Ginseng Production Research Articles

Untargeted Metabolomics and Soil Community Metagenomics Analyses Combined with Machine Learning Evaluation Uncover Geographic Differences in Ginseng from Different Locations.

Panax ginseng C.A. Meyer, known as the "King of Herbs," has been used as a nutritional supplement for both food and medicine with the functions of relieving fatigue and improving immunity for thousands of years in China. In agricultural planting, soil environments of different geographical origins lead to obvious differences in the quality of ginseng, but the potential mechanism of the differences remains unclear. In this study, 20 key differential metabolites, including ginsenoside Rb1, glucose 6-phosphate, etc., were found in ginseng from 10 locations in China using an ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS)-untargeted metabolomics approach. The soil properties were analyzed and combined with metagenomics technology to explore the possible relationships among microbial elements in planting soil. Through Spearman correlation analysis, it was found that the top 10 microbial colonies with the highest abundance in the soil were significantly correlated with key metabolites. In addition, the relationship model established by the random forest algorithm and the quantitative relationship between soil microbial abundance and ginseng metabolites were successfully predicted. The XGboost model was used to determine 20(R)-ginseng Rg2 and 2'(R)-ginseng Rg3 as feature labeled metabolites, and the optimal ginseng production area was discovered. These results prove that the accumulation of metabolites in ginseng was influenced by microorganisms in the planting soil, which led to geographical differences in ginseng quality.

Deciphering the key soil microbial taxa that contribute to saponin accumulation in a geo-authentic Sanqi ginseng production area: Evidence from four different varieties

Sanqi ginseng (Panax notoginseng) is a typical geo-authentic medicinal herb and the accumulation of saponins heavily relies on its growing environment. However, the effects of soil factors on saponin accumulation are still not well characterized. In this study, four different varieties (improved varieties: KZ, HD and PK; common variety: PT) and two typical soils (geo-authentic soil: QB; non-geo-authentic soil: SL) were selected for pot experiments, and the root biomass and saponin content, as well as the soil microbiome were investigated after one-year of cultivation. Results showed that soil, rather than variety, was the determinant of the root development and saponin accumulation of Sanqi ginseng. Sanqi ginseng cultivated in the QB soil had better root morphology (with long and dense fibrous roots) and higher saponin accumulation. Compared to the physicochemical properties, the soil microbiome exhibited a higher explanatory power (24.68 %) for the biomass and saponin of Sanqi ginseng, and its α-diversity and β-diversity were strongly related to biomass, saponin content and saponin accumulation. Random forest regression analysis further revealed that those having high and positive contributions to biomass and saponin accumulation, such as bacterial genera Arthrobacter, Gaiella, Granulicella, Bradyrhizobium, Rhizomicrobium, Rhizobium and Streptomyces, and fungal genera Fusarium, Plenodomus, Setophoma and Trichoderma, were significantly enriched in QB soil. This study revealed that soil is one of the key factors for producing geo-authentic Sanqi ginseng and highlighted the importance of key soil microbial taxa in the saponin accumulation of Sanqi ginseng, thus providing a theoretical basis for quality improvement through microbiome regulation.

Analysis of ginseng rusty root symptoms transcriptome and its pathogenesis directed by reactive oxygen species theory.

Ginseng rusty root symptoms (GRS) is a primary disease of ginseng, which seriously decreases the yield and quality of ginseng and causes enormous losses to ginseng production. GRS prevention and control is still challenging due to its unclear etiology. In this study, the phloem tissue of healthy Panax ginseng (AG), the nonred tissue of the phloem epidermis around the lesion (BG), and the red lesion site tissue of GRS (CG) were extracted for mRNA transcriptomic analysis; 35,958 differentially expressed genes (DEGs) were identified and were associated with multiple stress resistance pathways, reactive oxygen species (ROS), and iron ion binding. Further study showed that the contents of O2 •-, H2O2, and malondialdehyde (MDA) were significantly increased in BG and CG tissues. Under anaerobic conditions caused by excessive soil moisture, the overproduction of ROS destroys cell membranes, simultaneously converting Fe2+ to Fe3+ and depositing it in the cell wall, which results in GRS, as evidenced by the success of the GRS induction test.

