An investigation of Panax ginseng Meyer growth promotion and the biocontrol potential of antagonistic bacteria against ginseng black spot

ApWD40a, a Member of the WD40-Repeat Protein Family, Is Crucial for Fungal Development, Toxin Synthesis, and Pathogenicity in the Ginseng Alternaria Leaf Blight Fungus Alternaria panax

Alternaria panax, the primary pathogen that causes ginseng Alternaria leaf blight disease, can lead to a 20-30% reduction in ginseng yield. WD40 repeat-containing proteins are evolutionarily conserved proteins with diverse functions between different organisms. In this study, we characterized the roles of a WD40 repeat-containing protein in A. panax. The deletion of ApWD40a impaired the mycelial growth, reduced the sporulation, and significantly decreased the efficiency in utilizing various carbon sources. The ΔApwd40a mutant showed increased sensitivity to osmotic stress and metal ion stress induced by sorbitol, NaCl, and KCl, but decreased the sensitivity to a cell wall stress factor (SDS) and oxidative stress factors (paraquat and H2O2). Pathogenicity assays performed on detached ginseng leaves and roots revealed that the disruption of ApWD40a significantly decreased the fungal virulence through attenuating melanin and mycotoxin production by A. panax. A comparative transcriptome analysis revealed that ApWD40a was involved in many metabolic and biosynthetic processes, including amino acid metabolism, carbon metabolism, sulfate metabolic pathways, and secondary metabolite pathways. In particular, a significantly upregulated gene that encoded a sulfate permease 2 protein in ΔApwd40a, named ApSulP2, was deleted in the wild-type strain of A. panax. The deletion of ApSulP2 resulted in reduced biomass under sulfate-free conditions, demonstrating that the sulfate transport was impaired. Taken together, our findings highlight that ApWD40a played crucial roles in different biological processes and the pathogenicity of A. panax through modulating the expressions of genes involved in various primary and secondary metabolic processes.

Understanding the Pathogenesis, Biocontrol Mechanisms, and Factors Influencing Biocontrol Effectiveness for Soil-Borne Diseases in Panax Plants

Panax plants are known for their significant medicinal and economic value. Being perennial, they are prone to soil-borne diseases during cultivation. However, there has been limited research on the pathogenesis of soil-borne diseases and the diversity of pathogens. While biological control has gained attention for its efficacy and environmental benefits, the factors affecting its efficiency still need thorough evaluation. This review summarizes the influence of biotic factors, such as pathogens and hosts, and environmental factors on the occurrence of soil-borne diseases and pathogen diversity. Additionally, we synthesized bacterial, actinobacterial, and fungal diversity for the biocontrol of soil-borne diseases and their functional mechanisms. Moreover, the review delves into the factors influencing the efficacy of biocontrol, including microbial species, the inoculation method and inoculation volume, and inoculant composition. This article serves as a valuable resource for enhancing the efficiency of biological control and optimizing strategies for managing soil-borne diseases in Panax cultivation in the future.

Application of microorganisms in Panax ginseng: cultivation of plants, and biotransformation and bioactivity of key component ginsenosides

Panax ginseng is a precious Chinese medicinal plant with a long growth cycle and high medicinal value. Therefore, it is of great significance to explore effective ways to increase its yield and main active substance content to reduce the cost of ginseng, which is widely used in food and clinical applications. Here, we review the key roles of microorganisms in the biological control of ginseng diseases, enhancement of ginseng yield, biotransformation of ginsenosides, and augmentation of ginsenoside bioactivity. The application of microorganisms in P. ginseng faces multiple challenges, including the need for further exploration of efficient microbial strain resources used in the cultivation of ginseng and biotransformation of ginsenosides, lack of microbial application in large-scale field cultivation of ginseng, and unclear mechanism of microbial transformation of ginsenosides. This review provides a deeper understanding of the applications of microorganisms in P. ginseng.

