• The Plant Pathology Journal
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• v.39 no.4
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• pp.384-396
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• 2023

Colletotrichum acutatum species complex is one of the most important groups in the genus Colletotrichum with a high species diversity and a wide range of host plants. C. acutatum and related species have been collected from different plants and locations in Korea and deposited into the Korean Agricultural Culture Collection (KACC), National Institute of Agricultural Sciences since the 1990s. These fungal isolates were previously identified based mainly on morphological characteristics, and a limitation of molecular data was provided. To confirm the identification of species, 64 C. acutatum species complex isolates in KACC were used in this study for DNA sequence analyses of six loci: nuclear ribosomal internal transcribed spacers (ITS), betatubulin 2 (TUB2), histone-3 (HIS3), glyceraldehyde3-phosphate dehydrogenase (GAPDH), chitin synthase 1 (CHS-1), and actin (ACT). The molecular analysis revealed that they were identified in six different species of C. fioriniae (24 isolates), C. nymphaeae (21 isolates), C. scovillei (12 isolates), C. chrysanthemi (three isolates), C. lupini (two isolates), and C. godetiae (one isolate), and a novel species candidate. We compared the hosts of KACC isolates with "The List of Plant Diseases in Korea", previous reports in Korea and global reports and found that 23 combinations between hosts and pathogens could be newly reported in Korea after pathogenicity tests, and 12 of these have not been recorded in the world.

• Mycobiology
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• v.46 no.2
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• pp.92-100
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• 2018

The filamentous Ascomycota Colletotrichum gloeosporioides sensu lato is a fungus that has been reported worldwide as a causal agent of anthracnose disease in avocado and other crops. In Mexico, this species affects fruits from an early stage of development in the orchard until the post-harvest stage. Although fungicides are continuously applied to control Colletotrichum species, pericarp cankers and soft rot mesocarp in fruits are still frequently observed. Considering the lack of a precise description of the causative agent, the aim of the current study was to determine the pathogens involved in this symptomatology. Twenty-four isolates were consistently obtained from the pericarp of avocado fruits cv. "Hass" collected in the central avocado-producing area of Mexico. Morphological features such as colony growth, conidia size, and mycelial appressorium were assessed. Bayesian multilocus phylogenetic analyses were performed using amplified sequences of the internal transcribed spacer region of the nuclear ribosomal DNA; actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase partial genes; and APn2-Mat1-2 intergenic spacer and mating type Mat1-2 partial gene from the nine selected isolates. In addition, fruits were inoculated with a conidial suspension and reproducible symptoms confirmed the presence of Colletotrichum fructicola in this area. This pathogenic species can now be added to those previously reported in the country, such as C. acutatum, C. boninense, C. godetiae, C. gloeosporioides, and C. karstii. Disease management programs to reduce the incidence of anthracnose should include C. fructicola to determine its response to fungicides that are routinely applied, considering that the appearance of new species is affecting the commercial quality of the fruits and shifting the original population structure.

• The Korean Journal of Mycology
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• v.52 no.1
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• pp.55-60
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• 2024

In August 2023, leaf spot disease was observed in peanuts in Cheongju-si, Korea. Leaf spots occurred at the leaf margins and the lesions gradually expanded. Diseased leaf areas were light or dark brown and irregular in shape. A fungal isolate was obtained from symptomatic leaf and cultured on potato dextrose agar (PDA) medium at 25℃. An isolate was identified as Colletotrichum sojae based on morphological characteristics and sequences of the internal transcribed spacers, glyceraldehyde-3-phosphate dehydrogenase, chitin synthase-1, actin, and 𝛽-tubulin genes. Pathogenicity tests were performed on peanut seedlings in a conidial suspension (1×10⁶ conidia/mL). Lesions were observed on the peanut leaf 5 d after inoculation. The pathogen was re-isolated from the lesions of the inoculated leaves. To the best of our knowledge, this is the first report of anthracnose on peanut caused by C. sojae in Korea.

