First Report of Nigrospora oryzae Causing Leaf Spot on Peanut (Arachis hypogaea L.) in the Republic of Korea.

Peanut (Arachis hypogaea L.) is one of the most profitable upland crops, yielding 10,711 tonnes in an area of 4,062 ha in the Republic of Korea (Ministry of Agriculture, Food and Rural Affairs 2023). In September 2023, dark gray spots surrounded by yellow halos were observed on the peanut leaves over an area of 880 m2 at the National Institute of Crop Science (35°50'31.4"N 127°02'41.0"E), with a disease incidence up to 80%. Early symptoms appeared as small, brown, circular or irregular spots that enlarged and were surrounded by chlorotic halos. Leaf cuttings (5 mm x 5 mm) from five symptomatic plants were surface-sterilized with 70% EtOH for 1 min, followed by 1% NaClO for 1 min, and rinsed 3 times with sterile water. The pieces were placed on Potato Dextrose Agar (PDA) and incubated at 25 °C in the dark for 3 days. Three isolates obtained by single-spore isolation were designated as F23025, F23026, and F23027. Two isolates, F23025 and F23026 were deposited in the Korean Agricultural Culture Collection (https://genebank.rda.go.kr) under the accession numbers 410722 and 410723. Fungal colonies were initially white and turned sooty gray after 5 days. Conidia were unicellular, brown to black, and spherical or sub-spherical with 6.8 µm to 14.3 µm (mean = 11.1 µm ± 1.8, n = 50). The morphology of the three isolates was identical and showed the same characteristics as Nigrospora oryzae (Ellis 1971; Hudson 1963). For molecular identification, the Internal Transcribed Spacer (ITS) region (GenBank accession PP388306 and PP574448), beta tubulin (PP397027 and PP580108), and translation elongation factor 1- ɑ (PP397028 and PP580109) of isolates F23025 and F23026 were amplified and sequenced with primers of ITS5/ITS4, Bt2a/Bt2b, EF1-727F/EF2, respectively and showed high identity of 99.62% (530 bp/532 bp), 100% (384/384), and 99.79% (475/476) with N. oryzae strain LC2693 (GenBank accessions KX985994, KY019471, and KY019299, respectively). Multilocus sequence analysis showed isolates F23025 and F23026 were on the same clade with N. oryzae strain LC2693. To determine the pathogenicity to peanut, a conidial suspension (1 x 106 conidia/mL) was sprayed onto leaves of five 3-week-old plants 'Sewon' grown in pots, while sterile distilled water was sprayed onto two plants used as negative control. Sprayed plants were placed in a dew chamber at 25℃ for two days and grown in a growth chamber at 25℃ and 80% of relative humidity with a 16L:8D cycle. Two weeks later, dark spots with chlorotic halos appeared only on leaves sprayed with conidia, and no symptoms on leaves sprayed with sterile distilled water. The pathogenicity test was repeated three times, and each time the pathogen was re-isolated and identified by ITS sequence, thus fulfilling Koch's postulates. Nigrospora species are cosmopolitan, and some species have a wide host range as plant pathogens. Recently, two species of the genus Nigrospora, N. sphaerica and N. aurantiaca, were reported to cause peanut leaf blight in China (Liu et al. 2020; He et al. 2023). To the best of our knowledge, this is the first report of N. oryzae causing leaf spot to A. hypogaea L. in the Republic of Korea. As identifying new pathogens and registering fungicides to control them are important for the continued cultivation of peanut, this report will help in that endeavor.

Analysis of Rice Blast Fungus Genetic Diversity and Identification of a Novel Blast Resistance OsDRq12 Gene.

