The relationship between shifts in the rhizosphere microbial community and root rot disease in a continuous cropping American ginseng system

The root rot disease causes a great economic loss, and the disease severity usually increases as ginseng ages. However, it is still unclear whether the disease severity is related to changes in microorganisms during the entire growing stage of American ginseng. The present study examined the microbial community in the rhizosphere and the chemical properties of the soil in 1-4-year-old ginseng plants grown in different seasons at two different sites. Additionally, the study investigated ginseng plants' root rot disease index (DI). The results showed that the DI of ginseng increased 2.2 times in one sampling site and 4.7 times in another during the 4 years. With respect to the microbial community, the bacterial diversity increased with the seasons in the first, third, and fourth years but remained steady in the second year. The seasonal changing of relative abundances of bacteria and fungi showed the same trend in the first, third, and fourth years but not in the second year. Linear models revealed that the relative abundances of Blastococcus, Symbiobacterium, Goffeauzyma, Entoloma, Staphylotrichum, Gymnomyces, Hirsutella, Penicillium and Suillus spp. were negatively correlated with DI, while the relative abundance of Pandoraea, Rhizomicrobium, Hebeloma, Elaphomyces, Pseudeurotium, Fusarium, Geomyces, Polyscytalum, Remersonia, Rhizopus, Acremonium, Paraphaeosphaeria, Mortierella, and Metarhizium spp. were positively correlated with DI (P < 0.05). The Mantel test showed that soil chemical properties, including available nitrogen, phosphorus, potassium, calcium, magnesium, organic matter, and pH, were significantly correlated to microbial composition. The contents of available potassium and nitrogen were positively correlated with DI, while pH and organic matter were negatively correlated with DI. In summary, we can deduce that the second year is the key period for the shift of the American ginseng rhizosphere microbial community. Disease aggravation after the third year is related to the deterioration of the rhizosphere microecosystem.

[Effect of light intensity on growth, accumulation of ginsenosides, and expression of related enzyme genes of Panax quinquefolius]

Appropriate light intensity is favorable for the photosynthesis, biomass accumulation, key enzyme activity, and secondary metabolite synthesis of medicinal plants. This study aims to explore the influence of light intensity on growth and quality of Panax quinquefolius. To be specific, sand culture experiment was carried out in a greenhouse under the light intensity of 40, 80, 120, and 160 μmol·m~(-2)·s~(-1), respectively. The growth indexes, photosynthetic characteristics, content of 6 ginsenosides of the 3-year-old P. quinquefolius were determined, and the expression of ginsenoside synthesis-related enzyme genes in leaves, main roots, and fibrous roots was determined. The results showed that the P. quinquefolius growing at 80 μmol·m~(-2)·s~(-1) light intensity had the most biomass and the highest net photosynthetic rate. The total biomass of P. quinquefolius treated with 120 μmol·m~(-2)·s~(-1) light intensity was slightly lower than that with 80 μmol·m~(-2)·s~(-1). The root-to-shoot ratio in the treatment with 120 μmol·m~(-2)·s~(-1) light intensity was up to 6.86, higher than those in other treatments(P&lt;0.05),and the ginsenoside content in both aboveground and underground parts of P. quinquefolius in this treatment was the highest, which was possibly associated with the high expression of farnesylpyrophosphate synthase(FPS), squalene synthase(SQS), squalene epoxidase(SQE), oxidosqualene cyclase(OSC), dammarenediol-Ⅱ synthase(DS), and P450 genes in leaves and SQE and DS genes in main roots. In addition, light intensities of 120 and 160 μmol·m~(-2)·s~(-1) could promote PPD-type ginsenoside synthesis in leaves by triggering up-regulation of the expression of upstream ginsenoside synthesis genes. The decrease in underground biomass accumulation of the P. quinquefolius grown under weak light(40 μmol·m~(-2)·s~(-1)) and strong light(160 μmol·m~(-2)·s~(-1)) was possibly attributed to the low net photosynthetic rate, stomatal conductance, and transpiration rate in leaves. In the meantime, the low expression of SQS, SQE, OSC, and DS genes in the main roots might led to the decrease in ginsenoside content. However, there was no significant correlation between the ginsenoside content and the expression of synthesis-related genes in the fibrous roots of P. quinquefolius. Therefore, the light intensity of 80 and 120 μmol·m~(-2)·s~(-1) is beneficial to improving yield and quality of P. quinquefolius. The above findings contributed to a theoretical basis for reasonable shading in P. quinquefolius cultivation, which is of great significance for improving the yield and quality of P. quinquefolius through light regulation.

