Marasmioid and Gymnopoid Fungi of the Republic of Korea. 8. Gymnopus Section Levipedes

Collections of Gymnopus Section Levipedes from the Republic of Korea have been studied. Two new species, Gymnopus dryophiloides and G. brunneodiscus, are described based on their macro- and micromorphological and phylogenetic characteristics. Three other species, referred to as Gymnopus spp. 1, 2, and 3, are distinguished as separate taxa without formal descriptions. Taxonomic and phylogenetic positions of all taxa have been inferred and confirmed by analyses of ITS and LSU sequence data. Their detailed descriptions, illustrations and an identification key are provided.

Acaulosproa koreana, a New Species of Arbuscular Mycorrhizal Fungi (Glomeromycota) Associated with Roots of Woody Plants in Korea

A new species of arbuscular mycorrhizal fungi (Glomeromycota), Acaulospora koreana, was isolated from forest soils in South Korea. This novel fungus was collected from the rhizosphere of Lindera obtusiloba and Styrax obassia in forest and propagated with Sorghum bicolor in pot. Morphological characteristics of spores of A. koreana are rarely distinguished from Acaulospora mellea, which is reported as one of the most abundant mycorrhizal species in Korea. However, molecular evidence of rDNA sequence using improved primers for glomeromycotan fungal identification strongly supported that A. koreana is different from A. mellea but also any other species belonging to the genus Acaulospora. This is the first novel glomeromycatan fungus introduced in South Korea, but it suggests that there is a high possibility for discovering new arbuscular mycorrhizal fungi considering the abundance of plant species and advanced phylogenetic analysis technique.

Development and Molecular Characterization of Novel Polymorphic Genomic DNA SSR Markers in Lentinula edodes

Sixteen genomic DNA simple sequence repeat (SSR) markers of Lentinula edodes were developed from 205 SSR motifs present in 46.1-Mb long L. edodes genome sequences. The number of alleles ranged from 3–14 and the major allele frequency was distributed from 0.17–0.96. The values of observed and expected heterozygosity ranged from 0.00–0.76 and 0.07–0.90, respectively. The polymorphic information content value ranged from 0.07–0.89. A dendrogram, based on 16 SSR markers clustered by the paired hierarchical clustering' method, showed that 33 shiitake cultivars could be divided into three major groups and successfully identified. These SSR markers will contribute to the efficient breeding of this species by providing diversity in shiitake varieties. Furthermore, the genomic information covered by the markers can provide a valuable resource for genetic linkage map construction, molecular mapping, and marker-assisted selection in the shiitake mushroom.

Community Structures of Arbuscular Mycorrhizal Fungi in Soils and Plant Roots Inhabiting Abandoned Mines of Korea

In this study, we collected rhizosphere soils and root samples from a post-mining area and a natural forest area in Jecheon, Korea. We extracted spores of arbuscular mycorrhizal fungi (AMF) from rhizospheres, and then examined the sequences of 18S rDNA genes of the AMF from the collected roots of plants. We compared the AMF communities in the post-mining area and the natural forest area by sequence analysis of the AMF spores from soils and of the AMF clones from roots. Consequently, we confirmed that the structure of AMF communities varied between the post-mining area and the natural forest area and showed significant relationship with heavy metal contents in soils. These results suggest that heavy metal contamination by mining activity significantly affects the AMF community structure.

Identification of Single Nucleotide Polymorphism Markers in the Laccase Gene of Shiitake Mushrooms (Lentinula edodes)

We identified single nucleotide polymorphism (SNP) markers in the laccase gene to establish a line-diagnostic system for shiitake mushrooms. A total of 89 fungal isolates representing four lines, including Korean registered, Korean wild type, Chinese, and Japanese lines, were analyzed. The results suggest that SNP markers in the laccase gene can be useful for line typing in shiitake mushrooms.

Enhancement of beta-Glucan Content in the Cultivation of Cauliflower Mushroom (Sparassis latifolia) by Elicitation

The effectiveness of three kinds of enzymes (chitinase, beta-glucuronidase, and lysing enzyme complex), employed as elicitors to enhance the beta-glucan content in the sawdust-based cultivation of cauliflower mushroom (Sparassis latifolia), was examined. The elicitors were applied to the cauliflower mushroom after primordium formation, by spraying the enzyme solutions at three different levels on the sawdust-based medium. Mycelial growth was fully accomplished by the treatments, but the metabolic process during the growth of fruiting bodies was affected. The application of a lysing enzyme resulted in an increase in the beta-glucan concentration by up to 31% compared to that of the control. However, the treatment resulted in a decrease in mushroom yield, which necessitated the need to evaluate its economic efficiency. Although we still need to develop a more efficient way for using elicitors to enhance functional metabolites in mushroom cultivation, the results indicate that the elicitation technique can be applied in the cultivation of medicinal/edible mushrooms.