The rice blast fungus Magnaporthe oryzae poses a significant challenge to maintaining rice production. Developing rice varieties with resistance to this disease is crucial for its effective control. To understand the genetic variability of blast isolates collected between 2015 and 2017, the 27 monogenic rice lines that carry specific resistance genes were used to evaluate blast disease reactions. Based on criteria such as viability, virulence, and reactions to resistance genes, 20 blast isolates were selected as representative strains. To identify novel resistance genes, a quantitative trait locus analysis was carried out utilizing a mixture of the 20 representative rice blast isolates and a rice population derived from crossing the blast-resistant cultivar 'Cheongcheong' with the blast-susceptible cultivar 'Nagdong'. This analysis revealed a significant locus, RM1227-RM1261 on chromosome 12, that is associated with rice blast resistance. Within this locus, 12 disease resistance-associated protein genes were identified. Among them, OsDRq12, a member of the nucleotide-binding, leucine-rich repeat disease resistance family, was chosen as the target gene for additional computational investigation. The findings of this study have significant implications for enhancing rice production and ensuring food security by controlling rice blast and developing resistant rice cultivars.

Enhanced gelling property and freeze-thaw stability of potato, tapioca and corn starches modified by mild heating in aqueous ethanol solution.

BACKGROUND: Physically modified starches can be classified as natural ingredients on food labels and clean label products. Thus, the market demand for physically modified starch is increasing. Potato, tapioca and corn starches were physically modified by mild heat treatment in an alcoholic solution to enhance their gelling property and freeze-thaw stability. RESULTS: During mild heating of starch suspension (40% w/w) in 10% ethanol solution at the onset gelatinization temperature, granular swelling of starch occurred, followed by amylose leaching with medication of the surface structure of the starch granules. All treated starches exhibited increased gelatinization and pasting temperatures and decreased breakdown for pasting as a result of improved stability against shear and heat. The treated starches had higher hardness, cohesiveness and springiness of gel than the respective native starches, and these gel properties were more pronounced in potato starch than in tapioca and corn starches. The treated starches showed substantially reduced gel syneresis during freeze-thawing. CONCLUSION: Physical modification of starch by mild heat treatment in an alcoholic solution substantially improved its gelation ability and freeze-thaw stability. © 2024 Society of Chemical Industry.

Relation between textural attributes and surface leachate structural and compositional characteristics of cooked rice.

The objective of this study was to evaluate the leachate and textural characteristics of cooked rice, and the correlations between the leachate properties and texture attributes were also investigated. Cooked waxy rice had much higher total solids and amylopectin amount in leachate than the normal and high-amylose rice. For all varieties, the amylopectin chain length of the leachate was similar, excluding Dodam cultivar. The rheological characteristics of the leachate solutions were highly dependent on the amylopectin amount of the leachate. Regarding the textural characteristics, Dodam had the highest hardness and the lowest adhesiveness. The principal component analysis showed substantial differences in leachate and textural characteristics of Korean cooked rice according to its amylose content. The adhesiveness was positively and negatively correlated with amylopectin amount of leachate and the proportion of long amylopectin chains, respectively. These results indicated that the leachate characteristics of cooked rice significantly influenced its textural attributes. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01446-3.

Comparative analysis of malt quality and starch characteristics of three South Korean barley cultivars.

In this study, malt was produced in pilot-scale facilities and conditioned using three barley (Hordeum vulgare L.) cultivars in South Korea (Heugho, Hopum, and Kwangmaeg). Quality and starch characteristics were compared. The starch content was considerably reduced in all malts. Coleoptile elongation was higher in Heugho (HHM; 85.7% ± 12.6%) and Hopum (HPM; 83.9% ± 10.7%) than in Kwangmaeg (KMM; 78.1% ± 9.9%) malt. Malt yield ranged from 81.8 to 84.9%, with no significant difference. All samples presented type A crystallinity, and granules showed discoid shapes. After malting, the mono- and di-saccharide contents (not including sucrose) were increased. The fermentable sugar level was the highest in HHM, whereas non-fermentable sugar was the highest in KMM. These results suggest that HPM enables efficient scarification based on the rapid degradation of starch, while Heugho barley and HHM have a high potential for beer and malt production, respectively. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01419-6.

Attenuation of phytofungal pathogenicity of Ascomycota by autophagy modulators.