Assessment of drying characteristics for whole and sliced red ginseng using short‐wave infrared spectroscopy and mathematical model

AbstractMonitoring the moisture content is crucial for red ginseng quality control. In this study, we established a moisture content prediction model using partial least squares regression (PLSR) based on short‐wave infrared (SWIR) data of different ginseng types (whole and sliced) at various drying temperatures and times. The model parameters, including the R2 values, ratio of prediction deviation, and range error ratio, showed that the developed model was robust. Sliced ginseng showed a constant rate period, followed by a falling rate period, whereas whole ginseng showed only a falling rate period. The falling‐rate period coincided with the formation of a dry zone on the sample surface in the moisture distribution map, indicating that monitoring the moisture distribution map can predict the onset of the falling‐rate period. These results suggest that the SWIR technique is a promising nondestructive method for evaluating the drying process of red ginseng.Practical applicationsMonitoring the moisture content of red ginseng is essential to prevent microbial spoilage during transportation. Traditional monitoring of water content is destructive and time‐consuming. Therefore, using hyperspectral imaging, we aimed to develop an efficient moisture prediction model for the drying process of red ginseng. We believe that our study makes a significant contribution to non‐destructive and rapid quality evaluation in red ginseng production.

A Portable Nucleic Acid Sensor Based on PCR for Simple, Rapid, and Sensitive Testing of Botrytis cinerea in Ginseng.

Botrytis cinerea is a ubiquitous pathogen that can infect at least 200 dicotyledonous plant species including many agriculturally and economically important crops. In Ginseng, the fungus may cause ginseng gray mold disease, causing great economic losses in the ginseng industry. Therefore, the early detection of B. cinerea in the process of ginseng production is necessary for the disease prevention and control of the pathogen's spread. In this study, a polymerase chain reaction-nucleic acid sensor (PCR-NAS) rapid detection technique was established, and it can be used for field detection of B. cinerea through antipollution design and portable integration. The present study showed that the sensitivity of PCR-NAS technology is 10 times higher than that of traditional PCR-electrophoresis, and there is no need for expensive detection equipment or professional technicians. The detection results of nucleic acid sensors can be read by the naked eye in under 3 min. Meanwhile, the technique has high specificity for the detection of B. cinerea. The testing of 50 field samples showed that the detection results of PCR-NAS were consistent with those of the real-time quantitative PCR (qPCR) method. The PCR-NAS technique established in this study can be used as a novel nucleic acid field detection technique, and it has a potential application in the field detection of B. cinerea to achieve early warning of the pathogen infection.

Prediction of global potential growth areas for Panax ginseng based on GMPGIS system and MaxEnt model

The suitable habitat for the endangered and valuable medicinal herb Panax ginseng is gradually decreasing. It is crucial to investigate its suitable growing areas in China for global protection and sustainable utilization of P. ginseng. In this study, 371 distribution points of P. ginseng were collected, and 21 environmental factors were used as ecological indicators. The geographic information system for global medicinal plants(GMPGIS) system, MaxEnt model, and Thiessen polygon method were used to analyze the potential suitable areas for P. ginseng globally. The results showed that the key environmental variables affecting P. ginseng were precipitation in the hottest quarter(Bio18) and the coefficient of temperature seasonality(Bio4). The suitable habitats for P. ginseng were mostly located in the "One Belt, One Road" countries such as China, Japan, South Korea, North Korea, and Russia. The highly suitable habitats were mainly distributed along mountain ranges in southeastern Shandong, southern Shanxi and Shaanxi, northern Jiangsu, and northwestern Henan of China. Data analysis indicated that the current P. ginseng planting sites were all in high suitability zones, and the Thiessen polygon results showed that the geographic locations of P. ginseng production companies were unbalanced and urgently needed optimization. This study provides data support for P. ginseng planting site selection, scientific introduction, production layout, and long-term development planning.

First report of root rot caused by Fusarium commune on American ginseng (Panax quinquefolium L.) in China.

