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In September 2020, typical anthracnose symptoms were observed on cotton (Gossypium indicum Lam.) leaves growing in Hahoe village, Andong, Gyeongbuk Province, Korea. The leaves of the infected plant...

Severe disease with leaf spots and necrotic symptoms were observed in Adenophora triphylla var. japonica (Regel) Hara (A. triphylla) during the survey in July 2020 on a field in Andong, Gyeongbuk province, Korea. It is a highly valued medicinal plant used to treat various diseases, including cough, cancer, and obesity. The infected plants initially showed spots with halo lesions, at later stages, enlarged and spread to the leaves, which the lesions becoming yellowing and chlorotic (Fig. 1). In some areas, disease incidence was up to 15% of the plants. The symptomatic samples were collected from A. triphylla and cut into 4 to 5 mm squares, surface-sterilized in 1% sodium hypochlorite for 1 min, rinsed three times, and macerated in sterile distilled water (SDW). They were spread onto nutrient agar (NA) plates and incubated at 28°C for 3 days. The representative bacterial strains selected for identification showed fluorescent colonies on King's medium B (KB). Fifteen isolates from independent samples were subjected to biochemical and pathogenicity tests. The isolates induced a hypersensitive reaction in tobacco leaves, gave a reaction in the anaerobe respiratory test, and were negative for levan, oxidase, arginine dihydrolase, gelatin hydrolysis, aesculin hydrolysis, and starch hydrolysis. The isolated strains presented the following LOPAT profile: - - + - +. The Biolog GN2 microplate and the Release 4.20 system putatively found the isolate to exhibit 93% similarity with the bacterium, Pseudomonas viridiflava. Likewise, analysis of FAME profiles using the Microbial identification system (Sherlock version 3.1) also characterized the representative bacterial strain as P. viridiflava with 87% similarity. The genomic DNA of the isolate was extracted, and the 16S rDNA sequence was amplified with a universal bacterial primer set (27F and 1492R). The sequence was submitted to GenBank under the accession number MT975233. BLASTn analysis yielded 99.79% identity with P. viridiflava strain RT228.1b (accession no. AY604846.1) and 99.72% similarity with P. viridiflava KNOX249.1b strain (accession no. AY604848.1). Phylogenetic dendrogram constructed from the comparative analysis of 16S rDNA gene sequences showing the relationship between P. viridiflava GYUN274 and related Pseudomonas species (Fig. 2). Pathogenicity tests were conducted three times on seedling of A. triphylla by spraying 50 ml of bacterial suspensions of a 24-h culture in KB medium (108 CFU/ml). The leaves inoculated with SDW alone did not develop symptoms; however, the plants treated with isolated bacterial suspensions developed halo and blight symptoms similar to those observed in the field 7 days post-inoculation. Finally, Koch's postulates were verified by re-isolating P. viridiflava from all symptomatic tissues and determined to be morphologically identical to the original isolates. To our knowledge, this is the first report of leaf blight disease of A. triphylla caused by P. viridiflava in Korea. Based on the observed symptoms, and identification by morphological characteristics, molecular data, and pathogenicity against the host plant, the proper control measures can be identified in future studies.

Norovirus is one of the major causes of non-bacterial gastroenteritis in humans. The aim of this study was to analyze the amino acid variation of open reading frame 2 of GII.4 variants in South Korea during the period from November 2006 to December 2012. Sixty-nine complete nucleotide sequences of open reading frame 2 were obtained from 113 GII.4 strains. The GII.4 2006b variants were detected predominantly between 2006 and 2009; however, new GII.4 variants, which were termed the 2010 variant and the 2012 variant, emerged in 2010 and 2012, respectively. The number of GII.4 2006b variants steadily decreased until 2012, whereas the number of gastroenteritis cases caused by the new variants increased between 2010 and 2012. The amino acid sequence in the ORF2 region obtained in this study was compared with other GII.4 variants isolated in various countries. Amino acid variations were observed primarily at epitope sites and the surrounding regions. Amino acids 294, 359, 393, and 413 of the P2 subdomain were the most variable sites among the GII.4 variants. The information in this study can be useful in basic research to predict the emergence and determine the genetic functions of new GII.4 variants.