Autophagy in eukaryotes functions to maintain homeostasis by degradation and recycling of long-lived and unwanted cellular materials. Autophagy plays important roles in pathogenicity of various fungal pathogens, suggesting that autophagy is a novel target for development of antifungal compounds. Here, we describe bioluminescence resonance energy transfer (BRET)-based high-throughput screening (HTS) strategy to identify compounds that inhibit fungal ATG4 cysteine protease-mediated cleavage of ATG8 that is critical for autophagosome formation. We identified ebselen (EB) and its analogs ebselen oxide (EO) and 2-(4-methylphenyl)-1,2-benzisothiazol-3(2H)-one (PT) as inhibitors of fungal pathogens Botrytis cinerea and Magnaporthe oryzae ATG4-mediated ATG8 processing. The EB and its analogs inhibit spore germination, hyphal development, and appressorium formation in Ascomycota pathogens, B. cinerea, M. oryzae, Sclerotinia sclerotiorum and Monilinia fructicola. Treatment with EB and its analogs significantly reduced fungal pathogenicity. Our findings provide molecular insights to develop the next generation of antifungal compounds by targeting autophagy in important fungal pathogens.

Potential Migration and Health Risks of Heavy Metals and Metalloids in Take-Out Food Containers in South Korea.

The consumption of take-out food has increased worldwide; consequently, people are increasingly being exposed to chemicals from food containers. However, research on the migration of metals from containers to food is limited, and therefore, information required to determine the health risks is lacking. Herein, the amount of transfer of nine metals and metalloids (Pb, Sb, Cd, Ge, Co, Mn, Sn, As, and Hg) from food containers to food in South Korea was assessed from take-out food containers classified into paper and plastic container groups. The sample containers were eluted over time by either warming with 4% acetic acid at 70 °C or cooling with 4% acetic acid at 100 °C /deionized water at 25 °C. It was analyzed using an inductively coupled plasma mass spectrometer and a direct mercury analyzer. The reliability of the quantitative results was verified by calculating the linearity, limit of detection, and limit of quantification. We found that the amount of metals and metalloids (Pb, Sb, Cd, and Co) eluting over time was highly significant in the plastic group. Regardless of the food simulant and elution time, the amount of Sb transferred from the food containers to food was substantially higher in the plastic (average concentration: 0.488-1.194 µg/L) than in the paper group (average concentration: 0.001-0.03 µg/L). Fortunately, all food containers were distributed at levels safe for human health (hazard index: 0.000-64.756%). However, caution is needed when warm food is added to food containers. Overall, our results provide baseline data for the management and use of take-out containers.

First report of wilt disease caused by Pythium myriotylum on peanut plants in Korea.