Determination of Glucan Contents in the Fruiting Bodies and Mycelia of Lentinula edodes Cultivars

Shiitake mushrooms (Lentinula edodes) containing beta-glucans may be beneficial for human health; they have been used in the treatment of cancer, hypertension, and high cholesterol levels. The objective of this study was to determine the beta-glucan content in different sections of the fruiting bodies and mycelia of ten shiitake mushroom cultivars. The measured beta-glucan content ranged from 20.06 +/- 1.76% to 44.21 +/- 0.13% in the pileus sections, and from 29.74 +/- 1.40% to 56.47 +/- 4.72% in the stipe sections. The results of this study indicate that the variance in beta-glucan content dependent on the shiitake cultivar, and that the beta-glucan content is higher in the stipe than in the pileus.

Diversity of Arbuscular Mycorrhizal Fungi and Their Roles in Ecosystems

Arbuscular mycorrhizal fungi (AMF) have mutualistic relationships with more than 80% of terrestrial plant species. This symbiotic relationship is ancient and would have had important roles in establishment of plants on land. Despite their abundance and wide range of relationship with plant species, AMF have shown low species diversity. However, molecular studies have suggested that diversity of these fungi may be much higher, and genetic variation of AMF is very high within a species and even within a single spore. Despite low diversity and lack of host specificity, various functions have been associated with plant growth responses to arbuscular mycorrhizal fungal colonization. In addition, different community composition of AMF affects plants differently, and plays a potential role in ecosystem variability and productivity. AMF have high functional diversity because different combinations of host plants and AMF have different effects on the various aspects of symbiosis. Consequently, recent studies have focused on the different functions of AMF according to their genetic resource and their roles in ecosystem functioning. This review summarizes taxonomic, genetic, and functional diversities of AMF and their roles in natural ecosystems.

Spore Dispersion of Tricholoma matsutake at a Pinus densiflora Stand in Korea

The spore of Tricholoma matsutake is considered to be the starting point of the mushroom growth cycle, but the mechanism of mycelial development from the spore stage is not yet clarified. In this study, we tried to measure how far the spores of T. matsutake disperse from a fruiting body located at a Pinus densiflora stand in Korea. We established 16 slide glasses coated with glycerin near a fruiting body in four directions separated by four different distance intervals within a mushroom productive stand after removing all other fruiting bodies from three plots. The number of dispersed spores increased with time from the first day (475 spores/cm2) to the fourth day (836 spores/cm2) after the pileus opened. The number of spores dispersed downward was about 1.5 times greater than that dispersed toward the ridge. The number of dispersed spores decreased exponentially as the distance from each fruiting body increased. More than 95% of the spores dropped within a meter from the fruiting body, with 75% dropping within 0.5 m. Even so, the number of spores dispersed over 5 m from the fruiting body was more than 50 million when considering the total number of spores produced by a fruiting body is about 5 billion.

Ergothioneine Contents in Fruiting Bodies and Their Enhancement in Mycelial Cultures by the Addition of Methionine

The levels of ergothioneine (ERG), which have been shown to act as an excellent antioxidant, were determined in both fruiting bodies and mycelia of various mushroom species. We found that ERG accumulated at different levels in fruiting bodies of mushrooms and showed up to a 92.3-fold difference between mushrooms. We also found that ERG accumulated at higher levels in mycelia than in fruiting bodies of economically important mushroom species such as Ganoderma neo-japonicum, G. applanatum and Paecilomyces tenuipes. The addition of 2 mM methionine (Met) to mycelial culture medium increased the ERG contents in most mushroom species tested, indicating that Met is a good additive to enhance the ERG levels in a variety of mushroom species. Taking these results into consideration, we suggest that the addition of Met to the mycelial culture medium is an efficient way to enhance the antioxidant properties in economically important mushroom species.

Introduction to Distribution and Ecology of Sterile Conks of Inonotus obliquus

Inonotus obliquus is a fungus that causes white heart rot on several broad-leaved species. This fungus forms typical charcoal-black, sterile conks (chaga) or cinder conks on infected stems of the birche (Betula spp). The dark brown pulp of the sterile conk is formed by a pure mycelial mass of fungus. Chaga are a folk remedy in Russia, reflecting the circumboreal distribution of I. obliquus in boreal forest ecosystems on Betula spp. and in meridional mountain forests on beech (Fagus spp.) in Russia, Scandinavia, Central Europe, and Eastern Europe. Distribution at lower latitudes in Western and Southern Europe, Northern America, Asia, Japan, and Korea is rare. Infected trees grow for many years without several symptoms of decline. The infection can penetrate through stem injuries with exterior sterile conks developing later. In the Czech Republic, cinder conk is found on birches inhabiting peat bogs and in mountain areas with a colder and more humid climate, although it is widespread in other broad leaved species over the Czech Republic. The most common hosts are B. pendula, B. pubescens, B. carpatica, and F. sylvatica. Less frequent hosts include Acer campestre, Acer pseudoplatanus, Alnus glutinosa, Alnus incana, Fraxinus excelsior, Quercus cerris, Q. petraea, Q. robur, Q. delachampii, and Ulmus sp.

