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.

Genet Variation of Ectomycorrhizal Suillus granulatus Fruiting Bodies in Pinus strobus Stands

The genets of Suillus granulatus in a Pinus strobus stand (13 m × 60 m) were identified using random amplified polymorphic DNA molecular markers and the DNA of mushrooms that fruited for two years, and variations in genet size and distribution were analyzed. From a total of 116 mushrooms, 73 genets were identified and were grouped into three locations. The genets of mushrooms in close proximity differed from each other. The genet sizes varied at any of the three locations. The lengths of the identified genets in the pine stand ranged from 0.09 to 2.90 m. The average number of mushrooms per genet was 1.2 to 2.3, and the percentage of genets that were represented by a single mushroom was 44% to 94%. This variation in the genets of mushrooms in close proximity suggests that the ectomycorrhizal mycelial bodies of S. granulatus propagated sexually by fusing haploid spores derived from the mushrooms gills with below-ground mycelia. Therefore, it is necessary further to investigate the formation of new genets through spores in ectomycorrhizal fungal colonies.

Effects of Aeration of Sawdust Cultivation Bags on Hyphal Growth of Lentinula edodes

The effects of aeration through lid filters on the hyphal growth of Lentinula edodes (oak mushroom) in sawdust cultivation bags were investigated. The aeration treatment levels were traditional 27 mm hole cotton plugs, cotton balls and combinations of seven hole sizes x two hole positions (up and under) in the lids covering plastic bags containing 1.4 kg sawdust medium at 63% moisture that had been autoclaved for one hour and inoculated with sawdust spawn of L. edodes strain 921. Aeration treatment effects were measured based on the CO2 concentration at the 15th wk, as well as the hyphal growth rate and degree of weight loss of bags every 14 days for 15 wk. In bags with traditional cotton plugs, the CO2 concentration was 3.8 +/- 1.3%, daily mean hyphal growth was 2.3 +/- 0.6 mm and daily mean weight loss was 0.84 +/- 0.26 g. In the bags with 15 mm diameter holes, the CO2 concentration was 6.0 +/- 1.6%, daily hyphal growth was 2.8 +/- 0.2 mm and daily weight loss was 0.86 +/- 0.4 g. The bags with 15 mm holes had a higher CO2 concentration and lower water loss than bags with other hole sizes, but the hyphal growth was not significantly different from that of other bags. The weight loss of bags increased proportionally relative to the lid hole sizes. Taken together, these results indicate that traditional cotton plugs are economically efficient, but 15 mm hole lids are the most efficient at maintaining hyphal growth and controlling water loss while allowing CO2 emissions.

Ergosterol and Water Changes in Tricholoma matsutake Soil Colony during the Mushroom Fruiting Season

The purpose of this study is to understand spatio-temporal changes of active fungal biomass and water in Tricholoma matsutake soil colonies during the mushroom fruiting season. The active fungal biomass was estimated by analyzing ergosterol content at four different points within four replicated locations in a single circular T. matsutake colony at Ssanggok valley in the Sogri Mt. National Park in Korea during 2003 to 2005. The four points were the ahead of the colony, the front edge of the colony and 20 cm and 40 cm back from the front edge of the colony. Ergosterol content was 0.0 to 0.7 microg per gram dried soil at the ahead, 2.5 to 4.8 microg at the front edge, 0.5 to 1.8 microg at the 20 cm back and 0.3 to 0.8 microg at the 40 cm back. The ergosterol content was very high at the front edge where the T. matsutake hyphae were most active. However, ergosterol content did not significantly change during the fruiting season, September to October. Soil water contents were lower at the front edge and 20 cm back from the front edge of the colony than at the ahead and 40 cm back during the fruiting season. Soil water content ranged from 12 to 19% at the ahead, 10 to 11% at the edge, 9 to 11% at the 20 cm back and 11 to 15% at the 40 cm back. Our results suggest that the active front edge of the T. matsutake soil colony could be managed in terms of water relation and T. matsutake ectomycorrhizal root development.

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.

Relationship between Water Content and Osmotic Potential of Lentinula edodes

This study was conducted to understand how osmotic potentials in Lentinula edodes tissues are related to water contents and how they change while a mushroom matures. Water content and osmotic potential of L. edodes mushroom tissues from log cultivation and sawdust cultivation were measured and the relationships were analyzed. Osmotic potentials in the tissues were exponentially proportional to their moisture contents and there were strain differences in the potentials. Strain 290 has lower osmotic potential than strain 302, in the tissues at the same water content. As the mushrooms mature, tissue water content maintained ca 94% in head tissues and ca 90% in gills, but significantly decreased from ca 90% to 82% in the stipe tissues. Osmotic potential changes were similar to the tissue water content changes as the mushrooms mature. While osmotic potentials maintained -0.25 to -0.45 MPa in head and gill tissues, the potentials greatly decreased from -0.65 to -1.33MPa in stipe tissues. Our results show that osmotic potentials in L. edodes tissues are exponentially proportional to tissue water contents, that strains differ in osmotic potential related to water, and that stipe tissues can still have nutritional value when they mature.

Amatoxins Poisonings in Korea / 대한간학회지

BACKGROUND/AIMS: From the review of Korean literature most fatal mushroom poisonings have been due to amatoxins with high mortality. So far there have never been investigations on the amatoxins poisonings such as annual incidence, mortality, common causal species, and endemic areas. This study was carried out to develop some basic statistics as part of studies for an effective management of amatoxins intoxications. METHOD: For the year 1999 authors collected cases of mushroom poisonings which had been mainly gathered from hospitals nation-wide. All of the cases with suggestive amatoxins poisonings were screened by symptomatology and laboratory findings. The causal species of mushrooms were identified grossly and microscopically. RESULTS: A total of 54 victims with mushroom poisonings were evaluated. The causal mushroom toxins were diagnosed or strongly suggested as amatoxins in 43 of 54 victims. Eleven of 54 victims did not conform to the category of amatoxins intoxication due to absent or minimal elevation of aminotransferase. Mean age of the victims was 44.3 23.3 (range: 7-78) with male predominance (1.2 : 1). The causal species were confirmed, or strongly suggested, as Amanita virosa in 25 victims, Amanita subjunquillea in 14, and unknown species in 4. Thirty-five out of a total of 43 were regarded as moderate to severe intoxication (AST or ALT >1,000 IU/L) with 20% mortality. Most fatal victims showed marked thrombocytopenia (40,000 19,000/mm3) compared to non-fatal victims (109,066 42,245/mm3). A total of 88.4% of victims was developed in the Kangwon and Kyungpuk provinces. Both are west of the Taebaek Mountains (38/43). CONCLUSIONS: Although the common causal species for amatoxins poisonings in Korea are different from European countries and North America, the mortality is similar to that of those areas. In order to further reduce the mortality, bedside diagnostic methods using biological fluids and more effective therapy for liver failure should be established.