times with sterile ddH2O, placed onto potato dextrose agar (PDA) plates and incubated at 28°C in the dark for 5 days. Twelve deferent Fusarium spp. colonies were purified by excising hyphal tip onto PDA for cultivation. Pathogenicity test of all strains was performed. Only isolate GY2 could result in root and rhizome rot of host plant. Colonies of GY2 on PDA had abundant white aerial mycelia with yellow halo. Macroconidia were hyaline, falciform, with a slightly curved apical cell and blunt basal cell, 29.7~45.0 (average 38.3) × 4.5~6.6 (average 5.3) µm (n =50), with 2-3 septa. Microconidia were oval, or reniform, hyaline, 8.4~26.5 (average 16.5) × 2.7~6.0 (average 4.5) µm (n =50), with 0-2 septa. Morphological characteristics of isolate GY2 were consistent with those of the Fusarium solani species complex (FSSC) (Chehri et al. 2015). For molecular identification, a region of the translation elongation factor 1-α (TEF) and RNA polymerase second largest subunit (RPB2) of GY2 were PCR-amplified and sequenced using the primers EF1-728F/986R (Carbone et al. 1999) and RPB2-5f2/7cr (O'Donnell et al. 2010), respectively. The TEF and RPB2 sequences (GenBank accession nos. OR978135.1 and OR978136.1) of GY2 were concatenated for a phylogenetic analysis using the Bayesian method (Zhang et al. 2020). The phylogenetic tree revealed that isolate GY2 clustered with F. falciforme with a credibility value of 99%. Morphological and molecular results support identification of isolate GY2 as F. falciforme. A pathogenicity test was performed on 4-year-old healthy plants grown in pots. Twenty healthy plants were inoculated by pouring a 200 mL conidial suspension (1×106 conidia/mL) around the rhizome. Control plants received 200 mL of sterile ddH2O. All treatments were maintained in a greenhouse at 25±1°C and 80% relative humidity. The assay was conducted three times. After 20 days, similar symptoms as those in the field were observed on the inoculated plants, whereas controls remained asymptomatic. Fusarium falciforme was reisolated from the symptomatic plants and showed the same morphological and molecular characteristics as isolate GY2, fulfilling Koch's postulates. Fusarium falciforme was reported to cause root rot of tobacco (Qiu et al. 2023) and industrial hemp (Paugh et al. 2022). However, this is the first report of F. falciforme causing root and rhizome rot of E. sagittatum. Our study will contribute to the development of strategies for the effective management of this disease on E. sagittatum.
RESUMEN
Epimedium sagittatum (Sieb.et Zucc.) Maxim. is an important material of traditional Chinese medicine because of the rich content of flavonoids that are used to treat osteoporosis, liver cancer, and sexual dysfunction (Liu et al. 2013). A leaf blight was observed on E. sagittatum in Zhumadian City, China (32°58'12" N, 114°37'48" E, continental monsoon climate) in June 2021. Survey indicated that about 18% of the plants were infected in a 266-ha commercial planting area. The initial symptoms were white patches with tan borders, irregular in outline, with small black particles visible on the center of the lesions. In a week or so, patches extended throughout the leaf, and then leaves withered. Thirty leaves with symptoms collected from five different sites were cut into 5×5 mm pieces, and then surface-sterilized with 75% ethanol for 15 s followed by rinsing with double distilled water (ddH2O) three times. The pieces were then disinfested with 0.1% HgCl2 solution for 30 s, and rinsed with ddH2O, then placed onto potato-dextrose agar medium (PDA) and incubated in the dark for 3 d at 28°C. Eight fungal isolates were purified; of these, only the isolate HY2-1 infected the host plant and was selected for further morphological characterization. The colonies of HY2-1 were olive green with loose aerial hyphae on PDA. Conidiophores were single or branched, producing brown conidia in short chains. Conidia were obclavate, obpyriform, or ellipsoidal, 15.9-47.3 µm × 7.6-16.6 µm (n=50) and pale brown or dark brown with a short cylindrical beak at the tip that contained 1-5 transverse septa and 0-4 longitudinal septa. Morphological characteristics of the isolate were identical with those of Alternaria species (Huang et al. 2022). For molecular identification, the internal transcribed spacers (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Weir et al. 2012), major allergen Alt a 1(Alt a 1) and translation elongation factor 1-α gene (TEF) (Lawrence et al. 2013) were amplified and sequenced using the primers ITS4/5, GDF/GDR, Alt-F/R, and EF1-728F/986R, respectively. The results of the sequencing were uploaded to GenBank as ITS (OR418487), GAPDH (OR419792), Alt a 1 (OR419794), and TEF (OR419796), respectively. Phylogenetic analyses were performed by concatenating all the sequenced loci using the Bayesian method in Phylosuite (Zhang et al.2020). The phylogenetic tree indicated that the isolate belongs to the A. alternata clade with a bootstrap value of 75%. The pathogen was identified as A. alternata based on the morphological and molecular results. To satisfy Koch's postulates, a conidial suspension (106 conidia/mL) of the HY2-1 was prepared with ddH2O to infect the healthy plants. Ninety healthy leaves on 30 plants in pots were punctured using a sterilized needle, and then inoculated by spraying the conidial suspension on the wounded leaves in a greenhouse at 25°C and 80% relative humidity. The control plants were sprayed with ddH2O. The plants showed similar symptoms to the original infected plant 15 d after inoculation. The controls showed no symptoms. A pure culture of A. alternata was isolated and identified again as previously described. Leaf blight caused by A. alternata has been reported on Taro (Liu et al. 2020), Toona ciliata (Wang et al. 2023), etc. To our knowledge, this is the first report of E. sagittatum leaf blight caused by A. alternata in China. The results will help to develop effective control strategies for leaf blight on E. sagittatum.