Peanut (Arachis hypogaea L.) has long been cultivated worldwide as an important crop for oil and protein production. Among the various diseases in peanut plants, wilt diseases caused by soil-borne pathogens such as Ralstonia solanacearum and Verticillium dahliae are especially destructive and substantially diminish both quantity and quality in peanut production (Kokalis-Burelle et al., 1997; Thiessen et al., 2012). In July 2022, wilt symptoms were observed in 1 to 3% of the area of peanut fields in Yeoju-si, Korea (37°23´04.0˝N; 127°33´43.0˝E). The xylem in the stems of the wilted plants was dark brown at the soil-surface, which is a representative symptom of vascular wilt pathogens (Yadeta et al. 2013). To isolate the causative pathogens, the stems exhibiting dark lesions were disinfected with 1% NaOCl for 1 min, rinsed with sterile distilled water, and placed on potato dextrose agar medium. The plates were incubated at 25℃ for 2 days, and white hyphae that grew out from the tissues were subcultured twice on V8 juice agar (V8A) medium. Among the 3 isolates, morphological characteristics of the representative strain YJ1-2 were observed under a microscope. The sporangia were terminal intercalary, filamentous, inflated lobulate, and ranging from 37.4 to 73.6 µm in diameter. The antheridia were diclinous, with clavate, elongate, and crook-necked shapes. The oogonia were mostly globose, with an average of 27.1 µm (range from 20.2 to 35.2 µm, n = 50) in diameter, and mated with one to several antheridia. Both plerotic or aplerotic oospores were observed. Overall, the morphological characteristics of the sporangia, antheridia, oogonia, and oospores indicated that YJ1-2 belongs to the genus Pythium. To genetically characterize YJ1-2, genomic DNA was extracted using cetyltrimethylammonium bromide buffer, and the internal transcribed spacer (ITS) region and cytochrome c oxidase subunit I (cox1) gene were amplified by PCR using primer sets ITS4/ITS5 and OomCoxI-Levlo/ OomCoxI-Levup, respectively (White et al., 1990; Robideau et al. 2011), sequenced, and identified using BLASTN (NCBI, National Center for Biotechnology Information). The ITS sequence (NCBI Acc. No. OR125595) of YJ1-2 has 99% similarity with that of P. myriotylum isolate PY39 (NCBI Acc. No. KX671096). A neighbor-joining phylogenetic tree was constructed from aligned cox1 sequence (NCBI Acc. No. OR224334) of the 10 Pythium species strains including YJ1-2 by CLUSTALW method was used as an outgroup. The YJ1-2 was most closely related to P. myriotylum isolate PM30 (NCBI Acc. No. MT823167). To substantiate the pathogenicity of YJ1-2, the crown roots of peanut plants grown in pots for 4 weeks were wounded using a sterile tweezer, and the mycelial plugs of YJ1-2 cultured for 5 days on V8A were inoculated on the wounds. The inoculated plants were cultivated in a growth chamber at 30℃ and 70% relative humidity with a 12-h photoperiod. The infected peanut plants exhibited wilt symptoms 11 days after inoculation, consistent with the initial observation, while uninoculated plants remained healthy. To satisfy Koch's postulates, white mycelia were re-isolated from the stems of inoculated plants and axenically cultured in V8A. The morphologies and ITS sequences of the re-isolates were consistent with those of YJ1-2. P. myriotylum has been reported as a causal pathogen of peanut pod rot in the United States and China. However, to the best of our knowledge, this is the first report of wilt disease in peanut plants caused by P. myriotylum in Korea. To prevent the incidence of wilt disease, we will continue our investigations to develop control strategies, including the selection of appropriate agrochemicals.

Investigating Variability in Viral Presence and Abundance across Soybean Seed Development Stages Using Transcriptome Analysis.

Plant transcriptomes offer a valuable resource for studying viral communities (viromes). In this study, we explore how plant transcriptome data can be applied to virome research. We analyzed 40 soybean transcriptomes across different growth stages and identified six viruses: broad bean wilt virus 2 (BBWV2), brassica yellow virus (BrYV), beet western yellow virus (BWYV), cucumber mosaic virus (CMV), milk vetch dwarf virus (MDV), and soybean mosaic virus (SMV). SMV was the predominant virus in both Glycine max (GM) and Glycine soja (GS) cultivars. Our analysis confirmed its abundance in both, while BBWV2 and CMV were more prevalent in GS than GM. The viral proportions varied across developmental stages, peaking in open flowers. Comparing viral abundance measured by viral reads and fragments per kilobase of transcript per million (FPKM) values revealed insights. SMV showed similar FPKM values in GM and GS, but BBWV2 and CMV displayed higher FPKM proportions in GS. Notably, the differences in viral abundance between GM and GS were generally insignificant based on the FPKM values across developmental stages, except for the apical bud stage in four GM cultivars. We also detected MDV, a multi-segmented virus, in two GM samples, with variable proportions of its segments. In conclusion, our study demonstrates the potential of plant transcriptomes for virome research, highlighting their strengths and limitations.

Starch Structure of Raw Materials with Different Amylose Contents and the Brewing Quality Characteristics of Korean Rice Beer.

This study aimed to explore suitable processing materials for rice beer (RB) production by analyzing the starch structure of the raw materials utilized for brewing beer and the quality characteristics of RB. We used malt, employing the Heugho cultivar as the main ingredient, and produced beer containing 30% rice. The regular amylose-containing cultivars Samgwang (SA) and Hangaru (HA) and the high-amylose-containing cultivar Dodamssal (DO) were used as adjuncts. Distribution of the short molecular chains of the starch amylopectin was the highest for SA and malt at 29.3% and 27.1%, respectively. Glucose content was the highest in the wort prepared with 100% malt and 30% SA + 70% malt. The alcohol content in SA RB and HA RB was higher than that in beer prepared with 100% malt. DO RB had the least bitterness and volatile components, such as acetaldehyde and ethyl acetate. The three rice cultivars tested in this study are suitable as starch adjuncts for RB production. The characteristics of RBs varied depending on the molecular structure of the ingredients, irrespective of their amylose contents. SA could be considered a craft beer with quality characteristics and rich flavor components, similar to 100% malt beer, compared to other RBs.