Effect of Chitosan Acetate on Bacteria Occurring on Neungee Mushrooms, Sarcodon aspratus

Minimal growth inhibitory concentrations (MICs) of chitosan acetate (M.W. 60 kDa) on heterotrophic bacteria (strains MK1, S, and R) isolated from the soft-rotten tissues of Neungee mushroom (Sarcodon aspratus) were measured. The slimy substance produced by the MK1 strain was responsible for the diseased mushroom's appearance. The S and R strains were members of the Burkholderia cepacia complex. These strains showed different levels of susceptibility toward chitosan acetate. The MIC of chitosan acetate against the MK1 and S strains was 0.06%. The MIC against the R strain was greater than 0.10%. Survival fractions of the MK1 and S strains at the MIC were 3 x 10(-4) and 1.4 x 10(-3) after 24 h, and 2 x 10(-4) and 7 x 10(-4) after 48 h, respectively. Survival fractions of the R strain after 24 and 48 hr at 0.1% chitosan acetate were 1 x 10-2 and 6.9 x 10(-3), respectively. Compared to the MK1 and S strains, the low susceptibility of the R stain towards chitosan acetate could be due to the ability of the R strain to utilize chitosan as a carbon source. Thirty-eight percent of Neungee pieces treated in a 0.06% chitosan acetate solution for 2~3 second did not show any bacterial growth at 4 days, whereas bacterial growth around untreated mushroom pieces occurred within 2 days. These data suggest that chitosan acetate is highly effective in controlling growth of indigenous microorganisms on Neungee. The scanning electron micrographs of the MK1 strain treated with chitosan revealed a higher degree of disintegrated and distorted cellular structures.

Breeding and Screening of Lentinula edodes Strains Resistant to Trichoderma spp

Trichoderma spp. cause large crop losses of the cultivated shiitake mushroom, Lentinula edodes. We bred several shiitake strains that are resistant to Trichoderma spp. using di-mon mating to establish a useful method for controlling the greenmold disease. We examined the competitive ability of L. edodes against Trichoderma spp. using a dual culture system to select resistant strains. By screening Trichoderma-resistant strains, we found that among 11 parental strains, 4 strains, including KFRI 36, were confirmed resistant strains. They showed especially strong resistance to T. harzianum, which formed deadlock after mycelial contact and then invaded into the territory of T. harzianum. KFRI 171 also showed resistance to T. atroviride strains. Among 13 strains, which were made by hybridization of shiitake strains, 5 were confirmed to be resistant to Trichoderma, including KFRI 58-1. Their resistance was not correlated to the resistant activity of their parents' strains. Two strains lose resistance and two strains acquire resistance compared to their parents' strains. In SEM observation, the mycelium of L. edodes at the interaction zone of Lentinula-Trichoderma was rugged and swollen by T. harzianum.

Seed Germination of Gastrodia elata Using Symbiotic Fungi, Mycena osmundicola

The germination rate and longevity of seeds of Gastrodia elata Blume have been observed for 48 weeks using Mycena osmundicola strain H-21, one of fungi stimulating seed germination. Storage condition of post-harvest seeds was observed in the different temperature ranges of -30degrees C, -5degrees C, 5degrees C and 30degrees C for 48 weeks. After storage period of 48 weeks, the germination rate of G. elata was 65.7% at 5degrees C and 71.6% at -5degrees C, respectively. Although the germination rate of G. elata was 77.3% for 11 weeks at 25degrees C, the germination rate had been decreased gradually to 49.3% at 13 weeks, 0.3% at 23 weeks and then 0% at 25 weeks. The germination rate was reached to the level of 10% for 2 weeks at -30degrees C and then decreased to 0%.

A Note on Ileodictyon gracile(Clathraceae) in Korea

During the study of mushroom flora in Hongneung Arboretum, Ileodictyon gracile was confirmed as new to Korea and described based on morphological and microscopic characteristics in here. This species has subhypogeous, clathrate structure, and obovoid spores. The clathrate structures have 4~12 polygonal meshes.

Diversity of Arbuscular Mycorrhizal Fungi in Paekryung and Daecheong Islands

Twenty species representing five genera of arbuscular mycorrhizal fungi were isolated from twenty-four soil samples of the rhizosphere of the family Gramineae in Paekryung and Daecheong islands. A few species such as Glomus invermaius, G. marcrocapus var. marcrocarpus and Scutellospora coralloidea were recorded for the first time in Korea. The number of spores per 10g of soil was in the range of 8~337 in Paekryung and 16~349 in Daecheong island, respectively. The number of species per 10g of soil was 2~8 species in Paekryung and 2~7 species in Daecheong, respectively. Among them, G. macrocarpus var. macrocarpus was the most abundant species in both islands. The species diversity and evenness were almost similar in Paekryung and Daecheong Islands. Based on the host plants in two islands, the species diversity showed the highest value of 1.63 in Ischaemum crassipes, whereas the eveuness of species showed the lowest value of 0.35 in Eragrostis ferraginea.