• Korean journal of applied entomology
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• v.57 no.3
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• pp.165-175
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• 2018

Insects are known to live at wide range of temperature, but can not survive when they are exposed to over $40^{\circ}C$ or below supercooling point. The larvae of Helicoverpa assulta have been reared at high ($35^{\circ}C$), low (3 to $10^{\circ}C$), and room temperature ($25^{\circ}C$; control). To identify stress-related genes, the transcriptomes of fat body have been analyzed. Genes such as cuticular proteins, fatty acyl ${\Delta}9$ desaturase and glycerol 3 phosphate dehydrogenase were up-regulated whereas chitin synthase, catalase, and UDP-glycosyltransferase were down-regulated at low temperature. Superoxide dismutase, metallothionein 2, phosphoenolpyruvate carboxykinase and trehalose transporter have been up-regulated at high temperature. In addition, expressions of heat shock protein and glutathione peroxidase were increased at high temperature, but decreased at low temperature. These temperature-specific expressed genes can be available as markers for climate change of insect pests.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.34-34
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• 2014

Filamentous fungi of the genus Colletotrichum (teleomorph, Glomerella) are considered major plant pathogens worldwide. Cereals, legumes, vegetables, and fruit trees may be seriously affected by this pathogen (1). Colletotrichum species cause typical disease symptoms known as anthracnoses, characterized by sunken necrotic tissue, where orange conidial masses are produced. Anthracnose appears in both developing and mature plant tissues (2). We investigated disease occurrence in apple orchards from 2013 to 2014 in northern Gyeongbuk province, Korea. Typical anthracnose with advanced symptoms was observed in all apple orchards studied. Of late, static fruit spot symptoms are being observed in apple orchards. A small lesion, which does not expand further and remains static until the harvesting season, is observed at the beginning of fruit growth period. In our study, static symptoms, together with the typical symptoms, were observed on apples. The isolated fungus was tested for pathogenicity on cv. 'Fuji apple' (fully ripe fruits, unripe fruits, and cross-section of fruits) by inoculating the fruits with a conidial suspension ($10^5$ conidia/ml). In apple inoculated with typical anthracnose fungus, the anthracnose symptoms progressed, and dark lesions with salmon-colored masses of conidia were observed on fruit, which were also soft and sunken. However, in apple inoculated with fungi causing static symptoms, the size of the spots did not increase. Interestingly, the shape and size of the conidia and the shape of the appressoria of both types of fungi were found to be similar. The conidia of the two types of fungi were straight and cylindrical, with an obtuse apex. The culture and morphological characteristics of the conidia were similar to those of C. gloeosporioides (5). The conidia of C. gloeosporioides germinate and form appressoria in response to chemical signals such as host surface wax and the fruitripening hormone ethylene (3). In this study, the spores started to germinate 4 h after incubation with an ethephon suspension. Then, the germ tubes began to swell, and subsequently, differentiation into appressoria with dark thick walls was completed by 8 h. In advanced symptoms, fungal spores of virtually all the appressoria formed primary hyphae within 16 h. However, in the static-symptom fungus spores, no primary hyphae formed by 16 h. The two types of isolates exhibited different growth rates on medium containing apple pectin, Na polypectate, or glucose as the sole carbon. Static-symptom fungi had a >10% reduction in growth (apple pectin, 14.9%; Na polypectate, 27.7%; glucose, 10.4%). The fungal isolates were also genetically characterized by sequencing. ITS regions of rDNA, chitin synthase 1 (CHS1), actin (ACT), and ${\beta}$-tubulin (${\beta}t$) were amplified from isolates using primer pairs ITS 1 and ITS 4 (4), CHS-79F and CHS-354R, ACT-512F and ACT-783R, and T1 and ${\beta}t2$ (5), respectively. The resulting sequences showed 100% identity with sequences of C. gloeosporioides at KC493156, and the sequence of the ${\beta}$t gene showed 100% identity with C. gloeosporioides at JX009557.1. Therefore, sequence data from the four loci studied proves that the isolated pathogen is C. gloeosporioides. We also performed random amplified polymorphic DNA-PCR, which showed clearly differentiated subgroups of C. gloeosporioides genotypes. The clustering of these groups was highly related to the symptom types of the individual strains.