Effects of Consuming Heat-Treated Dodamssal Brown Rice Containing Resistant Starch on Glucose Metabolism in Humans.

Rice is a major source of carbohydrates. Resistant starch (RS) is digested in the human small intestine but fermented in the large intestine. This study investigated the effect of consuming heat-treated and powdered brown rice cultivars 'Dodamssal' (HBD) and 'Ilmi' (HBI), with relatively high and less than 1% RS content, respectively, on the regulation of glucose metabolism in humans. Clinical trial meals were prepared by adding ~80% HBI or HBD powder to HBI and HBD meals, respectively. There was no statistical difference for protein, dietary fiber, and carbohydrate content, but the median particle diameter was significantly lower in HBI meals than in HBD meals. The RS content of HBD meals was 11.4 ± 0.1%, and the HBD meals also exhibited a low expected glycemic index. In a human clinical trial enrolling 36 obese participants, the homeostasis model assessment for insulin resistance decreased by 0.05 ± 0.14% and 1.5 ± 1.40% after 2 weeks (p = 0.021) in participants in the HBI and HBD groups, respectively. The advanced glycation end-product increased by 0.14 ± 0.18% in the HBI group and decreased by 0.06 ± 0.14% in the HBD group (p = 0.003). In conclusion, RS supplementation for 2 weeks appears to have a beneficial effect on glycemic control in obese participants.

Identification of a Major Locus for Lodging Resistance to Typhoons Using QTL Analysis in Rice.

We detected a new target quantitative trait locus (QTL) for lodging resistance in rice by analyzing lodging resistance to typhoons (Maysak and Haishen) using a scale from 0 (no prostrating) to 1 (little prostrating or prostrating) to record the resistance score in a Cheongcheong/Nagdong double haploid rice population. Five quantitative trait loci for lodging resistance to typhoons were detected. Among them, qTyM6 and qTyH6 exhibited crucial effects of locus RM3343-RM20318 on chromosome 6, which overlaps with our previous rice lodging studies for the loci qPSLSA6-2, qPSLSB6-5, and qLTI6-2. Within the target locus RM3343-RM20318, 12 related genes belonging to the cytochrome P450 protein family were screened through annotation. Os06g0599200 (OsTyM/Hq6) was selected for further analysis. We observed that the culm and panicle lengths were positively correlated with lodging resistance to typhoons. However, the yield was negatively correlated with lodging resistance to typhoons. The findings of this study improve an understanding of rice breeding, particularly the culm length, early maturing, and heavy panicle varieties, and the mechanisms by which the plant's architecture can resist natural disasters such as typhoons to ensure food safety. These results also provide the insight that lodging resistance in rice may be associated with major traits such as panicle length, culm length, tiller number, and heading date, and thereby improvements in these traits can increase lodging resistance to typhoons. Moreover, rice breeding should focus on maintaining suitable varieties that can withstand the adverse effects of climate change in the future and provide better food security.

Outbreak of Rice Panicle Blast in Jeonbuk Province of Korea in 2021.

Rice panicle blast is one of the most serious diseases threatening stable rice production by causing severe damage to rice yields and quality. The disease is easy to occur under low air temperature and frequent heavy rainfall during the heading season of rice. In 2021, a rice panicle blast severely occurred in the Jeonbuk province of Korea. The incidence area of panicle blast accounted for 27.7% of the rice cultivation area of Jeonbuk province in 2021, which was 13.7-times higher than in 2019 and 2.6-times higher than in 2020. This study evaluated the incidence areas of rice panicle blast in each region of Jeonbuk province in 2021. The weather conditions during the heading season of rice, mainly cultivated rice cultivars, and the race diversity of the Jeonbuk isolates were also investigated. It will provide important information for the effective control of the rice panicle blast.