RESUMEN
Epimedium sagittatum (Sieb.et Zucc.) Maxim., belonging to the family Berberidaceae and genus Epimedium, is a perennial herb widely studied for its anti-osteoporosis, anti-cancer, and anti-sexual-dysfunction effects in Asian countries (Tan et al. 2016; Zhang et al. 2016). High levels of bioactive chemicals in Epimedium spp. has endowed it with important clinical and commercial values (Liu et al. 2013). In September 2021, a leaf disease was found in Zhumadian City, China (32°58'12" N, 114°37'48" E). Survey statistics indicated that disease prevalence in a 266-ha planting area was approximately 29.6%. The lesions appeared at the leaf tips, gradually enlarged, and were brown with a yellow halo. Further, the lesions were dry with distributed black spots. Thirty infected leaves collected from five sites within the planting base . The collected leaves were cut into 5×5 mm pieces , surface-sterilized in 75% alcohol for 15 s, triple washed with sterile ddH2O, disinfested with 0.1% HgCl2 solution for 30 s (Liu et al. 2021), triple washed again with sterilized ddH2O, and then placed onto PDA and incubated in the dark for 3 d at 28°C. Subsequently, five fungal strains were purified; among them, only the isolate HY3-2 infected the host plant and was selected for further morphological characterization. The colonies of HY3-2 initially appeared white, their mycelia became gray at the center after 4 d, and orange-red conidial clumps appeared in them after 7 d. Conidia (10.0-19.5 µm × 4.5-5.6 µm, n=50) were single celled, nearly spherical or stick-shaped and colorless. Morphological characteristics of the isolate were consistent with those of Colletotrichum species. Additionally, glycerol-3-phosphate dehydrogenase (gapdh), actin (act), calmodulin (cal), ß-tubulin 2 (tub2), and chitin synthase-1 (chs-1), (Weir et al. 2012) were amplified and sequenced using the primers GDF/GDR, ACT-512F/783R, CL1C/CL2C, T1/Bt2b, and CHS-79F/354R, respectively for molecular identification. The resulting sequences were deposited in GenBank: gapdh (ON351609), act (ON351608), tub2 (ON351610), chs-1 (ON532788), and cal (ON532787). Phylogenetic analyses were performed by concatenating all the sequenced loci using the Bayesian method (Zhang et al. 2020). The phylogenetic tree showed that the isolate belongs to C. fructicola clade with a credibility value of 85%.To satisfy Koch's postulates, a conidial suspension (106 conidia/mL) of the isolate HY3-2 were prepared with sterile ddH2O to infect the leaves. Ninety healthy leaves from 30 plants in pots were punctured using a sterilized needle (Huang et al. 2022), and inoculated by spraying the conidial suspension on the leaves in a greenhouse at 25°C and 80% relative humidity. In the control plants, the suspension was replaced with water. After 7 d, the inoculated plants showed symptoms similar to those of the original infected plant, whereas the control showed no symptoms. C. fructicola was isolated and identified again as previously described. A pathogenicity test was also conducted in the field using the same method as that used in the greenhouse in July 2022, the results of which were consistent with those of the greenhouse. In China, C. fructicola has been reported on Walnut (Wang et al. 2022), Punica granatum (Hu et al. 2023) and others. To our knowledge, this is the first report of C. fructicola causing anthracnose in E. sagittatum in China. This report provides an important basis for further disease control research.