Bacillus velezensis B105-8, a potential and efficient biocontrol agent in control of maize stalk rot caused by Fusarium graminearum

Introduction

Maize stalk rot (MSR), caused by Fusarium graminearum, is the most serious soil borne disease in maize production, seriously affecting maize yield and quality worldwide. Microbial biocontrol agents are the best means of controlling MSR and reducing the use of chemical fungicides, such as Bacillus spp.

Methods and results

In the study, a soil-isolated strain B105-8 was identified as B. velezensis (accession No. PP325775.1 and No. PP869695.1), demonstrated a broad spectrum against various pathogens causing maize diseases, which effectively controlled MSR, exhibited a high control efficacy of more than 60% and growth-promoting effect in the pot plant. B105-8 could effectively improve soil urease (S-UE), invertase (S-SC), and catalase (S-CAT) activities. S-NP activity showed an initial increase with a peak of 20,337 nmol/h/g, followed by a decrease, but activity remained significantly better than control treatment with chemical fungicides. The application of B105-8 repaired the damage caused by F. graminearum on soil activity. The antifungal compound B-1, extracted from B105-8, was purified using a protein purifier, revealing inhibitory effects against F. graminearum. Mass spectrometry analysis indicated the potential presence of C14 Bacillomycin, C15 Iturin, C15 Mycosubtilin, C17, and C15 fengycin in B-1. In pot experiments, a 5 μL/mL concentration of B-1 exhibited 69% control on MSR, enhancing maize root elongation, elevation, and fresh weight. At 10 μL/mL, B-1 showed 89.0 and 82.1% inhibition on spore production and mycelial growth, causing hyphal deformities.

Discussion

This study presents the innovative use of B. velezensis, isolated from maize rhizosphere in cold conditions to effectively control MSR caused by F. graminearum. The findings highlight the remarkable regional and adaptive characteristics of this strain, making it an excellent candidate to fight MSR in diverse environments. In conclusion, B. velezensis B105-8 demonstrated potential as a biocontrol agent for MSR.

Biocontrol of rusted root rot in Panax ginseng by a combination of extracts from Bacillus amyloliquefaciens YY8 crude protein and Enterobacteriaceae YY115 ethyl acetate

BACKGROUND

Rusted root rot is one of the most common root diseases in Panax ginseng, and Cylindrocarpon destructans is one of the main pathogenic fungus. The objective of this study was to screen and explore the extracts of biocontrol bacteria isolated from ginseng rhizosphere soil against Cylindrocarpon destructans.

RESULTS

Bacterial strains Bacillus amyloliquefaciens YY8 and Enterobacteriacea YY115 were isolated and found to exhibit in vitro antifungal activity against C. destructans. A combination of crude protein extract from B. amyloliquefaciens YY8 and ethyl acetate extract from Enterobacteriacea YY115 in a 6:4 ratio exhibited the strongest antifungal activity against C. destructans. Measurements of electrical conductivity, protein content, and nucleic acid content in suspension cultures of C. destructans treated with a mixture extracts indicated that the extracts disrupted the cell membranes of rusted root rot mycelia, resulting in the leakage of electrolytes, proteins, and nucleic acids from the cells, and ultimately inhibiting the growth of C. destructans. The combined extracts suppressed the infection of ginseng roots discs by C. destructans effectively.

CONCLUSION

The extracts obtained from the two bacterial strains effectively inhibited C. destructans in P. ginseng. It can provide scientific basis for the development of new biological control pesticides, reduce the use of chemical pesticides, and promote the sustainable development of agriculture.