American ginseng (Panax quinquefolium L.) is one of the most valuable herb crops because of its unique pharmacological effects. In 2019, American ginseng plants withered and root rot with incidences of 20-45% were observed in about 70000m2 of ginseng production field located in mountainous valley of Benxi city (41º23'32" N, 124º04'27" E), Liaoning Province in China. Disease symptoms included chlorotic leaves with dark brown discoloration extending gradually from the basal to the apical part of the leaves. Water-soaked, irregular lesions appeared on the surface of roots and rotten at later stage. Twenty-five symptomatic roots were surface-sterilized by immersion in 2% sodium hypochlorite (NaOCl) for 3 min, followed by rinsing three times in sterilized water. The sections healthy tissues bordered rotten tissues, i.e. the leading edge, were cut into 4-5 mm pieces with a sterile scalpel and 4 pieces were placed on each PDA plate. After 5 days incubation at 26°C, total of 68 single spores were obtained from the colonies with an inoculation needle under stereomicroscope. Colonies from single conidia were white to greyish white, densely floccose to fluffy, and the reverse grayish yellow with dull violet pigmentation. Single-celled and ovoid microconidia in false heads were borne on aerial monophialidic or polyphialidic conidiophores on Carnation Leaf Agar (CLA) media, and measured 5.0 -14.5 × 3.0 -4.8 μm (n=25). Macroconidia were two to four septa, slightly curved, apical and basal cells were also curved, and they measured 22.5 - 45.5 × 4.5 - 6.3 μm (n=25). Chlamydospores were singly or in pairs, circular or subcircular, smooth, and measuring 5 - 10.5 μm (n=25) in diameter. Morphologically, the isolates were identified as Fusarium commune (Skovgaard et al. 2003; Leslie and Summerell 2006 ). To confirm the identity, the rDNA partial translation elongation factor1 alpha (TEF-a) gene and the internal transcribed spacer (ITS) region of ten isolates were amplified and sequenced (O'Donnell et al. 2015; White et al. 1990). Identical sequences were obtained, and one representative sequence of isolate BGL68 was submitted to GenBank. BLASTn analysis of both the TEF-α (MW589548) and the ITS (MW584396) sequences, revealed 100% and 99.46 % sequence identity to F. commune MZ416741 and KU341322, respectively. The pathogenicity test was conducted under greenhouse conditions. The surface of healthy 2-year-old American ginseng roots was washed and disinfested in 2% NaOCl for 3 min before rinsing in sterilized water. Twenty roots were wounded with a toothpick, resulting in tiny perforations (1.0 × 1.0×3.0 mm), 3 perforations were wounded on each root. Inoculums was prepared from the culture of isolate BGL68 incubate in potato dextrose broth (PD) for 5 days at 26°C,140 rpm. Ten wounded roots were immersed in a conidial suspension (2 × 105 conidia/ml) for four hours in a plastic bucket, and planted in five containers (two roots per container) filled with sterile soil. Another ten wounded roots were immersed in sterilized distilled water and planted in five containers as controls. The containers were incubated for four weeks in a greenhouse at temperature between 23°C and 26°C, under a 12-hr light and dark regime, and irrigate with sterile water every 4 days. Three weeks after inoculation, all inoculated plants exhibited chlorotic leaves, wilting and root rot. The taproot and the fibrous roots showed brown to black root rot and no symptoms in non-inoculated controls. The fungus was reisolated from the inoculated plants, but not from any of the control plants. The experiment was repeated two times with similar results. This is the first report of root rot caused by F. commune on American ginseng in China. The disease might bring a threat to this ginseng production and should be implemented effective control measures to reduce losses.

Drought Resistance and Ginsenosides Biosynthesis in Response to Abscisic Acid in Panax ginseng C. A. Meyer.

