Eung-Jun Park

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

Abstract 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.

Plant hormone-assisted early family selection in Pinus densiflora via a retrospective approach

In an even-aged pine forest trees can vary considerably in stem size. We examined the basis for this anomaly using a retrospective approach. Twelve open-pollinated families of Pinus densiflora Sieb. et Zucc. were deliberately chosen for their variation in stem volumes at age 32 years. Seedlings obtained from these families were grown to age 6 months under optimal nursery conditions. Endogenous levels of growth hormones (auxin [IAA] and gibberellins [GAs]) and expression of the GA biosynthesis gene, PdGA20ox1, all assessed at age 3 months, were significantly correlated, across family, with seedling stem and/or shoot dry biomass at age 6 months. Retrospective comparisons of seedling growth, seedling stem tissue GA(20) and seedling stem expression levels of PdGA20ox1 were then made, across family, with tree stem growth at age 32 years. Age 6 months length and shoot dry biomass at age 6 months showed positive and significant Pearsons correlations with age 32 years tree stem diameters and a tree stem volume index, as did seedling stem tissue GA(20). Even seedling stem PdGA20ox1 expression levels were positively and near significantly (P = 0.088) correlated with age 32 years tree stem diameters. Auxin and GAs control nursery growth of seedlings at the family level, and this control also extends, for GAs at least, to field growth of older trees. We propose that family differences in PdGA20ox1 gene expression, and thus endogenous GA levels, may explain much of the natural variation seen for tree stem size in even-aged pine forests. If our hypothesis is correct, then the heritable components of variation in tree stem growth capacity should be predictable by hormonal and gene expression profiling. Such profiling, combined with the measurement of seedling phenotypic growth characters, could have the potential to accelerate the early selection of those conifer families that possess traits for inherently rapid stem wood growth.

Overexpression of PtrMYB119, a R2R3-MYB transcription factor from Populus trichocarpa, promotes anthocyanin production in hybrid poplar

Anthocyanins are a group of colorful and bioactive natural pigments with important physiological and ecological functions in plants. We found an MYB transcription factor (PtrMYB119) from Populus trichocarpa that positively regulates anthocyanin production when expressed under the control of the CaMV 35S promoter in transgenic Arabidopsis Amino acid sequence analysis revealed that PtrMYB119 is highly homologous to Arabidopsis PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT1), a well-known transcriptional activator of anthocyanin biosynthesis. Independently produced transgenic poplars overexpressing PtrMYB119 or PtrMYB120 (a paralogous gene to PtrMYB119) (i.e., 35S::PtrMYB119 and 35S::PtrMYB120, respectively) showed elevated accumulation of anthocyanins in the whole plants, including leaf, stem and even root tissues. Using a reverse-phase high-performance liquid chromatography, we confirmed that the majority of the accumulated anthocyanin in our transgenic poplar is cyanidin-3-O-glucoside. Gene expression analyses revealed that most of the genes involved in the anthocyanin biosynthetic pathway were highly upregulated in 35S::PtrMYB119 poplars compared with the nontransformed control poplar. Among these genes, expression of PtrCHS1 (Chalcone Synthase1) and PtrANS2 (Anthocyanin Synthase2), which catalyze the initial and last steps of anthocyanin biosynthesis, respectively, was upregulated by up to 350-fold. Subsequent transient activation assays confirmed that PtrMYB119 activated the transcription of both PtrCHS1 and PtrANS2 Interestingly, expression of MYB182, a repressor of both anthocyanin and proanthocyanidin (PA) biosynthesis, was largely suppressed in 35S::PtrMYB119 poplars, while expression of MYB134, an activator of PA biosynthesis, was not changed significantly. More interestingly, high-level accumulation of anthocyanins in 35S::PtrMYB119 poplars did not have an adverse effect on plant growth. Taken together, our results demonstrate that PtrMYB119 and PtrMYB120 function as transcriptional activators of anthocyanin accumulation in both Arabidopsis and poplar.