Newly isolated Brevundimonas naejangsanensis as a biocontrol agent against Fusarium redolens the causal of Fusarium yellows of chickpea

Three endophytic bacteria, namely BvV, BvP and BvL, were newly isolated from the root nodules of bean, pea and lentil plants respectively cultivated in Mascara the northwest of Algeria, and identified by 16S ribosomal RNA gene sequencing as Brevundimonas naejangsanensis. These strains were able to produce hydrolytic enzymes and hydrogen cyanide. All strains produced a growth-promoting hormone, indole acetic acid, varying in concentration from 83.2 to 171.7 µg/mL. The phosphate solubilizing activity of BvV, BvP and BvL varied from 25.5 to 42.02 µg/mL for tricalcium phosphate. The three antagonistic Brevundimonas spp. showed in vitro the most inhibitory effect on mycelial growth of Fusarium redolens FRC (from 78.33 to 85.55%). Strain BvV, BvP and BvL produced also volatile metabolites which inhibited mycelial FRC growth up to 39.2%. All strains showed significant disease reduction in pot experiments. Chickpea Fusarium yellows severity caused by FRC was reduced significantly from 89.3 to 96.6% in the susceptible cultivar ILC 482 treated with antagonistic B. naejangsanensis. The maximum stimulatory effect on chickpea plants growth was observed by inoculation of strain BvV. This treatment resulted in a 7.40-26.21% increase in shoot height as compared to the control plants. It is concluded that the endophytic bacterial strains of B. naejangsanensis having different plant growth promoting (PGP) activities can be considered as beneficial microbes for sustainable agriculture. To our knowledge, this is the first report to use B. naejangsanensis strains as a new biocontrol agent against F. redolens, a new pathogen of chickpea plants causing Fusarium yellows disease in Algeria.

Recent trends in ginseng research

Ginseng, the dried root of Panax ginseng, contains ginsenosides and has long been used in Korea, China, and Japan to treat various symptoms. Many studies on the utility of ginseng have been conducted and in this paper we investigate recent trends in ginseng research. P. ginseng studies were collected from scientific databases (PubMed, Web of Science, and SciFindern) using the keywords "Panax ginseng C.A. Meyer", "ginsenosides", "genetic diversity", "biosynthesis", "cultivation", and "pharmacology". We identified 1208 studies up to and including September 2023: 549 studies on pharmacology, 262 studies on chemical components, 131 studies on molecular biology, 58 studies on cultivation, 71 studies on tissue culture, 28 studies on clinical trials, 123 reviews, and 49 studies in other fields. Many researchers focused on the characteristic ginseng component ginsenoside to elucidate the mechanism of ginseng's pharmacological action, the relationship between component patterns and cultivation areas and conditions, and gene expression.

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.

Transcriptome and metabolite analyses indicated the underlying molecular responses of Asian ginseng (Panax ginseng) toward Colletotrichum panacicola infection

Panax ginseng Meyer is one of the most valuable plants and is widely used in China, while ginseng anthracnose is one of the most destructive diseases. Colletotrichum panacicola could infect ginseng leaves and stems and causes serious anthracnose disease, but its mechanism is still unknown. Here, transcriptome and metabolism analyses of the host leaves were conducted to investigate the ginseng defense response affected by C. panacicola. Upon C. panacicola infection, ginseng transcripts altered from 14 to 24 h, and the expression of many defense-related genes switched from induction to repression. Consequently, ginseng metabolites in the flavonoid pathway were changed. Particularly, C. panacicola repressed plant biosynthesis of the epicatechin and naringin while inducing plant biosynthesis of glycitin, vitexin/isovitexin, and luteolin-7-O-glucoside. This work indicates C. panacicola successful infection of P. ginseng by intervening in the transcripts of defense-related genes and manipulating the biosynthesis of secondary metabolites, which might have antifungal activities.

IAA and ACC deaminase producing-bacteria isolated from the rhizosphere of pineapple plants grown under different abiotic and biotic stresses

