First Report of Colletotrichum gigasporum causing Anthracnose of chili pepper in South Korea.

Anthracnose, a destructive fungal disease, poses a significant threat to chili pepper (Capsicum annuum L.) production worldwide (de Silva et al. 2019). In South Korea, anthracnose outbreaks have traditionally been attributed to several Colletotrichum species such as C. gloeosporioides and C. acutatum. About 10% of the yield (chili production) is lost annually in South Korea due to chili anthracnose (Oo et al. 2020). During field surveys conducted in August 2017, symptomatic lesions resembling anthracnose were observed on chili pepper in two farmer's fields (Gochang and Cheongyang) in South Korea. Affected fruits exhibited characteristic symptoms, including circular sunken lesions with dark margins and abundant orange spore masses on the surface. About 20% of chili pepper fruit were affected in each field with an area of about 0.2 ha. Five putative Colletotrichum spp. isolates were obtained from six affected fruits (three from each field) following the procedure described by Cai et el. (2009). Three isolates (C01049, C01111, and C01115), representing each location, were selected to identify at the species level. Colonies on potato dextrose agar (incubated at 25°C in the dark for 7 days) were cottony with entire margins, white aerial mycelium and dark gray in the center. Conidia were hyaline, aseptate, cylindrical with bothnds round, and 17.8 - 30.5 × 6.0 -10.0 µm (mean 23.8 ×7.9 µm, n = 30). Appressoria were dark brown, irregular but mostly ovoid with smooth walls. These morphological features align with those of Colletotrichum spp. within the Colletotrichum gigasporum species (Liu et al. 2014). The identity of the pathogen was further confirmed through multi-locus phylogenetic analysis. The target genes including ITS, ACT, CHS-1, GAPDH, TUB2, and GS were amplified and sequenced using the primer sets ITS1/ITS4, ACT 512F/ ACT-783R, CHS-79F/ CHS-345R, GDF/GDR, T1/Bt2b, and GSF1/GSR1, respectively (Weir et al. 2012; Liu et al. 2014). The resulting sequences were deposited in GenBank (accession no: ITS: MT605261, MT605262, LC823714; ACT: MT612991, MT612992, LC823718; CHS-1: MT612993, MT612994, LC823717; GAPDH: LC811375, LC811376, LC823716; TUB2: MT612997, MT612998, LC823715; GS: LC811377, LC811378, LC823719). The constructed Bayesian and maximum likelihood tree based on combined sequences of ITS, ACT, CHS-1, GAPDH, TUB2, and GS confirmed the identification of the isolates (C01049, C01111, C01115) as C. gigasporum. Pathogenicity tests were conducted by inoculating healthy chili fruit with 70 µL of a conidial suspension (1×106 conidia /mL) of pure cultures of the isolates. The conidial suspension was applied on 10 wounded or 10 non-wounded fruit. The same number of fruit were treated with sterile distilled water as controls. Within 5 days of inoculation, symptoms consistent with anthracnose developed on the inoculated wounded fruit, whereas non-wounded and control fruit remained asymptomatic. This experiment was repeated twice. Colletotrichum gigasporum was re-isolated from diseased tissue of inoculated fruit. Colletotrichum gigasporum has been identified as the cause of anthracnose on Dalbergia odorifera, Carica papaya in China, and Brassica oleracea in India (Wan et al., 2018; Saini et al. 2022; He et al. 2023). To the best of our knowledge, this report marks the first documented instance of C. gigasporum causing anthracnose of chili pepper in South Korea. These results indicate that various species of Colletotrichum can be the fungi causing chili pepper anthracnose. The findings of this study emphasize the need for effective disease management strategies to mitigate impact of C. gigasporum on chili pepper cultivation in the region.

First Report of Root and Collar Rot caused by Phytophthora nicotianae on ⨯Graptoveria 'Silver Star' in Korea.

