Pinus densiflora Siebold et Zucc. is the major green canopy species in the mountainous area of Korea. To assess the response of resin acid biosynthetic genes to mechanical and chemical stimuli, we cloned cDNAs of genes encoding enzymes involved in the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway (1-deoxy-d-xylulose 5-phosphate synthase (PdDXS), 1-deoxy-d-xylulose 5-phosphate reductoisomerase (PdDXR) and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (PdHDR)) by the rapid amplification of cDNA ends (RACE) technique. In addition, we cloned the gene encoding abietadiene synthase (PdABS) as a marker for the site of pine resin biosynthesis. PdHDR and PdDXS occurred as two gene families. In the phylogenetic trees, PdDXSs, PdDXR and PdHDRs each formed a separate clade from their respective angiosperm homologs. PdDXS2, PdHDR2 and PdDXR were most actively transcribed in stem wood, whereas PdABS was specifically transcribed. The abundance of PdDXS2 transcripts in wood in the resting state was generally 50-fold higher than the abundance of PdDXS1 transcripts, and PdHDR2 transcripts were more abundant by an order of magnitude in wood than in other tissues, with the ratio of PdHDR2 to PdHDR1 transcripts in wood being about 1. Application of 1 mM methyl jasmonate (MeJA) selectively enhanced the transcript levels of PdDXS2 and PdHDR2 in wood. The ratios of PdDXS2 to PdDXS1 and PdHDR2 to PdHDR1 reached 900 and 20, respectively, on the second day after MeJA treatment, whereas the transcript level of PdABS increased twofold by 3 days after MeJA treatment. Wounding of the stem differentially enhanced the transcript ratios of PdDXS2 to PdDXS1 and PdHDR2 to PdHDR1 to 300 and 70, respectively. The increase in the transcript levels of the MEP pathway genes in response to wounding was accompanied by two orders of magnitude increase in PdABS transcripts. These observations indicated that resin acid biosynthesis activity, represented by PdABS transcription, was correlated with the selective transcriptions of PdDXS2 and PdHDR2. Introduction of PdDXS2, PdHDR1 and PdHDR2 rescued their respective knockout Escherichia coli mutants, confirming that at least these three genes were functionally active. Intracellular targeting of the green fluorescent protein fused to the N-terminal 100 amino acid residues of these genes in the Arabidopsis transient expression system showed that the proteins were all targeted to the chloroplasts. Our results suggest that the MEP pathway regulates resin biosynthesis in the wood of P. densiflora by differential transcription of the multiple PdDXS and PdHDR genes.

We investigated the diversity and community structure of ectomycorrhizal (EcM) fungi in Pinus thunbergii stands on the eastern coast of Korea. We established two 10 × 10-m plots in six forest stands and sampled soil blocks containing rootlets of mature P. thunbergii trees. EcM roots were classified into morphological groups, and the fungal taxa associated with each morphotype were identified by sequencing the nuclear rDNA internal transcribed spacer region. Cenococcum geophilum and the Atheliales, Clavulinaceae, Russulaceae and Thelephoraceae species were the main members of the EcM fungal community, which included a total of 68 observed fungal taxa. As a whole, the community consisted of a few dominant fungal taxa, such as C. geophilum (28.6% relative abundance), and a large number of rare fungal taxa that showed low abundances and local distributions. Colonization patterns at the local site scale and at the scale of the study plots greatly differed among the EcM fungal taxa; C. geophilum was distributed extensively and was dominant in several study sites, whereas a certain Lactarius sp. was distributed locally but dominated in a given study site. We conclude with a discussion of the relationship between colonization patterns of EcM fungi and soil and environmental conditions.