Drought stress adversely affects the production of the perennial medicinal herb Panax ginseng C.A. Meyer. Phytohormone abscisic acid (ABA) regulates many processes in plant growth, development, and response to environments. However, whether drought resistance is regulated by ABA in Panax ginseng remains unknown. In this study, we characterized the response of drought resistance to ABA in Panax ginseng. The results showed that the growth retardation and root shrinking under drought conditions in Panax ginseng were attenuated by exogenous ABA application. Spraying ABA was shown to protect the photosynthesis system, enhance the root activity, improve the performance of the antioxidant protection system, and alleviate the excessive accumulation of soluble sugar in Panax ginseng under drought stress. In addition, ABA treatment leads to the enhanced accumulation of ginsenosides, the pharmaceutically active components, and causes the up-regulation of 3-hydroxy-3-methylglutaryl CoA reductase (PgHMGR) in Panax ginseng. Therefore, this study supports that drought resistance and ginsenosides biosynthesis in Panax ginseng were positively regulated by ABA, providing a new direction for mitigating drought stress and improving ginsenosides production in the precious medicinal herb.

Bacillus amyloliquefaciens FG14 as a potential biocontrol strain against rusty root rot of Panax ginseng, and its impact on the rhizosphere microbial community

Rusty root rot is the most destructive disease in ginseng production. The bacterial strain FG14 isolated from the rhizosphere of Panax ginseng was characterised as Bacillus amyloliquefaciens. The inhibition rates of the FG14 bacterial suspension against the mycelial growth, spore production and spore germination of Ilyonectria robusta which causes ginseng rusty root rot were all more than 90% at a concentration of 108 cfu/mL. The sterile fermentation broth of strain FG14 also had significant inhibitory ability. The results of plantgrowth promotion showed that the fresh weight and root length of ginseng seedlings treated with 3 × 108 cfu/mL FG14 bacterial suspension were 4.49 times and 2.12 times greater than the seedlings treated with I. robusta. The soil enzyme activities of urease, phosphatase, invertase, and catalase of strain FG14 and the expression of seven lipopeptide biosynthesis genes were up-regulated, and antifungal metabolite production was stable. The diversity and abundance of bacterial and fungal communities in rhizosphere soil changed during different growth stages of ginseng after inoculation with strain FG14. The relative abundance of the Ilyonectria genus was significantly lower than the water control at the leaf spreading stage of P. ginseng. These results indicate the great potential of B. amyloliquefaciens FG14 for use as a biological agent for the green control of ginseng rusty root rot.

Diversity of Fungal Endophytes in American Ginseng Seeds.

Seeds play a critical role in the production of American ginseng. Seeds are also one of the most important media for the long-distant dissemination and the crucial way for pathogen survival. Figuring out the pathogens carried by seeds is the basis for effective management of seedborne diseases. In this paper, we tested the fungi carried by the seeds of American ginseng from the main production areas of China using incubation and highly throughput sequencing methods. The seed-carried rates of fungi in Liuba, Fusong, Rongcheng, and Wendeng were 100, 93.8, 75.2, and 45.7%, respectively. Sixty-seven fungal species, which belonged to 28 genera, were isolated from the seeds. Eleven pathogens were identified from the seed samples. Among the pathogens, Fusarium spp. were found in all of the seed samples. The relative abundance of Fusarium spp. in the kernel was higher than that in the shell. Alpha index showed that the fungal diversity between seed shell and kernel differed significantly. Nonmetric multidimensional scaling analysis revealed that the samples from different provinces and between seed shell and kernel were distinctly separated. The inhibition rates of four fungicides to seed-carried fungi of American ginseng were 71.83% for Tebuconazole SC, 46.67% for Azoxystrobin SC, 46.08% for Fludioxonil WP, and 11.11% for Phenamacril SC. Fludioxonil, a conventional seed treatment agent, showed a low inhibitory effect on seed-carried fungi of American ginseng.

Effects of soil moisture on plant growth and ginsenoside production of Panax ginseng C.A.Meyer

Effects of soil moisture on plant growth and ginsenoside production of Panax ginseng C.A.Meyer

The potential of novel bacterial isolates from healthy ginseng for the control of ginseng root rot disease (Fusarium oxysporum).

