A New Record and Characterization of Asparagus Purple Spot Caused by Stemphylium vesicarium in Korea

In 2017, small, elliptical, brownish purple spots on spears and ferns of asparagus were found in fields of Gangwon-do. The isolated fungal species was identified as an ascomycete Stemphylium vesicarium based on morphological characteristics and molecular phylogenic analyses including nucleotide sequences of the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and cytochrome b (cytb). A pathogenicity test revealed that S. vesicarium was the causal agent of purple spot disease on asparagus. The occurrence of purple spots caused by S. vesicarium on asparagus is the first report in Korea.

A PAS-Containing Histidine Kinase is Required for Conidiation, Appressorium Formation, and Disease Development in the Rice Blast Fungus, Magnaporthe oryzae

Rice blast disease, caused by the ascomycete fungus Magnaporthe oryzae, is one of the most important diseases in rice production. PAS (period circadian protein, aryl hydrocarbon receptor nuclear translocator protein, single-minded protein) domains are known to be involved in signal transduction pathways, but their functional roles have not been well studied in fungi. In this study, targeted gene deletion was carried out to investigate the functional roles of the PAS-containing gene MoPAS1 (MGG_02665) in M. oryzae. The deletion mutant ΔMopas1 exhibited easily wettable mycelia, reduced conidiation, and defects in appressorium formation and disease development compared to the wild type and complemented transformant. Exogenous cAMP restored appressorium formation in ΔMopas1, but the shape of the restored appressorium was irregular, indicating that MoPAS1 is involved in sensing the hydrophobic surface. To examine the expression and localization of MoPAS1 in M. oryzae during appressorium development and plant infection, we constructed a MoPAS1:GFP fusion construct. MoPAS1:GFP was observed in conidia and germ tubes at 0 and 2 h post-infection (hpi) on hydrophobic cover slips. By 8 hpi, most of the GFP signal was observed in the appressoria. During invasive growth in host cells, MoPAS1:GFP was found to be fully expressed in not only the appressoria but also invasive hyphae, suggesting that MoPAS may contribute to disease development in host cells. These results expand our knowledge of the roles of PAS-containing regulatory genes in the plant-pathogenic fungus M. oryzae.

The Effect of Fungicides on Mycelial Growth and Conidial Germination of the Ginseng Root Rot Fungus, Cylindrocarpon destructans

Ginseng root rot caused by Cylindrocarpon destructans is the most destructive disease of ginseng. Six different fungicides (thiophanate-methyl, benomyl, prochloraz, mancozeb, azoxystrobin, and iprodione) were selected to evaluate the inhibitory effect on the mycelial growth and conidial germination of C. destructans isolates. Benomyl and prochloraz were found to be the most effective fungicides in inhibiting mycelial growth of all tested isolates, showing 64.7% to 100% inhibition at a concentration of 10 µg/mL, whereas thiophanate-methyl was the least effective fungicide, showing less than 50% inhibition even at a higher concentration of 100 µg/mL. The tested fungicides exhibited less than 20% inhibition of conidium germination at concentrations of 0.01, 0.1, and 1 µg/mL. However, the inhibition effect of mancozeb on condium germination of C. destructans was significantly increased to 92% to 99% at a higher concentration of 100 µg/mL, while the others still showed no higher than 30% inhibition.

Antagonistic Evaluation of Chromobacterium sp. JH7 for Biological Control of Ginseng Root Rot Caused by Cylindrocarpon destructans

Cylindrocarpon destructans is an ascomycete soil-borne pathogen that causes ginseng root rot. To identify effective biocontrol agents, we isolated several bacteria from ginseng cultivation soil and evaluated their antifungal activity. Among the isolated bacteria, one isolate (named JH7) was selected for its high antibiotic activity and was further examined for antagonism against fungal pathogens. Strain JH7 was identified as a Chromobacterium sp. using phylogenetic analysis based on 16S rRNA gene sequences. This strain was shown to produce antimicrobial molecules, including chitinases and proteases, but not cellulases. Additionally, the ability of JH7 to produce siderophore and solubilize insoluble phosphate supports its antagonistic and beneficial traits for plant growth. The JH7 strain suppressed the conidiation, conidial germination, and chlamydospore formation of C. destructans. Furthermore, the JH7 strain inhibited other plant pathogenic fungi. Thus, it provides a basis for developing a biocontrol agent for ginseng cultivation.

Inhibition Effects of Silver Nanoparticles against Powdery Mildews on Cucumber and Pumpkin

Powdery mildew is one of the most devastating diseases in cucurbits. Crop yield can decline as the disease severity increases. In this study, we evaluated the effect of silver nanoparticles against powdery mildew under different cultivation conditions in vitro and in vivo . Silver nanoparticles (WA-CV-WA13B) at various concentrations were applied before and after disease outbreak in plants to determine antifungal activities. In the field tests, the application of 100 ppm silver nanoparticles showed the highest inhibition rate for both before and after the outbreak of disease on cucumbers and pumpkins. Also, the application of 100 ppm silver nanoparticles showed maximum inhibition for the growth of fungal hyphae and conidial germination in in vivo tests. Scanning electron microscope results indicated that the silver nanoparticles caused detrimental effects on both mycelial growth and conidial germination.

The Effect of Nano-Silver Liquid against the White Rot of the Green Onion Caused by Sclerotium cepivorum

White rot, which is caused by Sclerotium cepivorum, is a lethal disease affecting green onions. Three different types of nano-silver liquid (WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R) were tested in several different concentrations on three types of media to assess their antifungal activities. Results from in vitro experiments showed that all three of the nano-silver liquids had more than 90% inhibition rates at a concentration of 7 ppm. Greenhouse experiments revealed that all of the nano-silver liquids increased biomass and dry weights, and there were minimal changes in the population of various bacteria and fungi from the soil of greenhouse-cultivated green onions. In addition, a soil chemical analysis showed that there were minimal changes in soil composition.

Kimura's Disease in the Arm / 대한정형외과학회잡지

Kimura's disease is an uncommon, chronic inflammatory disease of unknown etiology. It is an important category of reactive lymphadenopathy in the oriental population. The most common sites are the subcutis of the head and neck, and parotid gland. It's clinical course is benign nature. The treatment modalities for this disease are steroid therapy, radiation therapy and surgical excision. We experienced a case of soft tissue mass in the left arm. It was slightly tender and relatively movable. We excised the mass, which was turned out to be Kimura's disease on microscopic examination.