[The effects of robotic-assisted versus laparoscopic-assisted radical right hemicolectomy on short-term outcome and long-term prognosis based on propensity score matching]

Objective: To compare the short-term and long-term outcomes between robotic-assisted and laparoscopic-assisted radical right hemicolectomy in patients with adenocarcinoma of the right colon. Methods: Retrospective review of a prospectively collected database identified 288 right colon cancer patients who underwent either robotic-assisted (n=57) or laparoscopic-assisted right hemicolectomy (n=231) between October 2014 and October 2020 at Department of Gastrointestinal Surgery, the Affiliated Hospital of Qingdao University. There were 161 males and 127 females, aging (60.3±12.8) years (range: 17 to 86 years). After propensity score matching as 1∶4 between robotic-assisted and laparoscopic-assisted right hemicolectomy, there were 56 cases in robotic group and 176 cases in laparoscipic group. Perioperative outcomes and overall survival were compared between the two groups using t test, Wilcoxon rank sum test, χ² test, Fisher exact test, Kaplan-Meier method and Log-rank test, respectively. Results: The total operative time was similar between the robotic and laparoscopic group ((206.9±60.7) minutes vs. (219.9±56.3) minutes, t=-1.477, P=0.141). Intraoperative bleeding was less in the robotic group (50 (20) ml vs. 50 (50) ml, Z=-4.591, P<0.01), while the number of lymph nodes retrieved was significantly higher (36.0±10.0 vs. 29.0±10.1, t=4.491, P<0.01). Patients in robotic group experienced significantly shorter hospital stay, shorter time to first flatus, and defecation (t: -2.888, -2.946, -2.328, all P<0.05). Moreover, the overall peri-operative complication rate was similar between robotic and laparoscopic group (17.9% vs. 22.7%, χ²=0.596,P=0.465). The 3-year overall survival were 92.9% and 87.9% respectively and the 3-year disease-free survival rates were 83.1% and 82.6% with no statistical significance between the robotic and laparoscopic group (P>0.05). Conclusions: Compared to laparoscopic-assisted right hemicolectomy, robot-assisted right hemicolectomy could improve some short-term clinical outcomes. The two procedures are both achieving comparable survival.

Application of vermicompost and biochar suppresses Fusarium root rot of replanted American ginseng

Soil sterilization integrated with agronomic measures is an effective method to reduce soilborne replant diseases. However, the effect of vermicompost or biochar application after soil sterilization on soilborne diseases is poorly understood. A pot experiment was conducted in American ginseng to investigate the effects of vermicompost (VF), biochar (BF), and a combination of vermicompost and biochar (VBF) applied after soil sterilization on the incidence of Fusarium root rot using natural recovery (F) as control. After one growing season, the disease index of root rot, the phenolic acids, and the microbial communities of American ginseng rhizosphere soil were analyzed. The disease index of VF, BF, and VBF decreased by 33.32%, 19.03%, and 80.96%, respectively, compared with F. The highest bacterial richness and diversity were observed in the rhizosphere soil of VBF. Besides, VF and VBF significantly increased the relative abundance of beneficial bacteria (Pseudomonas, Lysobacter, and Chryseolinea) in the rhizosphere soil. Higher concentrations of vanillin, one of the phenolic acids in the roots exudates, were recorded in the rhizosphere soils of BF and VBF. The vanillin concentration showed a significant negative correlation with the disease index. To conclude, vermicompost improved the beneficial bacteria of the rhizosphere soil, while biochar regulated the allelopathic effect of the phenolic acids. The study proposes a combined application of biochar and vermicompost to the rhizosphere soil to control Fusarium root rot of replanted American ginseng effectively. KEY POINTS: Vermicompost improves the relative abundance of rhizosphere beneficial bacteria. Biochar inhibits the degradation of phenolic acids by adsorption. The combination of vermicompost and biochar enhances the disease control effect.