Quantitative effects of various tree species on tuber growth and pharmacological compositions of Gastrodia elata

Gastrodia elata is a myco-heterotrophic orchid that has been used in traditional medicine to treat number of human illnesses. It establishes symbiotic associations with compatible mycorrhizal fungi, such as Mycena species and Armillaria mellea, depending on its developmental stages. G. elata tubers contain two major pharmacological substances; gastrodin (GA) and ergothioneine (ERG). Here we investigated whether the use of different tree species could enhance the growth of G. elata tubers, or of the content of GA or ERG. A. mellea infected all 30 tree species but its infection levels varied among species. However, only 14 species stimulated the growth of G. elata immature tubers; Ulmus davidiana produced the biggest tubers (7.8 g FW) while Abies holophylla generated the least significant changes on the growth of tubers reaching their weights to 0.9 g. In contrast to the tuber growth, the infection levels of A. mellea in those trees were similar, indicating that the colonized levels of A. mellea on different tree hosts were not correlated with the yield of G. elata tubers. Interestingly, the weights of immature tubers developed on 14 tree species were negatively correlated with the levels of ERG, but not with those of GA. In conclusion, our study suggested that the use of U. davidiana instead of Quercus species, which has been used for traditional cultivation of G. elata, might enhance the yields of G. elata tubers, but reduce the ERG levels while maintaining the GA levels.

Gain-of-function mutation of AtDICE1, encoding a putative endoplasmic reticulum-localized membrane protein, causes defects in anisotropic cell elongation by disturbing cell wall integrity in Arabidopsis

Background and Aims Anisotropic cell elongation depends on cell wall relaxation and cellulose microfibril arrangement. The aim of this study was to characterize the molecular function of AtDICE1 encoding a novel transmembrane protein involved in anisotropic cell elongation in Arabidopsis. Methods Phenotypic characterizations of transgenic Arabidopsis plants mis-regulating AtDICE1 expression with different pharmacological treatments were made, and biochemical, cell biological and transcriptome analyses were performed. Key Results Upregulation of AtDICE1 in Arabidopsis (35S::AtDICE1) resulted in severe dwarfism, probably caused by defects in anisotropic cell elongation. Epidermal cell swelling was evident in all tissues, and abnormal secondary wall thickenings were observed in pith cells of stems. These phenotypes were reproduced not only by inducible expression of AtDICE1 but also by overexpression of its poplar homologue in Arabidopsis. RNA interference suppression lines of AtDICE1 resulted in no observable phenotypic changes. Interestingly, wild-type plants treated with isoxaben, a cellulose biosynthesis inhibitor, phenocopied the 35S::AtDICE1 plants, suggesting that cellulose biosynthesis was compromised in the 35S::AtDICE1 plants. Indeed, disturbed cortical microtubule arrangements in 35S::AtDICE1/GFP-TuA6 plants were observed, and the cellulose content was significantly reduced in 35S::AtDICE1 plants. A promoter::GUS analysis showed that AtDICE1 is mainly expressed in vascular tissue, and transient expression of GFP:AtDICE1 in tobacco suggests that AtDICE1 is probably localized in the endoplasmic reticulum (ER). In addition, the external N-terminal conserved domain of AtDICE1 was found to be necessary for AtDICE1 function. Whole transcriptome analyses of 35S::AtDICE1 revealed that many genes involved in cell wall modification and stress/defence responses were mis-regulated. Conclusions AtDICE1, a novel ER-localized transmembrane protein, may contribute to anisotropic cell elongation in the formation of vascular tissue by affecting cellulose biosynthesis.

The complete mitochondrial genome sequence of Populus davidiana Dode

Abstract This study sequenced the entire mitochondrial genome of Populus davidiana Dode. It was 779,361 bp in length, containing 33 protein-coding genes, 3 rRNA genes and 22 tRNA genes and 1 pseudogene, and its GC content was 44.8%. Phylogenetic analysis was conducted using 6 mitochondrial genomes from the Salicaceae and Euphorbiaceae families, resulting that P. davidiana Dode was closely related to Populus tremula and Populus tremula × Populus alba. These results will provide fundamental data for the evolutionary studies in Populus genus.