Phylogenetic and Phylodynamic Analyses of Soybean Mosaic Virus Using 305 Coat Protein Gene Sequences.

Soybean mosaic virus (SMV) of the family Potyviridae is the most devastating virus that infects soybean plants. In this study, we obtained 83 SMV coat protein (CP) sequences from seven provinces in Korea using RT-PCR and Sanger sequencing. Phylogenetic and haplotype analyses revealed eight groups of 83 SMV isolates and a network of 50 SMV haplotypes in Korea. The phylogenetic tree using 305 SMV CP sequences available worldwide revealed 12 clades that were further divided into two groups according to the plant hosts. Recombination rarely occurred in the CP sequences, while negative selection was dominant in the SMV CP sequences. Genetic diversity analyses revealed that plant species had a greater impact on the genetic diversity of SMV CP sequences than geographical origin or location. SMV isolates identified from Pinellia species in China showed the highest genetic diversity. Phylodynamic analysis showed that the SMV isolates between the two Pinellia species diverged in the year 1248. Since the divergence of the first SMV isolate from Glycine max in 1486, major clades for SMV isolates infecting Glycine species seem to have diverged from 1791 to 1886. Taken together, we provide a comprehensive overview of the genetic diversity and divergence of SMV CP sequences.

The cooking method features controlling eating quality of cooked rice: An explanation from the view of starch structure in leachate and morphological characteristics.

This study investigated leachate and morphological properties of electric-cooked rice (ECR), electric pressure-cooked rice (EPCR), and instant cooked rice (ICR) to explore the effects of cooking methods on eating quality of cooked rice. The leachate was obtained by rinsing cooked rice with warm water. EPCR had the highest amounts of total solid and amylopectin in the leachate and the highest contents of surface and bound lipid. The amylopectin branch chain length of leachate was not significantly different among rice samples. EPCR leachate solution showed the highest apparent viscosity and the greatest decline with increasing shear rate due to high amount of amylopectin. In morphological characteristics, degrees for disruption of the starch structure and compression of protein present in rice kernel were largest in EPCR. Textural hardness of ICR was much lower than that of ECR or EPCR. EPCR had the highest glossiness, stickiness, moistness, and overall acceptability scores. Principal component analysis score plot showed significant differences in leachate and textural characteristics of cooked rice according to cooking methods.

Enhancing Resistant Starch Content of High Amylose Rice Starch through Heat-Moisture Treatment for Industrial Application.

The objective of the present study is to enhance the resistant starch (RS) content of high amylose rice starch with heat-moisture treatment (HMT) for industrial application. The optimized HMT condition for achieving the highest RS content established using response surface methodology (RSM) was a temperature of 100 °C, moisture content of 24.2%, and a time of 11.5 h. Upon HMT, the RS content increased from 32.1% for native starch to 46.4% in HMT starch with optimized condition. HMT of the starches reduced the solubility and swelling power. The surface of HMT starch granules was more irregular than native starch. The X-ray diffraction (XRD) peak intensity at 2θ = 5° was greatly reduced by HMT, and the peaks at 22.7° and 24.2° were merged. HMT increased the gelatinization temperature and reduced the gelatinization enthalpy. HMT provides a method for the production of high-yield RS2 with high amylose rice starch in industrial application.

Complete Genome Sequence of a Novel Monopartite Mastrevirus, Soybean Geminivirus B, Isolated from Soybean (Glycine max (L.) Merrill).

Soybean is one of the most important crops in Korea. To identify the viruses infecting soybean, we conducted RNA sequencing with samples displaying symptoms of viral disease. A contig displaying sequence similarity to the known Geminivirus was identified. A polymerase chain reaction (PCR) using two different pairs of back-to-back primers and rolling circle amplification (RCA) confirmed the complete genome of a novel virus named soybean geminivirus B (SGVB), consisting of a circular monopartite DNA genome measuring 2616 nucleotides (nt) in length. SGVB contains four open reading frames (ORFs) and three intergenic regions (IRs). IR1 includes a nonanucleotide origin of replication in the stem-loop structure. Phylogenetic and BLAST analyses demonstrated that SGVB could be a novel virus belonging to the genus Mastrevirus in the family Geminiviridae. We generated infectious clones for SGVB by adding a copy of the IR1 region of SGVB, comparing the V-ori in addition to the full-length genome of SGVB. Using the infectious clones, we observed chlorosis and leaf curling with a latent infection in the inoculated Nicotiana benthamiana plants, while none of the inoculated soybean plants showed any visible symptoms of disease. This study provides the complete genome sequence and infectious clones of a novel Mastrevirus referred to as SGVB from soybean in Korea.