[Effects of nutrients deficiency on growth and saponin accumulation of American ginseng]

Mineral nutrient elements are the key factors to maintain the growth and quality of American ginseng. In order to understand the comprehensive effect of different nutrient elements deficiency on American ginseng, 2-year-old American ginsengs were cultivated by Hoagland solution(CK) or 10 different nutrients deficiency solution in sand culture. During the cultivation, the deficient symptom was observed. The plant height, leaf area, biomass, photosynthetic index, root activity, ginsenoside content were measured. The results showed that N, K or Fe deficiency could lead to leaves of American ginseng yellowing. Deficiency N, K, Ca, Mg and B were the main factors that decrease plant height and leaf area. The biomass of plant decreased significantly in all the nutrient deficient treatments(P<0.05)compared with control group, and N, K, Ca or Fe deficiency groups descended over 50%. In the absence of N, K and Fe elements, the P_n, G_s, C_i, T_r and chlorophyll of leaves were decreased mostly. The first three factors decreasing root activity were N, K and Ca deficiency. The effects of nutrient deficiency on saponins of American ginseng were different.Generally, N, P, B, Zn and Cu deficiency resulted the synthesis of saponins decreased significantly(P<0.05). This study contributed to clarify the demand characteristics of American ginseng for different nutrient elements,which is of great significance for the diagnose of nutrient deficiency, the rational fertilizer and the improvement of yield and quality of American ginseng.

[Investigation of aflatoxins,mycobiota,and toxigenic fungi during post-harvest handling of Ziziphi Spinosae Semen]

Ziziphi Spinosae Semen is one of the Chinese herbal medicine being susceptible to aflatoxins contamination. To investigate the sources of aflatoxins contamination and toxigenic fungi species on Ziziphi Spinosae Semen,32 samples were collected from multiple steps during the post-harvest processing in this study. Aflatoxins in these samples were determined by immunoaffinity column and HPLC coupled with post-column photochemical derivatization. The dilution-plate method was applied to the fungi isolation. The isolated fungi strains were identified by morphological characterization and molecular approaches. The results showed that aflatoxins were detected in 28 samples from every step during the processing of Ziziphi Spinosae Semen. Three samples were detected with aflatoxin B_1 and 2 samples with both aflatoxin B_1 and total aflatoxin exceeding the limit of Chinese Pharmacopoeia. Especially the samples from the washing step,with the highest detected amounts of AFB_1 and AFs were reached 94. 79,121. 43 μg·kg~(-1),respectively. All 32 samples were contaminated by fungi. The fungal counts on the newly harvested samples were 2. 20 × 10~2 CFU·g~(-1). Moreover,it increased as tphreocessing progresses,and achieved 1. 16×10~6 CFU·g~(-1) after washing. A total of 321 isolates were identified to 17 genera. Aspergillus flavus was the main source of aflatoxins during the processing and storage of Ziziphi Spinosae Semen. One isolate of A. flavus was confirmed producing AFB_1 and AFB_2. The fungal count was significantly increased by composting,and Aspergillus was the predominant genus after shell breaking. The contamination level of aflatoxins was increased by composting and washing.

