First report of soybean root rot caused by Fusarium falciforme in the Republic of Korea.

Phytopathogenic Fusarium species causing root and stem rot diseases in susceptible soybean (Glycine max (L.) Merrill) are a major threat to soybean production worldwide. Several Fusarium species have been reported to infect soybean plants in the Republic of Korea, including F. solani, F. oxysporum, F. fujikuroi, and F. graminearum (Cho et al., 2004; Choi et al., 2019; Kang et al., 2020). During the nationwide survey of soybean diseases in 2015, soybean plants showing symptoms of leaf chlorosis, wilting, and shoot death were found in soybean fields in Seosan, Chungnam. Fusarium isolates were obtained from the margins of sterilized necrotic symptomatic and asymptomatic regions of the stem tissues of diseased samples by culturing on potato dextrose agar (PDA). To examine the morphological characteristics, isolates were cultured on PDA at 25°C in the darkness for 10 days. Colonies produced white aerial mycelia with apricot pigments in the medium. Macroconidia were hyaline, slightly curved in shape with 3 or 4 septa, and their average length and width were 34.6± 0.56 µm (31.4 to 37.8 µm) and 4.7±0.16 µm (4.1 to 5.8 µm), respectively (n = 20). Microconidia were elongated, oval with 0 or 1 septum, and their average length and width were 11.4±0.87 and 5.2±0.32 µm, respectively (n = 20). The colonies and conidia exhibited morphological similarities to those of F. falciforme (Xu et al., 2022). Using the primers described by O'Donnell et al. (2008), identity of a representative strain '15-110' was further confirmed by sequencing portions of two genes, the translation elongation factor 1-alpha (EF-1α) and the second largest subunit of RNA polymerase II (RPB2). The two sequences (GenBank accession No. OQ992718 and OR060664) of 15-110 were 99% similar to those of two F. falciforme strains, 21BeanYC6-14 (GenBank accession nos. ON375419 and ON331931), and 21BeanYC6-16 (GenBank accession nos. ON697187 and ON331933). To test the pathogenicity, a single-spore isolate was cultured on carnation leaf agar (CLA) at 25℃ for 10 days. Pathogenicity test was performed by root-cutting assays using 14-day-old soybean seedlings of 'Daewon' and 'Taekwang'. Ten-day-old mycelia of 15-110 were collected from the CLA plates by scraping with distilled water, and the spore suspension was filtered and diluted to 1 × 106 conidia/mL. The roots of the soybean seedlings were partially cut and inoculated by soaking in the diluted spore suspension for two hours. The seedlings were then transplanted into 12 cm plastic pots (11 cm in height) and grown in a growth chamber at 25°C, 14h light/10h dark for 2 weeks. The infected plants exhibited wilting, observed brown discoloration on the root, and eventually died within 2 weeks, whereas the control plants inoculated with sterile water remained healthy. F. falciforme 15-110 was reisolated from infected plants, but not from the uninoculated controls. The morphology of the re-isolated fungus on PDA and its target gene sequences were identical to those of the original colony. To the best of our knowledge, this is the first report of root rot in soybean caused by F. falciforme in the Republic of Korea. Fusarium spp. induce a range of diseases in soybean plants, including root rot, damping-off, and wilt. Given the variable aggressiveness and susceptibility to fungicides among different Fusarium species, it is imperative to identify the Fusarium species posing a threat to soybean production. This understanding is crucial for developing a targeted and tailored disease management strategy to control Fusarium diseases.

Very Early Pulsed Dye Laser Intervention for Optimal Cosmetic Outcome in Post-Thyroidectomy Scars.

Purpose: Early intervention of surgical scars with a pulsed dye laser is known to effectively prevent pathologic scars. Despite multiple reports on the effectiveness of the treatment, very few studies have demonstrated its appropriate initiation timing. In this study, our objective was to determine the optimal timing for initiating laser treatment following thyroidectomy. Methods: This study retrospectively analyzed 91 patients undergoing pulsed dye laser treatment post-thyroidectomy, grouping them by treatment initiation timing. The patients underwent treatment at intervals of 3-4 weeks with at least five sessions. Those with a high pliability score were injected with intralesional corticosteroids. The Antera 3D® skin imaging analyzer was used to assess biophysical parameters. Results: The total Vancouver Scar Scale score significantly reduced after treatment in all groups. The Vancouver Scar Scale score reduction rate was significantly higher after treatment in the group for which the treatment was initiated within 3 weeks of surgery. The pigmentation and erythema score analyzed by Antera 3D® was also lower in this group. Conclusion: Early intervention using a pulsed dye laser within 3 weeks of thyroidectomy can substantially inhibit pathological scar development, providing physicians with a guide for optimal treatment commencement.