The roles of plant growth-promoting rhizobacteria in promoting plant growth and soil health, including alteration in plant metabolism and production of phytohormones such as indole-3-acetic acid (IAA) and the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, are indisputable. This study aimed to isolate and characterize beneficial bacteria isolated from the rhizosphere of pineapple from distinct stress-inducing habitats, including water excess-, herbicide-over-treated-, and pathogen-infected areas at PT Great Giant Foods located in Lampung, Indonesia. The isolated bacteria were screened based on IAA production and ACC deaminase activities. Six selected isolates produced IAA with concentrations of up to 36.93 mgL^-1. The highest value belongs to Bacillus sp. NCTB5I, followed by Brevundimonas sp. CHTB 2C (13.13 mgL^-1) and Pseudomonas sp. CHTB 5B (6.65 mgL^-1). All isolates were detected with ACC deaminase activities with Brevundimonas sp. CHTJ 5H consuming 88% of ACC over 24 h, the highest among all. Brevundimonas sp. CHTB 2C was detected with the highest ACC deaminase activity with the value of 13,370 nm α-ketobutyrate mg^-1h^-1. In another experiment, it was revealed that all selected isolates promote soybean growth. These bacteria are potential to be developed in the future as bioagents to promote plant growth, especially under stressful environmental conditions.

Diversity and characterization of antagonistic bacteria against Pseudomonas syringae pv. actinidiae isolated from kiwifruit rhizosphere

Kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) is a severe global disease. However, effective biological control agents for controlling Psa are currently unavailable. This study aimed to screen potential biological control agents against Psa from the kiwifruit rhizosphere. In this study, a total of 722 isolates of bacteria were isolated from the rhizosphere of kiwifruit orchards in five regions of China. A total of 82 strains of rhizosphere bacteria showed antagonistic effects against Psa on plates. Based on amplified ribosomal DNA restriction analysis (ARDRA), these antagonistic rhizosphere bacteria were grouped into 17 clusters. BLAST analyses based on 16S rRNA gene sequence revealed 95.44%-100% sequence identity to recognized species. The isolated strains belonged to genus Acinetobacter, Bacillus, Chryseobacterium, Flavobacterium, Glutamicibacter, Lysinibacillus, Lysobacter, Pseudomonas, Pseudarthrobacter, and Streptomyces, respectively. A total of four representative strains were selected to determine their extracellular metabolites and cell-free supernatant activity against Psa in vitro. They all produce protease and none of them produce glucanase. One strain of Pseudomonas sp. produces siderophore. Strains of Bacillus spp. and Flavobacteria sp. produce cellulase, and Flavobacteria sp. also produce chitinase. Our results suggested that the kiwifruit rhizosphere soils contain a variety of antagonistic bacteria that effectively inhibit the growth of Psa.

Potential of Medicago sativa and Perilla frutescens for overcoming the soil sickness caused by ginseng cultivation

There are serious soil sickness in ginseng cultivation. Crop rotation is an effective agricultural management to improve soil sustainability and reduce soil sickness. To explore an appropriate ginseng rotation system, Medicago sativa (alfalfa) and Perilla frutescens (perilla) were planted on ginseng cultivation soil for 1 year to evaluate the improvement effect of both. Through chemical analysis and high-throughput sequencing technology, we found that after alfalfa and perilla cultivation for one-year, various nutrients and enzyme activities in ginseng cultivation soil were significantly improved. In addition, perilla significantly increased the diversity and richness of soil fungal communities. Cultivation of alfalfa and perilla significantly changed the composition of soil bacterial and fungal communities and significantly reduced the abundance of the potentially pathogenic fungi Ilyonectria. Further pot experiments also showed that the improved soil could significantly increase root activity of ginseng plant after two plants were planted. It should be noted that, unlike alfalfa, perilla decreased soil electrical conductivity, increased soil organic matter, soil urease, and may significantly improve the diversity and richness of soil fungal community. Moreover, in the pot experiment, the root fresh weight of ginseng cultured in perilla treated soil increased significantly. This study highlights that perilla may have better soil improvement effect than alfalfa and it has the potential to be used in the soil improvement of ginseng cultivation.

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.

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.