Effects of maize rotation on the physicochemical properties and microbial communities of American ginseng cultivated soil

The production of American ginseng (Panax quinquefolius L.) is severely limited by the replant disorders in China. Crop rotation with maize might reduce the replant problems, but little information is available on the effect of maize rotation on soil cultivated with ginseng. In this study, we analyzed nutrients, phenolic acids, and microbial communities in soils from the fields with continuous maize, mono-culture ginseng, and 1-, 3-, and 5-year maize rotation after ginseng. Pot experiments were also conducted to evaluate the performance of replanting ginseng in these soils. The results showed that Mn, Cu, and 5 phenolic acids in ginseng-cultivated soil were significantly decreased by maize rotation. A 5-year maize rotation significantly increased the relative abundance of beneficial soil bacteria, such as Arthrobacter, rather than decreasing the abundances of potential pathogenic genera. Clustering analysis revealed that the physicochemical properties and microbial communities of 3- and 5-year maize rotation soil were more similar to CM than to G soil. The biomass of replanted ginseng root was improved, and root disease was reduced over 3 years of maize rotation. Overall, the results showed that at least a 3-year maize rotation is needed to overcome the replant failure of American ginseng.

Relation between therapy options for Graves' disease and the course of Graves' ophthalmopathy: a systematic review and meta-analysis

BACKGROUND

The relation between therapy options for Graves' disease (GD) and the course of Graves' ophthalmopathy (GO) are still controversial. Our aim was to compare the occurrence of development or worsening of GO in patients who were treated with antithyroid drugs (ATDs) or radioactive iodine (RAI) or thyroidectomy (TX).

METHODS

We conducted a comprehensive search of the Embase and PubMed database. Odds ratio (OR) was used as a measure of the effect of therapy options for GD on the risk of development or worsening of GO. The analysis was further stratified by factors that could affect the treatment effects.

RESULTS

Nine trials involving 1773 patients were included. RAI therapy showed a significant effect on the risk of development or worsening GO compared with ATD (OR 2.25; 95 % CI 1.61-3.14; P < 0.00001). Glucocorticoid prophylaxis was effective in preventing GO development or worsening (0.40; 0.23-0.68; P = 0.002); especially for patients with preexisting GO (0.41; 0.23-0.73; P = 0.002). At 3 months, showed GO to be improved in 17 TX and 21 total thyroid ablation (TTA) patients, with no significant difference between the two groups; between 6 and 12 months, TTA did show significant beneficial effect on the improvement of GO (6.02; 2.80-12.96; P < 0.00001); GO was found to be inactive in a significantly higher percentage of patients in the TTA (2.17; 1.04-4.52; P = 0.04).

CONCLUSION

Radioiodine therapy is a significant risk factor for development or worsening of GO in GD. But GO progression can be prevented by prophylactic glucocorticoids in patients with preexisting GO. Compared with TX alone, TTA induces an earlier and steadier GO improvement in patients with mild to moderate-severe and active GO. Whether this is sufficient to offer TTA to patients needs further investigation.

Effect of weaning age on cortisol release in piglets

The effect of weaning age on the adrenal cortex, which plays a vital role in the stress response, is currently unknown. Therefore, plasma adrenocorticotropic hormone (ACTH) and cortisol levels, weights and relative weights of adrenal glands, and steroidogenesis-related protein and enzyme expression levels in piglets weaned on different days were determined. Piglets weaned at 35 days had significantly lower ACTH levels than those weaned at 14 or 21 days, and cortisol levels of piglets weaned at 21, 28, and 35 days were significantly lower than those of piglets weaned on day 14. Adrenal gland weights of piglets weaned at 28 and 35 days and relative adrenal gland weights of piglets weaned at 35 days were significantly lower than those of piglets weaned at 14 days. However, no significant difference was detected in the expression of melanocortin-type 2 receptor mRNA, which is associated with weaning age. Steroidogenic acute-regulatory (StAR) mRNA and cholesterol side-chain cleavage cytochrome P450 mRNA expression levels in piglets weaned at 28 and 35 days were significantly lower than in those weaned at 14 or 21 days, and P450 11β mRNA expression levels in piglets weaned at 28 and 35 days were significantly lower than in those weaned at 14 days. Therefore, early-weaned piglets exhibited increased adrenal gland weights and StAR and steroidogenic enzyme expression, all of which contributed to high cortisol levels. The high plasma ACTH and cortisol levels in early-weaned piglets indicate that these animals would be greatly affected by stress.

