Efficacy of Diphenyleneiodonium Chloride (DPIC) Against Diverse Plant Pathogens

Many of the fungicides and antibiotics currently available against plant pathogens are of limited use due to the emergence of resistant strains. In this study, we examined the effects of diphenyleneiodonium chloride (DPIC), an inhibitor of the superoxide producing enzyme NADPH oxidase, against fungal and bacterial plant pathogens. We found that DPIC inhibits fungal spore germination and bacterial cell proliferation. In addition, we demonstrated the potent antibacterial activity of DPIC using rice heads infected with the bacterial pathogen Burkholderia glumae which causes bacterial panicle blight (BPB). We found that treatment with DPIC reduced BPB when applied during the initial flowering stage of the rice heads. These results suggest that DPIC could serve as a new and useful antimicrobial agent in agriculture.

Identification of Genes Related to Fungicide Resistance in Fusarium fujikuroi

We identified two genes related to fungicide resistance in Fusarium fujikuroi through random mutagenesis. Targeted gene deletions showed that survival factor 1 deletion resulted in higher sensitivity to fungicides, while deletion of the gene encoding F-box/WD-repeat protein increased resistance, suggesting that the genes affect fungicide resistance in different ways.

Chlamydospore Induction from Conidia of Cylindrocarpon destructans Isolated from Ginseng in Korea

Cylindrocarpon destructans causes root rot disease in ginseng and can survive for a long time, producing chlamydospores. We optimized conditions to induce chlamydospore production from the conidia of C. destructans, isolated from Korean ginseng. This will provide the basis for testing the efficacy of control agents targeting these chlamydospores.

Microcyle Conidiation in Filamentous Fungi

The typical life cycle of filamentous fungi commonly involves asexual sporulation after vegetative growth in response to environmental factors. The production of asexual spores is critical in the life cycle of most filamentous fungi. Normally, conidia are produced from vegetative hyphae (termed mycelia). However, fungal species subjected to stress conditions exhibit an extremely simplified asexual life cycle, in which the conidia that germinate directly generate further conidia, without forming mycelia. This phenomenon has been termed as microcycle conidiation, and to date has been reported in more than 100 fungal species. In this review, first, we present the morphological properties of fungi during microcycle conidiation, and divide microcycle conidiation into four simple categories, even though fungal species exhibit a wide variety of morphological differences during microcycle conidiogenesis. Second, we describe the factors that influence microcycle conidiation in various fungal species, and present recent genetic studies that have identified the genes responsible for this process. Finally, we discuss the biological meaning and application of microcycle conidiation.

Entomopathogenicity of Simplicillium lanosoniveum Isolated in Korea

Fruiting bodies similar to those of the ascomycete fungi Podostroma cornu-damae and Cordyceps militaris were collected from Mt. Seunghak in Busan, Korea on August 21, 2012. The fruiting bodies were cylindrical, with tapered ends and golden red in color. The fruiting bodies contained abundant conidiophores bearing single-celled conidia, but no perithecia or asci. Pure culture of the fungal isolates was obtained through single-spore isolation. Analyses of morphological characteristics, including conidia shape, and phylogenetic traits, using internal transcribed spacer sequences, showed that these isolates belonged to the species Simplicillium lanosoniveum. Although this fungal species is known to be mycoparasitic, the isolates obtained in this study were unable to infect fungi. However, silkworms (Bombyx mori) inoculated with the fungal isolates died during the larval or pupal stages, as has been shown for the strongly entomopathogenic fungus Beauveria bassiana. This study is the first report of the entomopathogenicity of S. lanosoniveum and indicates its potential for use in biological control of insects.