We isolated a water-soluble extract, PG101, from cultured mycelia of Lentinus lepideus. Treatment of human peripheral blood mononuclear cells (PBMCs) with PG101 increased levels of TNF-α, IL-1β, IL-10, and IL-12 by 100- to 1000-fold, whereas GM-CSF and IL-18 were activated by an order of magnitude. On the contrary, IFN-γ and IL-4 were not affected. The response to PG101 occurred in a dose- and time-dependent manner. From the human PBMCs treated with PG101, TNF-α was a first cytokine to be activated, detectable at 2 hr post-treatment followed by IL-1β at 6 hr post-treatment. IL-12 and IL-10 were the next to follow. GM-CSF and IL-18 both showed significant increases 24 hr after treatment. When PBMCs were sorted into various cell types, monocyte/macrophages, but not T and B cells, were the major target cell type responsive to PG101. Consistent with this result, the profile of cytokine expression upon PG101 treatment was comparable between PBMCs and a human promonocytic cell line (U937), whereas cell lines of T cell and myeloid origins did not respond to PG101. Data from a transient transfection assay involving specific reporter plasmids indicated that cellular transcription factor such as NF-κB, but not AP-1, was highly activated by PG101. Results from a gel retardation assay and the experiment involving a specific NF-κB inhibitor confirmed the involvement of NF-κB. Despite its significant biological effect on various cytokines, PG101 remained nontoxic in both rats and PBMCs even at a biological concentration approximately 20 times greater. PG101 demonstrates great potential as a therapeutic immune modulator.

Two-hundred and fifty-five strains of actinomycetes isolated from soil samples were screened for their antagonistic activities against four well-known wood decay fungi (WDF), including a brown rot fungus, Gloeophyllum trabeum and three white rot fungi Donkioporia expansa, Trametes versicolor, and Schizophyllum commune. A dual culture assay using culture media supplemented with heated or unheated culture filtrates of selected bacterial strains was used for the detection of their antimicrobial activity against four WDF. It was shown that Streptomyces atratus, S. tsukiyonensis, and Streptomyces sp. greatly inhibited the mycelial growth of the WDF tested compared with the control. To evaluate the biocontrol efficacy of S. atratus, S. tsukiyonensis, and Streptomyces sp., wood blocks of Pinus densiflora inoculated with three selected Streptomyces isolates were tested for weight loss, compression strength (perpendicular or parallel to the grain), bending strength, and chemical component changes. Of these three isolates used, Streptomyces sp. exhibited higher inhibitory activity against WDF, especially G. trabeum, as observed in mechanical and chemical change analyses. Scanning electron microscopy showed that cell walls of the wood block treated with Streptomyces strains were thicker and collapsed to a lesser extent than those of the non-treated control. Taken together, our findings indicate that Streptomyces sp. exhibits the potential to be used as a biocontrol agent for wood decay brown rot fungus that causes severe damage to coniferous woods.

PG101 is a water-soluble extract from Lentinus lepideus. It is a potential biological response modifier that activates selective cytokines in vitro, mainly by controlling cellular transcription factor NF-κB. Effects of PG101 were tested on bone marrow cells in irradiated mice. Mice were irradiated with a dose of 6 Gy and were given PG101 by gavages daily for 24 days. In PG101-treated mice, the number of colony-forming cells, including colony-forming units (CFU)-granulocytes/macrophages (GM) and erythroid burst-forming units (BFU-E), were increased to almost the levels seen in nonirradiated control as early as 8 days after irradiation. Two-color flow cytometric analysis using antibodies to ER-MP12 and ER-MP20 suggested that in the bone marrow cell population, PG101 increased the number of granulocytes (ER-MP12^-20^med) and myeloid progenitors (ER-MP12⁺20⁺). Analysis of surface c-Kit and Gr-1 proteins in bone marrow cells indicated that PG101 might induce differentiation of progenitor cells to granulocytes and/or proliferation of the committed cells. Lastly, oral administration of PG101 highly increased serum levels of GM-CSF, IL-6, and IL-1β. Interestingly, the level of TNF-α was elevated by irradiation in control mice, but was maintained at the background level in PG101-treated mice, suggesting that PG101 might effectively suppress TNF-α-related pathologic conditions. Our results strongly suggest the great potential of PG101 as an immune enhancer during radiotherapy and/or chemotherapy.