Outbreak of Rice Blast Disease at Yeoju of Korea in 2020.

Rice blast is the most destructive disease threatening stable rice production in rice-growing areas. Cultivation of disease-resistant rice cultivars is the most effective way to control rice blast disease. However, the rice blast resistance is easy to breakdown within years by blast fungus that continually changes to adapt to new cultivars. Therefore, it is important to continuously monitor the incidence of rice blast disease and race differentiation of rice blast fungus in fields. In 2020, a severe rice blast disease occurred nationwide in Korea. We evaluated the incidence of rice blast disease in Yeoju and compared the weather conditions at the periods of rice blast disease in 2019 and 2020. We investigated the races and avirulence genes of rice blast isolates in Yeoju to identify race diversity and genetic characteristics of the isolates. This study will provide empirical support for rice blast control and the breeding of blast-resistant rice cultivars.

Changes in Suicide Rate and Characteristics According to Age of Suicide Attempters before and after COVID-19.

This study aims to identify age-related suicide-related factors and changes in suicide rate before and after the onset of the COVID-19 pandemic. METHODS: From 2018 to 2020, the patients who presented to the ED of a university hospital with a suicide attempt were classified into adolescents (≤18 years), adults (19-65 years), and elderly (>65 years), and the visits were grouped into before and after COVID-19. RESULTS: There were 853 visits before and 388 visits after COVID-19, and the results showed that the number of adolescent and adult suicide patients increased immediately after the pandemic, but the overall trend did not show a significant difference from before the pandemic. In the adolescents, the ratio of male patients increased, interpersonal and school-related motivations decreased, the poisoning and cutting methods of suicide were more common, and hospitalization admissions increased. Among the elderly, the ratio of female patients increased, the number of single patients and patients without previous psychiatric problems increased, the motives for physical illness and death of people around increased, the falling and hanging methods of suicide were more common, and hospitalization admissions and deaths increased. CONCLUSION: The impact of COVID-19 on suicide rates and suicide-related factors varies by age group. This finding requires different approaches and methods to suicide prevention based on age.

Characterization of Xanthomonas citri pv. glycines Population Genetics and Virulence in a National Survey of Bacterial Pustule Disease in Korea.

Xanthomonas citri pv. glycines (Xcg) is a major pathogen of soybean (Glycine max) in South Korea, despite the availability of soybean varieties with some resistance. We conducted a nationwide survey of the incidence and severity of bacterial pustule caused by Xcg. The percentage of infected fields was 7% to 17% between 2015 and 2017. We characterized the diversity of a nationwide collection of 106 Xcg isolates based on avrBs3 banding patterns. The isolates fell into 11 groups, each represented by a type strain; only two of these were similar to isolates collected from 1999 to 2002. The diversity of Xcg strains increased and the dominant strains changed between 1999 and 2017, with three new type strains comprising 44% of the isolates examined in 2012 to 2017. Pathogenicity tests did not show evidence for a shift in the races or aggressiveness of Xcg strains. Korean soybean cultivars, including the widely-grown Daewon cultivar, were susceptible to the 11 new type strains. The cultivar CNS, which carries the rxp resistance gene, was susceptible to most type strains, including two representing 83% of the Korean Xcg strains. In contrast, Williams 82, which also carries rxp, showed resistance to at least five type strains. Collectively, these results suggest that Williams 82 has resistance loci in addition to rxp. The widespread distribution of Xcg, the high virulence of the current endemic strains, and the low resistance of most Korean soybean cultivars collectively favor widespread disease in Korea in years that are favorable to pustule development.