Ginseng root rot caused by Fusarium oxysporum is serious disease that impacts ginseng production. In the present study, 145 strains of bacteria were isolated from the rhizosphere soil of healthy ginseng plants. Three strains with inhibitory activity against Fusarium oxysporum (accession number AF077393) were identified using the dual culture tests and designated as YN-42(L), YN-43(L), and YN-59(L). Morphological, physiological, biochemical, 16S rRNA gene sequencing and phylogenetic analyses were used to identify the strains as Bacillus subtilis [YN-42(L)] (accession number ON545980), Delftia acidovorans [YN-43(L)] (accession number ON545981), and Bacillus polymyxae [YN-59(L)] (accession number ON545982). All three isolates effectively inhibited the growth of Fusarium oxysporum in vitro and the antagonistic mechanism used by the three strains involved the secretion of multiple bioactive metabolites responsible for the hydrolysis of the fungal cell wall. All three biocontrol bacteria produce indoleacetic acid, which has a beneficial effect on plant growth. From our findings, all three antagonistic strains can be excellent candidates for ginseng root rot caused by the pathogenic fungus Fusarium oxysporum. These bacteria have laid the foundation for the biological control of ginseng root rot and for further research on the field control of ginseng pathogens.

Influence of volume medium on growth and ginsenoside level in adventitious root culture of Panax ginseng CA Meyer

Ginseng (Panax ginseng, Family Araliaceae) is a traditional herbal plant that is pretty well known and has been widely used in various countries, such as Korea, China, and Japan. Ginseng contains ginsenoside secondary metabolites that have been shown to have therapeutic effects, such as antioxidant, anti-inflammatory, anti-allergic, anti-diabetic, and anti-cancer. Ginseng production by traditional cultivation methods is long and produces inconsistent results. Therefore, in vitro culture is an alternative method to produce ginseng and ginsenoside consistently. In 2018, PT Bintang Todjoe collaborated with the University of Surabaya (UBAYA) and the Hanbang-Bio Inc. (holding company of Kyung Hee University) to establish the Kalbe Ubaya Hanbang-Bio Laboratory (KUH Lab). From previous studies, the dry weight achieved was only 109.758 g, which did not reach the target (120 grams). Therefore, the media was modified by adding media volume from 13L to 15L. The increase in media volume increased fresh weight to 2728.7 g, dry weight to 137.6 g, and yield up to 5%. However, this increase in media volume has not increased ginsenoside levels.

The Rhizosphere Microbiome of Ginseng.

The rhizosphere of ginseng contains a wide range of microorganisms that can have beneficial or harmful effects on the plant. Root exudates of ginseng, particularly ginsenosides and phenolic acids, appear to select for particular microbial populations through their stimulatory and inhibitory activities, which may account for the similarities between the rhizosphere microbiomes of different cultivated species of Panax. Many practices of cultivation attempt to mimic the natural conditions of ginseng as an understory plant in hilly forested areas. However, these practices are often disruptive to soil, and thus the soil microbiome differs between wild and cultivated ginseng. Changes in the microbiome during cultivation can be harmful as they have been associated with negative changes of the soil physiochemistry as well as the promotion of plant diseases. However, isolation of a number of beneficial microbes from the ginseng rhizosphere indicates that many have the potential to improve ginseng production. The application of high-throughput sequencing to study the rhizosphere microbiome of ginseng grown under a variety of conditions continues to greatly expand our knowledge of the diversity and abundance of those organisms as well as their impacts of cultivation. While there is much more to be learnt, many aspects of the ginseng rhizosphere microbiome have already been revealed.

Occurrence of Sclerotinia sclerotiorum Causing Sclerotinia Root Rot onAmerican Ginseng in Northeastern China.