First Report of Ilyonectria robusta Causing Rusty Root of Asian Ginseng in China

Asian ginseng (Panax ginseng) is an economically important perennial herb, mainly cultivated in Jilin Province, China. In September 2013, Asian ginseng plants in Jilin showed rusty root symptoms. Typical symptoms included rusty superficial lesions of irregular shapes and margins. Ten symptomatic roots were collected from each of five fields for investigation. To isolate the pathogen, root epidermal tissues with typical lesions were excised, surface-sterilized, and placed on potato dextrose agar (PDA) amended with 50 μg/ml tetracycline. After incubation at 20 ± 1°C in the dark for a week, 18 single-spore isolates out of 50 samples were obtained and identified as Ilyonectria robusta (A.A. Hildebr.) A. Cabral & Crous based on morphological characters and DNA sequence analysis (1). After incubating 7 days on PDA in the dark at 20°C, colonies were cottony to felty in texture and orange white to brownish grey in color with average diameters of 60 ± 3 mm. Isolates were cultured on synthetic nutrient-poor agar for conidial measurements. Macroconidia formed on simple conidiophores predominately, with mostly one and occasionally up to three septa, and were cylindrical with both ends broadly rounded. Macroconidia varied in size depending on the number of cells as follows: one-septate, 7.0 ± 0.6 × 27.7 ± 2.7 μm; two-septate, 7.3 ± 0.7 × 33.3 ± 2.1 μm; three-septate, 7.4 ± 0.6 × 33.4 ± 2.2 μm. Microconidia that formed on complex conidiophores were ellipsoid to ovoid and ranged in size from aseptate 3.7 ± 0.5 × 8.7 ± 1.1 μm to one-septate 5.0 ± 0.6 × 13.1 ± 1.6 μm. Brown chlamydospores were abundantly produced on PDA, globose to subglobose in shape, and in size of 10.9 ± 1.3 × 11.8 ± 1.5 μm (n ≥ 30 observations per structure for each measurement). The isolates were further classified by amplifying and sequencing the ITS1-5.8S rRNA-ITS2 region and histone H3 gene with primer pairs ITS5 and ITS4 (4), and H3-1a and H3-1b (3), respectively. Sequences of the two loci (GenBank Accession Nos. KM015300 and KM015299) showed 100% identity among the three examined isolates and the published I. robusta isolates (JF735268 and JF735517). To confirm the pathogenicity, bare roots of 3-year-old Asian ginseng were inoculated with mycelial plugs of three isolates of I. robusta selected randomly. Four roots were inoculated as replicates for each isolate with pathogen-free agar plugs as a control. One week post-inoculation in the dark at 20 ± 1°C, all the inoculated ginseng roots showed light-brown to dark-brown lesions. I. robusta was recovered from symptomatic roots and confirmed by analyzing the DNA sequence of the histone H3 gene. The inoculation experiment was repeated, and both trials showed the same results. The ginseng tissue under the control agar plugs remained symptomless, and no fungi were isolated. To our knowledge, this is the first report of I. robusta causing rusty root of P. ginseng in China (1,2,5). References: (1) A. Cabral et al. Mycol. Prog. 11:655, 2012. (2) I. Erper et al. Eur. J. Plant Pathol. 136:291, 2013. (3) N. L. Glass et al. Appl. Environ. Microbiol. 61:1323, 1995. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (5) X. Lu et al. Plant Dis. 98:1580, 2014.