First report of soybean root rot caused by Fusarium proliferatum in the Republic of Korea.

Fusarium species are widespread soilborne pathogens that can cause damping-off, root rot, and wilting in soybean [Glycine max (L.) Merrill], subsequently leading to significant yield suppression. Several Fusarium spp. have already been documented for their pathogenicity on soybean plants in the Republic of Korea. The nationwide monitoring of soybean diseases continues to identify new pathogenic Fusarium spp. In 2016, five plant samples at R3-R4 growth stages, showing symptoms of wilting in the upper parts and root rot, were collected in Suwon, Gyeonggi, Republic of Korea. Fungal colonies were obtained from the diseased root samples, with the surface sterilized in 1% sodium hypochlorite for 2 min, rinsed thrice with sterile distilled water, and placed on water agar at 25°C. Five isolates were collected and purified by single-spore isolation. The fungal mycelium was subsequently cultivated on potato dextrose agar for ten days. The isolates produced abundant, aerial, and white mycelium and became purple in old cultures. Macroconidia were slender, falcate to almost straight, usually 3 to 5 septated, and thin-walled. Microconidia were formed in chains from polyphalides, clavate or oval, usually single-celled with a flattened base. These characteristics of isolates were consistent with the description of F. proliferatum (Leslie and Summerrell 2006), and the representative isolate 16-19 was selected for molecular identification to confirm its identity as F. proliferatum. Two evolutionarily conserved genes, the translation elongation factor 1-alpha (EF-1α) and the second-largest subunit of RNA polymerase II (RPB2) genes, were partially amplified using the primers described by O'Donnell et al. (2008), resulting in nucleotide sequences of 680 and 382 base pairs, respectively. These two sequences (GenBank accession numbers: OQ992720 and OR060666) showed 100 and 99.5% identity to the EF-1α and RPB2 of F. proliferatum A40 (GenBank accession numbers: KP964907 and KP964842). For the Petri-dish pathogenicity assay (Broders et al. 2007), five surface-sterilized seeds were placed on water agar media with either sterile water or actively growing '16-19' culture. After 7 days of incubation in a growth chamber (25°C; 12-hour photoperiod), brown lesions were observed on the roots of the inoculated plants, while no symptoms were observed in the sterile water-treated controls. The experiment was conducted three times. For root-cut pathogenicity assay, conidial suspension (1×106 conidia/ml) of the isolate '16-19' was prepared with harvested mycelia cultured on PDA for 10 days with sterile water. The roots of 10-day-old soybean seedlings were partially cut and soaked in either the suspension or sterile water for 2 hours. The seedlings were transplanted into 12 cm plastic pots (11 cm in height) and grew in a greenhouse (26 ± 3°C, 13-h photoperiod). The experiment followed a completely randomized design with three replicates (i.e. three plants in a pot), and it was repeated twice. The inoculated plants began to wilt 7 days after inoculation, while the sterile water-treated controls remained healthy. Ten days after inoculation, all plants were collected, washed under running tap water, and evaluated for the presence and severity of root rot using a 0-4 scale (Chang et al. 2015). The inoculated plants exhibited reduced vigor and developed dark brown lesions on their roots. F. proliferatum was reisolated from symptomatic root tissues of the infected plants, while not from those of the controls. Its colony and spores were morphologically identical to those of the original isolate. F. proliferatum was previously reported as a causative agent of soybean root rot in the United States (Díaz Arias et al. 2011) and Canada (Chang et al. 2015). This is the first report of soybean root rot caused by F. proliferatum in the Republic of Korea. This finding implies that F. proliferatum may potentially threaten soybean production in the Republic of Korea and suggests that effective disease management strategies should be established for soybean protection against the disease, along with continuous surveillance.

Development of a Gene-Based Soybean-Origin Discrimination Method Using Allele-Specific Polymerase Chain Reaction.

A low soybean self-sufficiency rate in South Korea has caused a high import dependence and considerable price variation between domestic and foreign soybeans, causing the false labeling of foreign soybeans as domestic. Conventional soybean origin discrimination methods prevent a single-grain analysis and rely on the presence or absence of several compounds or concentration differences. This limits the origin discrimination of mixed samples, demonstrating the need for a method that analyzes individual grains. Therefore, we developed a method for origin discrimination using genetic analysis. The whole-genome sequencing data of the Williams 82 reference cultivar and 15 soybean varieties cultivated in South Korea were analyzed to identify the dense variation blocks (dVBs) with a high single-nucleotide polymorphism density. The PCR primers were prepared and validated for the insertion-deletion (InDel) sequences of the dVBs to discriminate each soybean variety. Our method effectively discriminated domestic and foreign soybean varieties, eliminating their false labeling.