A Novel Biocontrol Strain Bacillus amyloliquefaciens FS6 for Excellent Control of Gray Mold and Seedling Diseases of Ginseng

The biocontrol efficacy of Bacillus amyloliquefaciens FS6 against seedling diseases and gray mold of ginseng (Panax ginseng), as well as application techniques, were evaluated in a series of field trials. FS6 fermentation broth showed a strong antagonistic effect against the ginseng fungal pathogens, and the inhibition rates on mycelial growth and spore germination were 84 to 88% and 71 to 72%, respectively. Field evaluation showed that combination of seed and soil treatments exhibited better protection than that of individual treatment alone. FS6 wettable powder soil treatment in combination with thiamethoxam plus metalaxyl-M plus fludioxonil for seed coating performed the best, with >83% overall control efficacy for seedling diseases. FS6 had a long-acting effect of >78% control efficacy on ginseng gray mold at 30 days after the last application, almost 2.5- and 2-fold better than that of B. amyloliquefaciens B7900 wettable powder and cyprodinil, respectively. In addition, FS6 reduced the diversity and relative abundance of fungi and affected the fungi and bacterial composition in the rhizosphere soil of ginseng. Therefore, FS6 can be used to effectively control seedling diseases and gray mold in ginseng.

An LCI-like protein APC2 protects ginseng root from Fusarium solani infection

AIMS

We aimed to purify an antimicrobial protein from Bacillus amyloliquefaciens FS6 culture supernatant, verify its antimicrobial activity against Fusarium solani and evaluate its biocontrol potential for ginseng root rot.

METHODS AND RESULTS

The antimicrobial protein was purified from FS6 culture supernatant using ammonium sulphate precipitation, anion exchange and gel chromatography. Based on mass spectrometry results, the purified protein was identified as an antimicrobial protein of the LCI family and was designated APC₂ . The APC₂ recombinant protein expressed in Escherichia coli (BL21) significantly inhibited F. solani and decreased the infection and spread of F. solani in ginseng root. An overexpressing APC₂ strain FS6-APC₂ was constructed and shown to have enhanced antimicrobial activity compared to the wild-type strain FS6.

CONCLUSIONS

The APC₂ protein shows strong antimicrobial activity against F. solani, reduces the incidence and severity of ginseng root rot caused by F. solani and exhibits a great biocontrol potential.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reports the inhibitory activity of APC₂ protein (LCI family) against F. solani and its protective efficacy on ginseng root rot. These findings provide a scientific basis for future research on the biocontrol mechanism, as well as the development and application of FS6.

Chlamydomonas reinhardtii Exhibits De Facto Constitutive NPQ Capacity in Physiologically Relevant Conditions

The photosynthetic apparatus must be able to withstand light conditions that exceed its capacity for carbon fixation. Photosynthetic organisms developed nonphotochemical quenching (NPQ), a process that dissipates excess absorbed light energy as heat and limits the production of reactive oxygen species and cellular damage. In the green alga Chlamydomonas reinhardtii, the LHCSR pigment-binding proteins are essential for NPQ. These complexes are not constitutively present in the thylakoid membranes; however, in laboratory conditions their expression depends on prior high light exposure of cells. To investigate the role of NPQ, we measured cells grown under a day-night cycle with a high light peak at mid-day. LHCSRs are present and NPQ is active consistently throughout the day, likely due to their slow degradation in vivo. This suggests that in physiologically relevant conditions, Chlamydomonas cells are prepared to immediately activate photoprotection, as is the case in vascular plants. We further reveal that state transitions are fully functional under these conditions and that PsbS is highly expressed throughout the day, suggesting it might have a more impactful role than previously thought.

Inhibitory Effects of Black Ginseng on Particulate Matter-Induced Pulmonary Injury

Inhalation of fine particulate matter (PM2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. Black ginseng (BG), steamed and dried ginseng nine times, exhibits various pharmacological activities such as antibacterial, antihyperglycemic, anti-atopic, antibacterial, and anti-inflammatory activities. In this study, we investigated the beneficial effects of black ginseng extract (BGE) against PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM2.5-treated ECs and mice. BGE significantly scavenged PM2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase (MAPK). Concurrently, BGE activated Akt, which helped maintain endothelial integrity. Furthermore, BGE reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid in PM-induced lung tissues. These results indicated that BGE may exhibit protective effects against PM-induced inflammatory lung injury and vascular hyperpermeability.