American ginseng (Panax quinquefolium) is a valuable medicinal plant that is commercially cultivated in China. In May 2020, Sclerotinia root rot of American ginseng was observed on 4-year-old plants in Fusong County in northeastern China, which is the most important part of the country for American ginseng cultivation. The pathogen only infected the tuberous ginseng roots, with sclerotia tightly attached to the root surface. Infected roots, which were brownish and had a watery soft rotted appearance (Fig. 1), eventually became hollow and filled with sclerotia. There were no significant changes to the aboveground plant parts during the initial infection stage, but as the disease progressed, the foliage became discolored and wilted because of the damaged roots. More than 31% of the plants in a 30-ha field were infected. Symptomatic roots were collected and sclerotia were removed from the diseased tissue, immersed in 1% NaClO for 1 min, rinsed three times with sterile water, and placed on acidified potato dextrose agar (PDA) in Petri dishes. After an incubation in darkness at 20 °C for 2-3 days, 21 suspected Sclerotinia isolates were obtained. Isolates JH1 and JH2 were randomly selected for identification. On PDA, colonies produced sparse, white, and cottony aerial mycelia (i.e., wool-like appearance), with septate, branched, and hyaline hyphae. Within 4 days of incubation, the PDA surface was covered with white hyphae. Small and white sclerotial primordia formed 3 days later and were irregularly distributed in the middle and along the edge of the Petri dish. After maturing, the hardened and black sclerotia had an irregular shape and size, ranging from 1.4 × 1.5 to 4.1 × 7.5 mm (n = 50). Most of the sclerotia developed separately, with approximately 15-25 per plate (Fig. 2). On the basis of their morphology, the isolates were initially identified as Sclerotinia sp. (Mordue and Holliday 1976; Kohn 1979). Using the JH1 and JH2 rDNA internal transcribed spacer (ITS) region (GenBank accession no. MZ031405 and MZ031406) and the aspartyl protease gene specific to S. sclerotiorum (MZ292709 and MZ292710) in GenBank as queries, BLAST searches revealed that the sequences were respectively 99%-100% similar to S. sclerotiorum sequences KF859933 and AF271387. The primer pairs for amplifying the ITS region and the aspartyl protease gene were respectively ITS4/ITS5 (White et al. 1990) and SSaspr F/SSaspr R (Abd-Elmagid et al. 2013). The pathogenicity of JH1 and JH2 was evaluated using healthy plants. The roots of 4-year-old ginseng plants were washed, wiped with 75% alcohol, and transferred to flower pots containing sterile sand and sorghum grain (10:1 v/v) infested with 10-day-old isolates. For both isolates, 12 plants were inoculated, with four plants per pot. Control plants were transferred to flower pots containing sorghum grain lacking fungus. The inoculated samples were incubated in a greenhouse (12 h photoperiod and 25 °C) for 25 days before they were examined. The test was repeated twice. The inoculated roots exhibited the same symptoms as those observed in the field, whereas the controls remained symptomless. The same fungus was reisolated from all infected roots and resequencing results confirmed its identity. To the best of our knowledge, this is the first report of S. sclerotiorum causing Sclerotinia root rot on American ginseng in China. Because this disease is detrimental to the production of American ginseng, effective management strategies will need to be developed.

Economic Analysis of Ginseng Based Forest Farming: a Sustainable Income Diversification Opportunity for Forest Landowners

While American ginseng is a complicated opportunity for forest farmers to understand, within these production systems there are many opportunities and constraints linked to production of ginseng. There are different market demands and prices paid for the various grades of dried roots depending on the system used to cultivate the plant. This study reviewed the unique benefits of producing ginseng, opportunities for forest farmers, the potential profits, as well as financial risks. The study focused on two common ginseng production systems in the southeastern region of the U.S. The specific objective of the paper is to assess economic returns of producing ginseng under different production systems. The Monte Carlo simulation was performed to analyze the profitability and risks associated with producing ginseng and performed sensitive analysis to determine the effect of uncertainty variables such as production costs, yield, and price of product on economic feasibility.

Integrative analysis of multiple metabolomes and transcriptome revealed color expression mechanism in red skin root syndrome of Panax ginseng

