Dammarane saponins of leaves of Panax pseudo-ginseng subsp. himalaicus

From dried leaves of Panax pseudo-ginseng subsp. himalaicus collected in Eastern Himalaya, new dammarane saponins, named pseudo-ginsenosides-F₁₁ and -F₈ were isolated along with the known Ginseng-root saponins, ginsenosides-Rb₃, Rd and -Re. Pseudo-ginsenoside-F₈ was proved to be a mono-acetyl-ginsenoside-Rb₃ and the location of its acetyl group was established mainly by ¹³C NMR spectroscopy. Pseudo-ginsenoside-F₁₁, was identified as the 6-O-α-rhamnopyransyl(1 → 2)-β-glucopyranoside of 3β,6α,12β,25-tetrahydoxy-(20S,24R)-epoxy-dammarane. The C-24 configuration of ocotillone and its related triterpenes was confirmed to be 24R excluding the recent comment by Lavie et al.     

Discovery of genes for ginsenoside biosynthesis by analysis of ginseng expressed sequence tags

Expressed sequence tags (ESTs) provide a valuable tool that can be used to identify genes in secondary metabolite biosynthesis. Ginseng (Panax ginseng C.A Meyer) is a medicinal plant that accumulates ginsenosides in roots. We sequenced 11,636 ESTs from five ginseng libraries in order to create a gene resource for biosynthesis of ginsenosides, which are thought to be the major active component in roots. Only 59% of the ginseng ESTs exhibited significant homology to previously known polypeptide sequences. Stress- and pathogen-response proteins were most abundant in 4-year-old ginseng roots. ESTs involved in ginsenoside biosynthesis were identified by a keyword search of BLASTX results and a domain search of ginseng ESTs. We identified 4 oxidosqualene cyclase candidates involved in the cyclization reaction of 2,3-oxidosqualene, 9 nine cytochrome P450 and 12 glycosyltransferse candidates, which may be involved in modification of the triterpene backbone.Abbreviations cDNA Complementary DNA - ESTs Expressed sequence tagsCommunicated by I.S. Chung     

Alteration of selection regime resulting from harvest of American ginseng, <Emphasis Type="Italic">Panax quinquefolius</Emphasis>

Replicate harvest simulations were conducted in a large natural population of Panax quinquefolius L.␣(Araliaceae) to determine the selective effects of harvest. We investigated how minimum size requirements and the influence of size on apparency to human harvesters could result in preferential removal of large plants. To determine which plants were encountered in the large population, harvesters were tracked using GPS as they searched for every legally harvestable, adult plant they could find. Plants were assigned stage-specific fitness measures based on their contributions to population growth rate (λ) under three demographically based harvest regimes: no harvest, harvest and harvest removing seeds. Plant size was codified into a size-index equal to the product of total leaf area and stem height. Heterogeneity of slopes was tested to determine if the selection gradients (β) describing the relationship between fitness and size varied among the three harvest regimes. Harvest differentially reduced the fitness of larger plants in one of four individual harvest simulations. The combined harvest simulation significantly altered the selection regime for size in the population of juvenile and adult (harvestable) plants. Seed removal by harvesters intensified fitness declines for larger plants. Because larger plants contribute most to population growth, the selective effects of harvest could result in a shift in the evolutionary dynamics of this species with significant conservation implications.     

Development and characterization of new microsatellite markers for ginseng (<Emphasis Type="Italic">Panax ginseng</Emphasis> C. A. Meyer)

Panax ginseng C.A. Meyer, commonly known as Korean or Asian ginseng, is a perennial herb native to Korea and China. Its roots are highly prized for several medicinal properties. The present study describes development and characterization of twenty-two polymorphic microsatellite markers for this species. A total of 99 alleles were detected with an average of 4.5 alleles per locus across 20 accessions. Values for observed (H _O ) and expected (H _E ) heterozygosities ranged from 0.05 to 1.00 and from 0.18 to 0.73, respectively. Eleven loci deviated from Hardy–Weinberg equilibrium (P < 0.001). Significant (P < 0.05) heterozygote deficiency was observed at 13 loci. Exact test for linkage disequilibrium showed significant values (P < 0.05) between 12 pairs of loci. These microsatellite markers provide powerful tools for understanding population and conservation genetics of this species and also for genetic differentiation and authentication of different Panax species being used in commercial ginseng products.     