⨯Graptoveria 'Silver Star' (a cross between Graptopetalum filiferum and Echeveria agavoides) from the Crassulaceae family, are an evergreen succulent with lotus constellation-shaped flowers, making it consumer favorite ornamental plant in Korea. In 2019, Korea's ornamental production was estimated at KRW 517.4 billion (EUR 382 million), from 4,244 ha of farming area according to the Ministry of Agriculture, Food and Rural Affairs of Korea. In July 2023, ⨯Graptoveria 'Silver Star' plants with chlorotic leaves, root and collar rot were observed in a greenhouse in Yongin (37°14'27.9"N, 127°10'39.19"E), Korea. To isolate the causal agent, small pieces (1 mm2) of symptomatic tissues were surface-sterilized using 1% NaOCl for 1 min, then put onto a water agar (WA) plate and incubated in the dark at 25℃ for five days. Two isolates (FD00202, FD00203) were obtained from diseased leaves, stem and roots by isolating single sporangium. To investigate the morphological characteristics of the isolates, the mycelium from potato dextrose agar (PDA) were transferred to V8 agar (V8A) followed by incubation at 25°C in the dark for 7 days. The isolates produced dense cottony mycelium, with slightly petaloid and light rossette pattern, with coralloid edges measuring 70 to 83 mm diameter. Sporangium were spheroid (30.0-48.0 µm long, 25.0-35.0 µm wide) with globose chlamydospores (17.0-50.0 µm long, 18.0-38.0 µm wide). Oogonia were not observed. Morphological and cultural characteristics of these isolates were phenotypically similar to that of Phytophthora nicotianae (Faedda et al. 2013; Abad et al. 2023). For molecular identification, genomic DNA was extracted from 5 days old cultures using the Maxwell® RSC PureFood GMO and Authentication Kit (Promega). Two gene regions, the rDNA-ITS, COX I were amplified and sequenced using primers ITS1/ITS4 and FM83/FM84, respectively (White et al. 1990; Martin and Tooley 2003). The resulting sequences were deposited in GenBank with accession no. LC783858 to LC783861. A BLASTn search of the DNA sequences from ITS, COX I showed 99.81 and 98.94% identity to P. nicotianae isolate IMI 398853, respectively. Maximum likelihood phylogenetic analyses were performed for the combined data set with ITS, COX I using MEGA7 under the Tamura-Nei model (Kumar et al. 2016). The isolates formed a monophyletic group with P. nicotianae isolate IMI 398853, CPHST BL162, and CPHST BL 44. Based on morphological characteristics and molecular analysis, the isolates were identified as P. nicotianae. T confirm their pathogenicity, inoculum was prepared in accordance with Ann (2000). Artificially wounded healthy plant roots were dipped in zoospore suspension (3.0 × 106 zoospore/ml) for 24 hours, with mock-treated plants (control) dipped in sterile distilled water (Ann. 2000). Thereafter, the plants were transplanted into new medium and kept under high humidity. Symptoms were observed after 10 days of incubation. The plants inoculated with P. nicotianae showed similar symptoms of chlorotic leaves with root and collar rot, while control remained symptomless. The pathogen was re-isolated from all inoculated plants and confirmed as P. nicotianae by morphological and molecular analysis. but not from controls, fulfilling Koch's postulates. Phytophthora nicotianae was previously report on Echeveria derenbergii and Kalanchoe blossfeldiana causing brown spot on stems and roots in California and Korea, respectively (French 1989; Oh and Son 2008). To best of our knowledge, this is the first report of P. nicotianae causing root and collar rot on ⨯Graptoveria 'Silver Star' plants in the Korea.

Role of cytosolic and endoplasmic reticulum Ca2+ in pancreatic beta-cells: pros and cons.

Pancreatic beta cells utilize Ca2+ to secrete insulin in response to glucose. The glucose-dependent increase in cytosolic Ca2+ concentration ([Ca2+]C) activates a series of insulin secretory machinery in pancreatic beta cells. Therefore, the amount of insulin secreted in response to glucose is determined in a [Ca2+]C-dependent manner, at least within a moderate range. However, the demand for insulin secretion may surpass the capability of beta cells. Abnormal elevation of [Ca2+]C levels beyond the beta-cell endurance capacity can damage them by inducing endoplasmic reticulum (ER) stress and cell death programs such as apoptosis. Therefore, while Ca2+ is essential for the insulin secretory functions of beta cells, it could affect their survival at pathologically higher levels. Because an increase in beta-cell [Ca2+]C is inevitable under certain hazardous conditions, understanding the regulatory mechanism for [Ca2+]C is important. Therefore, this review discusses beta-cell function, survival, ER stress, and apoptosis associated with intracellular and ER Ca2+ homeostasis.

Recombinant Unique Cartilage Matrix-associated Protein Potentiates Osteogenic Differentiation and Mineralization of MC3T3-E1 Cells.

OBJECTIVE: The relative balance of osteoblasts in bone formation and osteoclasts in bone resorption is crucial for maintaining bone health. With age, this balance between osteoblasts and osteoclasts is broken, resulting in bone loss. Anabolic drugs are continuously being developed to counteract this low bone mass. Recombinant proteins are used as biotherapeutics due to being relatively easy to produce on a large scale and are cost-effective through various expression systems. This study aimed to develop a recombinant protein that would positively impact osteoblast differentiation and mineralized nodule formation using unique cartilage matrix-associated protein (UCMA). METHODS: A recombinant glutathione-S-transferase (GST)-UCMA fusion protein was generated in an E.coli system, and purified by affinity chromatography. MC3T3-E1 osteoblast cells and Osterix (Osx)-knockdown stable cells were cultured for 14 days to investigate osteoblast differentiation and nodule formation in the presence of the recombinant GST-UCMA protein. The differentiated cells were assessed by alizarin red S staining and quantitative PCR of the osteoblast differentiation marker osteocalcin. In addition, cell viability in the presence of the recombinant GST-UCMA protein was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell adhesion assay. RESULTS: The isolation of both purified recombinant GST-only and GST-UCMA proteins were confirmed at 26 kDa and 34 kDa, respectively, by Coomassie staining and western blot analysis. Neither dose-dependent nor time-dependent presence of recombinant GST-UCMA affected MC3T3-E1 cell viability. However, MC3T3-E1 cell adhesion to the recombinant GST-UCMA protein increased dose-dependently. Osteoblast differentiation and nodule formation were promoted in both MC3T3-E1 osteoblast cells and Osxknockdown stable cells when cultured in the presence of recombinant GST-UCMA protein. CONCLUSION: A recombinant GST-UCMA protein induces osteogenic differentiation and mineralization, suggesting its potential use as an anabolic drug to increase low bone mass in osteoporotic patients.