Red skin root syndrome causes reduction of both production and quality of Panax ginseng (ginseng). However, its development process and key metabolites are still unknown. Multiple metabolomes including non-targeted metabolome, and anthocyanins-targeted and carotenoids-targeted metabolomes were performed on field grown red skin and healthy ginseng. The detected metabolites were analyzed in combination with previous transcriptome results. The total metabolite profiles revealed that primary metabolites especially citrate was decreased, but secondary metabolites mainly involved in phenylpropanoid pathway were increased in red skin ginseng compared to those in healthy ginseng. Targeted metabolome found that each gram of fresh red skin ginseng sample contained 8 μg β-carotene, 0.56 μg α-carotene, 0.017 μg rutin, 0.248 μg chalcone, and some anthocyanins including 0.023 μg cyanidin and 0.037 μg quercetin 3-O-glucoside, albeit in low concentrations but higher than those in healthy ginseng. Furthermore, integrative metabolome and transcriptome analysis revealed that changes of metabolites related to anthocyanins synthesis were correlated with the related gene expression patterns. Additionally, jasmonate (JA) and its precursor 12-oxophytodienoic acid increased their concentrations dramatically in red skin ginseng, suggesting the possible role of JA or JA signaling pathway in regulating red skin syndrome. Consistently, the expressions of 17 MYB transcription factors were differentially regulated in red skin ginseng. JA related cis-elements are widely distributed at their promoters. Taken together, our study revealed reduction of primary metabolism but increase of secondary metabolism in red skin ginseng. MYB transcription factors of JA signal pathway were supposed to mediate accumulation of anthocyanins and carotenoids that contributed to the development of red skin ginseng.

Improved ginseng production under continuous cropping through soil health reinforcement and rhizosphere microbial manipulation with biochar: a field study of Panax ginseng from Northeast China.

ABSTRACTThe production of ginseng, an important Chinese medicine crop, has been increasingly challenged by soil degradation and pathogenic disease under continuous cropping in Northeast China. In a field experiment, an Alfisol garden continuously cropped with Chinese ginseng (Panax ginseng C. A. Meyer) was treated with soil amendment at 20 t ha−1 with maize (MB) and wood (WB) biochar, respectively, compared to conventional manure compost (MC). Two years after the amendment, the rooted topsoil and ginseng plants were sampled. The changes in soil fertility and health, particularly in the soil microbial community and root disease incidence, and in ginseng growth and quality were portrayed using soil physico-chemical assays, biochemical assays of extracellular enzyme activities and gene sequencing assays as well as ginsenoside assays. Topsoil fertility was improved by 23% and 39%, ginseng root biomass increased by 25% and 27%, and root quality improved by 6% and 18% with WB and MB, respectively, compared to MC. In the ginseng rhizosphere, fungal abundance increased by 96% and 384%, with a significant and insignificant increase in bacterial abundance, respectively, under WB and MB. Specifically, the abundance of Fusarium spp. was significantly reduced by 19–35%, while that of Burkholderia spp. increased by folds under biochar amendments over MC. Relevantly, there was a significant decrease in the abundance proportion of pathotrophic fungi but a great increase in that of arbuscular mycorrhizal fungi, along with an enhanced microbial community network complexity, especially fungal community complexity, under biochar amendments. Thus, biochar, particularly from maize residue, could promote ginseng quality production while enhancing soil health and ecological services, including carbon sequestration, in continuously cropped fields.

Occurrence of postharvest snow rot caused by Sclerotinia nivalis on Asian ginseng in China.