三七重茬根际土壤中化感物质的测定及其对三七根腐菌的生长作用

目的 研究三七重茬根际土壤中化感物质的组成及其对病原微生物的化感作用。方法 采用乙酸乙酯提取三七重茬根际土壤中的化感物质,利用GC-MS对萃取液进行物质组成分析,并研究检测中出现的特征性化感物质对羟基苯甲酸、邻苯二甲酸二异丁酯对三七根腐病菌（F.oxysporum Schlecht）的化感作用。结果 采集的三七重茬土壤中共检测到29种化感物质,其中2种特征性化感物质对羟基苯甲酸、邻苯二甲酸二异丁酯对三七病原菌的生长呈现低促高抑的现象,且当对羟基苯甲酸浓度为5 mmol/L时能促进病菌小孢子的产生。结论 检测到的化感物质组分为苯甲酸及其衍生物类、酚类、酯类、饱和烃类等物质。这些物质在低浓度时有利于病原菌的生长,对病害的发生具有促进作用。     

人参原生质体培养再生愈伤组织

人参原生质体培养未见报道成功。Harn(1974)曾用人参幼叶,幼根和上胚轴进行原生质体分离,但得到的数量很少,无法进行培养。本实验以人参培养细胞为材料,通过培养再生了愈伤组织。     

Elicitation of different Panax ginseng transformed root phenotypes for an improved ginsenoside production

We tested the effect of the presence in the culture medium of chitosan, vanadyl sulfate or methyl jasmonate on growth and ginsenoside production of three stable hairy root lines of Panax ginseng C.A. Meyer showing different morphological phenotypes C-M, HR-M and T-M. The response depended upon line phenotype, specificity of the elicitor and the stage of growth at which the lines were treated. The highest ginsenoside yield was found when methyl jasmonate was added during the progressive deceleration growth phase (on day 25 of culture). In this case, the ginsenoside content reached at the end of the culture (day 28) by root lines C-M, HR-M and T-M was, respectively, 2, 1.8 and 4 times higher than the highest content achieved, also at the end of the culture, by the corresponding untreated root lines. Under the same conditions, the ginsenoside content in the presence of vanadyl sulfate also increased considerably, while with chitosan it clearly decreased. The ginsenoside pattern in response to the presence of the elicitors is also considered.     

Defense response mechanisms of ginseng callus cultures induced by Yersinia pseudotuberculosis, a human pathogen

The effect of Yersinia pseudotuberculosis, the bacterial pathogen affecting humans and animals, on growth of ginseng (Panax ginseng C.A. Mey) cell cultures was studied. The bacteria strongly induced the expression of phenylalanine ammonia-lyase and β-1,3-glucanase, the proteins encoded by the defense-related genes of ginseng and inhibited the normal ginseng callus growth but did not affect the resistant cell cultures. The thermostable and thermolabile protein toxins of these bacteria are lethal to mice when induced parentherally, and they also induced the expression of the defense-related genes in ginseng callus cultures. At the same time, the ginseng cells completely suppressed the bacterial cell growth. These data suggest that the ginseng cells recognized the yersinia and developed the immune response to this pathogen. The interaction between the ginseng cells and Y. pseudotuberculosis is similar to the hypersensitive response of plants to plant pathogens.     

Biotransformation of p-, m-, and o-hydroxybenzoic acids by Panax ginseng hairy root cultures

The regioselective glycosylation of three isomers of hydroxybenzoic acids was observed in Panax ginseng hairy root cultures. p-Hydroxybenzoic acid (1) and m-hydroxybenzoic acid (2) were converted into their corresponding glycosides (1a and 2a) and glycosyl esters (1b and 2b) while no metabolite of o-hydroxybenzoic acid (3) was detected. A new compound, m-hydroxybenzoic acid β-d-xylopyranosyl (1 → 6)-β-d-glycopyranosyl ester (2c) was identified as a biotransformation product of 2. Further time-course studies of the biotransformation reactions showed that the glycosides were major products in the latter stage. The addition of carbohydrates or antioxidants increased glycosyl esters formation.