First Report of Rhexocercosporidium panacis Causing Rusty Root of Panax ginseng in Northeastern China

In northeastern China, Asian ginseng (Panax ginseng) roots exhibited reddish brown lesions of various sizes, irregular shapes, and diffuse margins, typical of rusty root disease. The lesions remain superficial, smooth, and limited to the epidermal and peridermal tissues. In September 2013, 10 symptomatic roots were collected from each of three fields in Jilin and Heilongjiang provinces. One piece of symptomatic skin tissue from each root was excised, surface-disinfested in 1% NaClO for 3 min, rinsed three times with sterile water, and then placed on tetracycline-amended (50 μg/ml) potato dextrose agar. After incubation at 22 ± 1°C in the dark for a week, small olivaceous black colonies developed from the symptomatic tissue from five of the 30 samples. No spores were observed. A single hyphal tip of each colony was transferred to a fresh V8 agar plate to purify the culture. Two-week-old colonies on V8 agar were olivaceous gray, and 42 to 46 mm in diameter with an outer white margin (3 to 5 mm wide). Conidia produced in V8 broth after 3 weeks with a 12-h photoperiod were straight and hyaline, cylindrical or subcylindrical with no or one septum. Mature conidia were 12.8 to 21.8 × 2.2 to 4.5 μm (mean 18.2 × 3.0 μm, n = 100 conidia for each of three isolates). Three isolates selected randomly were further identified by analyzing the partial sequences of the ITS region of rDNA with primers ITS4 and ITS5 (5), and partial sequences of β-tubulin with the primers tub2F and tub2R (1). Sequences of the three isolates (GenBank Accession Nos. KJ149287, KJ149288, and KJ149290 to 93) showed 99% to 100% homology with previously identified and deposited Rhexocercosporidium panacis isolates (DQ2499992 and DQ457119) for both loci (3). Therefore, the three isolates were identified as R. panacis and deposited in China General Microbiological Culture Collection Center (CGMCC3.17259 to 61). Pathogenicity of R. panacis in Asian ginseng was investigated using these three isolates as described previously with slight modifications (4). Bare roots of 3-year-old Asian ginseng were surface-disinfested as described above, and inoculated with mycelial plugs (4 mm diameter) cut from the margin of actively growing colonies of the isolates on V8 agar. Three mycelial plugs were placed on each root at 3-cm intervals and four roots (replicates) were inoculated for each isolate. Four additional roots were inoculated with non-colonized agar plugs as control. The treated roots were placed on moist filter paper in an enamel tray. The plates were sealed with plastic wrap to prevent desiccation and incubated in the dark at 18 ± 1°C. Four weeks post inoculation, all the inoculated ginseng roots showed red-brown lesions, which turned to dark red or black over time. R. panacis was recovered from symptomatic roots for all isolates and confirmed by ITS sequence analysis. The mock-inoculated control roots remained symptomless and no R. panacis was isolated. The inoculation experiment was repeated and showed the same results. R. panacis was reported in 2006 to infect roots of Panax quinquefolius (2,3,4). To our knowledge, this is the first report of R. panacis causing rusty root of P. ginseng. References: (1) P. R. Hirsch et al. Mycol. Res. 104:435, 2000. (2) Z. K. Punja et al. Can. J. Plant Pathol. 35:503, 2013. (3) R. D. Reeleder. Mycologia. 99:91, 2007. (4) R. D. Reeleder et al. Phytopathology 96:1243, 2006. (5) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

Lactoferrin mRNA expression in mouse mammary glands during pregnancy and lactation

Lactoferrin (Lf) is an iron-binding glycoprotein that is produced by mucosal epithelial cells in mammals. Lf has non-immune natural defense functions and biological functions in addition to and distinct from its role in regulating inflammatory responses. Lf also improved some physiological and immunological parameters. Lf is a biomarker for monitoring medical treatment in inflammatory bowel diseases. Current LF research focuses on iron absorption, antimicrobial activity, and the modulation of iron metabolism during inflammation. No systematic research about Lf expression levels in mouse mammary glands during pregnancy and lactation exists. We investigated Lf mRNA expression levels in mouse mammary glands by collecting samples on days 1, 6, 12, and 18 of pregnancy and lactation (six mice per group). The expression levels of Lf mRNA were measured by semi-quantitative reverse transcription polymerase chain reaction using GAPDH as an internal control. Lf mRNA was not expressed in mammary glands on days 1, 6, and 12 of pregnancy, but it was expressed on day 18 (IOD: integrated optical density; Lf(IOD)/GAPDH(IOD) = 0.46). Lf expression levels were higher during lactation stages than during pregnancy stages, and it stabilized at 0.71-0.73 (Lf(IOD)/GAPDH(IOD)) from day 1 to 12 of lactation; however, the difference was not significant (P > 0.05). At day 18 of lactation, Lf expression began to decline (Lf(IOD)/GAPDH(IOD) = 0.61), but the difference was not significant (P > 0.05). Based on these results, the variation in Lf expression levels during developmental stages may be related to its regulatory role in mouse mammary gland immunity.