Estimation of acorn production capacity using growth characteristics of Quercus acutissima in a clonal seed orchard

Acorn production varies considerably among individual trees, years, and locations, which directly affect oak regeneration and populations of wildlife species. This study was conducted to estimate the acorn production capacities of trees in a clonal seed orchard (CSO) of Quercus acutissima by analyzing the relationship among morphological characteristics of acorns, growth characteristics of trees, and the number of acorns per tree in 9-year-old and 15-year-old trees, respectively. The age of the tree did not affect individual acorn morphological characteristics (weight, length, and width), but increased the mean acorn yield per tree from 1.26 kg at 9-year-old to 2.71 kg at 15-year-old. The number of acorns per tree showed strong positive correlations (P < 0.0001) with both crown width and crown volume of the tree. According to our equation, it was estimated that the management of tree density (to 180 trees per ha) and crown volume (to 78 m3) may have the maximum acorn production per ha. Therefore, our results suggested that optimal management of tree density and crown volume may be very effective in increasing the acorn production in CSO of Q. acutissima, which further provides an important initial step in establishing a governmental policy for seedling supply plans.

Change of amino acids contents of Gastrodia elata Blume with harvest times and seed tuber

Gastrodia elata Blume, an achlorophyllous orchid plant, has been used in traditional medicine and harvests in spring and fall. Here we investigated the quantitative changes of amino acids in G. elata by harvest times and seed tubers. In the results, we found that there was not big difference in contents of total amino acids but the distribution of amino acids differed depending on harvest times. 19% of total amino acids were asparagin and valine, an essential amino acid, occupied 10% within total amino acids in the tubers harvested in October. Among amino acids in the tubers harvested in April, serine occupied 23% and arginine, an essential amino acid, occupied 10% within total amino acids in tuber. Interestingly, the use of sexually propagated seed tubers produced high concentration of total amino acids compared to vegetatively propagated seed tubers. As for sexually propagated seed tubers, essential amino acids contents similar to the tubes harvested in October and nonessential amino acids contents similar to the tubers harvested in April. In this study, we found that amino acids contents in G. elata tubers altered depending on various cultivation practices. Therefore if these results can be applied to food industry, the value of G. elata as a natural food resource will be enhanced to a great extent.

Isolation and characterization of a monodehydroascorbate reductase gene in poplar (Populus alba × P. glandulosa)

Abstract Monodehydroascorbate reductase (MDHAR) is an important enzyme that plays a role in the detoxification of reactive oxygen species (ROS) by maintaining reduced pool of ascorbate through recycling the oxidized form of ascorbate. In this study, we isolated a PagMDHAR1 gene from Populus alba × P. glandulosa , and investigated its expression characteristics. The PagMDHAR1 cDNA encodes a putative 434 amino acids containing FAD- and NAD(P)H-binding domains. Southern blot analysis indicated that a single nuclear gene encodes this enzyme. Northern hybridization analysis revealed that PagMDHAR1 is highly expressed in both suspension cells and flower tissues, while its expression levels were enhanced by drought, salt, cold, wounding and ABA. Therefore, PagMDHAR1 might be expressed in response to abiotic stress through the ABA-mediated signaling pathway in this poplar species, suggesting that the PagMDHAR1 plays an important role in the defense mechanisms against oxidative stress. Keywords

Eeffect of Wood Xylem Flour in Liquid Culture on Mycelial Biomass of Lentinus lepideus and Lentinus edodes

This study was carried out to investigate the promoting effect of wood flour on the mycelial growth of Lentinus lepideus and Lentinus edodes. To determine the optimal culture condition, we first examined the tissue origin of pine flour (Pinus densiflora) including needle, bark, root and xylem. Only the xylem-derived flour increased mycelial growth compared to no treatment control. The addition of the xylem flour (5 g/l) showed the highest increase and the glucose level in the basal medium was best at 10 g/l. The smaller particle size of the xylem flour showed the positive effect on mycelial growth; two-fold increase when supplemented with flour of which particle size is less than in diameter compared to . The addition of the xylem flour continuously increased the mycelial production for 25 days while mycelia stopped growing within 15 days without the xylem flour. In addition, when woody flour obtained from the different tree species was applied to L. edodes mycelial culture, all treatments accelerated mycelial production compared to the control. Based on all results described above, we conclude that the supplementation of woody flour to culture medium may be an another promising way to increase mycelial production of economically important fungi.