Asian ginseng (Panax ginseng) is a valuable medicinal plant that is commercially cultivated in China. A long postharvest storage period is required before ginseng is processed. From October 2019 to May 2020, snow rot was observed on the roots of 4- and 5-year-old fresh ginseng stored in three cold storage facilities located in Tonghua and Changbai cities in northeastern China, which are the most important regions for Asian ginseng production. We sampled 1,000 ginseng roots from the three cold storage facilities, and the average disease incidence was 21%. Initially, sparse hyphae and microsclerotia appeared on the root epidermis. Lesions gradually softened and the epidermis detached easily. Multiple infected sites slowly converged, resulting in the formation of a dense complex of multiple sclerotia and thick hyphae on the surface of the ginseng root as well as internal decay. The infection eventually spread to the adjacent ginseng roots (Fig. 1). Sixteen diseased ginseng roots were collected and then sclerotia were removed from the root surface, immersed in 1% NaClO for 2 min, rinsed three times with sterile water, and placed on potato dextrose agar (PDA) containing streptomycin (40 μg/mL) in Petri dishes. After a 3-day incubation at 20 °C in darkness, 22 suspected Sclerotinia isolates were obtained. Isolates SN1 and SN2 were randomly selected for identification. On PDA, fast-growing colonies produced white, sparse, powdery, and cotton-like aerial mycelia, and the reverse side showed the same color (Fig. 2). Small and white sclerotial primordia formed 3 days later and a ring of sclerotia was detected at the plate periphery. At 7 to 10 days after incubation, the mature sclerotia were black, spherical-to-subspherical, and elongated or fused to form irregular shapes. Each Petri dish produced 55-65 sclerotia, measuring 1.1 × 1.2 to 3.2 × 3.9 mm (n = 100). The sclerotia were firmly attached to the agar surface. The isolates were initially identified as Sclerotinia sp. (Saito 1997). After sequencing the nuclear ribosomal internal transcribed spacer region (MW927134 and MW927135) and the β-tubulin gene (MW929179 and MW929180) (White et al. 1990; Glass and Donaldson 1995), BLAST searches revealed 100% homology with JX262268 and JX296007 of the published S. nivalis strain KGC-S0601, respectively. The pathogenicity of the two isolates was tested using detached ginseng roots. Briefly, healthy roots were washed, surface-disinfested with 75% alcohol, and rinsed with sterile water. Mycelial plugs (5 mm diameter) removed from the margin of actively growing colonies on PDA were placed on the ginseng roots. For each isolate, four roots were inoculated, with two plugs per root. Additionally, PDA plugs without mycelia were used as the negative control. The roots were placed in a fresh-keeping box at 20 °C in darkness and evaluated after 7 days. The pathogenicity test was repeated twice. The symptoms on the inoculated roots were the same as those observed on the roots during cold storage, whereas the control roots remained symptomless. The same fungus was reisolated consistently from all infected roots and its identity was confirmed by resequencing, thereby fulfilling Koch's postulates. To the best of our knowledge, this is the first report of S. nivalis causing postharvest snow rot on Asian ginseng in China. The occurrence of this disease threatens the postharvest storage of Asian ginseng. Hence, effective management strategies must be developed.

Investigating the effect of microbial inoculants Frankia F1 on growth-promotion, rhizosphere soil physicochemical properties, and bacterial community of ginseng

Ginseng root rot caused by Fusarium solani (F. solani) is a highly destructive soil-borne disease that happens worldwide, which seriously affects the growth and development of many types of crops. Frankia casuarinae CcI3 (Frankia F1) microbial inoculants F1 on the mycelial integrity of pathogenic fungus F. solani, the growth of ginseng plants, and the structure of rhizosphere microbial community were carefully studied in the rhizosphere soil of ginseng infected with ginseng disease. Under the normal ginseng growth and F. solani infected environment, plant height, root length, dry weight, stem diameter, leaf area, and chlorophyll content increased by 40.57%, 68.98%, 92.09%, 56.67%, 23.29%, and 39.60% in T2 (50 mL microbial inoculants F1) compared with CK (natural control without treatment). Increased enzyme activity of phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), β-1, 3-glucanase, and chitinase showed improved disease resistance and stress resistance of plants in ginseng leaves having inoculation. Our present study demonstrated that the soil pH value, cation exchange capacity, organic matter, total nitrogen, available nitrogen, phosphorus, and potassium increased by 8.00%, 50.78%, 18.81%, 43.36%, 23.25%, 14.00%, and 5.11% in T2 compared with CK. Furthermore, the soil enzyme activities of catalase, sucrase, and urease in T2 treatment were increased by 12.14%, 27.56%, and 22.60%, respectively. Amplicon sequencing analysis revealed that the diversity of soil bacteria decreased after microbial inoculants F1 treatment. More specifically, the T2 treatment inhibited the growth of F. solani, and promoted that the relative abundance of Xanthomonadales, Sphingomonadales, Sphingobacteriales, Frankiales, and Propionibacteriales. The PICRUSt data predicted an array of bacterial functions, and microbial inoculants F1 primarily increased the abundance of functional genes related to bacterial metabolism in ginseng soil we confirmed. Collectively, we found that the optimal inoculation amount of Frankia F1 for inhibiting F. solani and promoting the growth of ginseng plants was 50 mL (T2), which could effectively regulate the soil microbial community structure during ginseng production. It helped to promote the sustainable development of Chinese agriculture.