Prognostic significance of PUMA in pancreatic ductal adenocarcinoma

OBJECTIVES

To investigate retrospectively whether alterations of p53 upregulated mediator of apoptosis (PUMA) protein levels and somatic mutations of the PUMA gene are characteristic of pancreatic ductal adenocarcinoma (PDAC).

METHODS

Immunohistochemical analyses of PUMA were performed in pancreatic tumour tissue samples, and paired normal pancreatic tissue samples, from patients with PDAC. Apoptosis was detected using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling assay.

RESULTS

A total of 70 patients with PDAC had samples available; 49 cases (70.0%) had high PUMA protein levels. PUMA was not detected in paired normal tissue samples. Significantly higher levels of PUMA protein were detected in low-grade tumours (tumour -node-metastasis stages I and II), compared with higher grade (stage III) tumours. Of the PDAC cases, the mean apoptosis index value for PUMA-positive specimens was significantly higher than that for PUMA-negative specimens. Overall survival was significantly associated with PUMA immunoreactivity.

CONCLUSIONS

High levels of PUMA in PDAC tumour cells suggest that PUMA expression may play a role in pancreatic tumourigenesis.

[Effect of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium]

OBJECTIVE

To analyze the effects of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium, and the correlation between rhizosphere fungal community and growth of P. quinquefolium.

METHOD

Field plot trail of continuous cultivated P. quinquefolium was conducted, meanwhile continuous cropping soil was treated by organic carbon fertilizer plus methylene dithiocyanate and Kingbo respectively. The rate of seedling survival, root disease index and root weight were investigated. Dilution plating was used to analyze the rhizosphere fungal community, multiple comparisons including H, M(a) and J were performed between rhizosphere fungal community and growth of P. quinquefolium.

RESULT

As to P. quinquefolium planted in continuous soil, the rate of seedling survival, root weight decreased, root disease index increased remarkably (P<0.05). Meanwhile the fungal counts decreased 50% -63% , the diversity index (H') decreased 39%-43%, while the ratio of Penicillium and Aspergillus increased. There was a significant negative correlation between rhizosphere fungal diversity and P. quinquefolium root disease index (r = -0.970, P=0.006). Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the rate of seedling survival and root weight, and could partly increase the rhizosphere fungal diversity.

CONCLUSION

In continuous cropping soil of P. quinquefolium, the rhizosphere fungal counts and diversity index decreased, meanwhile the fungal community composition changed. Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the growth of continuous cultivated P. quinquefolium.

[Variation of ginsenosides in infected roots of American ginseng (Panax quinquefolium)]

To study the infected root of Panax quinquefolium on the contents of ginsenosides.

METHOD

The contents of three major ginsenosides Rg1, Re and Rb1 were determined by HPLC compared quantitatively between the different degree infected roots and normal root in the phloem and xylem.

RESULT

Rg1 in phloem and xylem of varying degrees infected root showed no significant difference, but Rb1 decreased 26.3% and 28.3% respectively in medium and serious infected roots comparing to normal root. Re in phloem of seriously infected roots decreased in xylem significantly.

CONCLUSION

The results indicate that the variation of ginsenosides in different degrees infected roots exists and the proportion of Rg1, Re and Rb1 in the total ginsenosides changes.