Rhizospheric fungi of Panax notoginseng: diversity and antagonism to host phytopathogens

Miao, Cui-Ping,Mi, Qi-Li,Qiao, Xin-Guo,Zheng, You-Kun,Chen, You-Wei,Xu, Li-Hua,Guan, Hui-Lin,Zhao, Li-Xing The Korean Society of Ginseng 2016 Journal of Ginseng Research Vol.40 No.2

Background: Rhizospheric fungi play an essential role in the plantesoil ecosystem, affecting plant growth and health. In this study, we evaluated the fungal diversity in the rhizosphere soil of 2-yr-old healthy Panax notoginseng cultivated in Wenshan, China. Methods: Culture-independent Illumina MiSeq and culture-dependent techniques, combining molecular and morphological characteristics, were used to analyze the rhizospheric fungal diversity. A diffusion test was used to challenge the phytopathogens of P. notoginseng. Results: A total of 16,130 paired-end reads of the nuclear ribosomal internal transcribed spacer 2 were generated and clustered into 860 operational taxonomic units at 97% sequence similarity. All the operational taxonomic units were assigned to five phyla and 79 genera. Zygomycota (46.2%) and Ascomycota (37.8%) were the dominant taxa; Mortierella and unclassified Mortierellales accounted for a large proportion (44.9%) at genus level. The relative abundance of Fusarium and Phoma sequenceswas high, accounting for 12.9% and 5.5%, respectively. In total,113 fungal isolates were isolated from rhizosphere soil. They were assigned to five classes, eight orders (except for an Incertae sedis), 26 genera, and 43 species based on morphological characteristics and phylogenetic analysis of the internal transcribed spacer. Fusarium was the most isolated genus with six species (24 isolates, 21.2%). The abundance of Phoma was also relatively high (8.0%). Thirteen isolates displayed antimicrobial activity against at least one test fungus. Conclusion: Our results suggest that diverse fungi including potential pathogenic ones exist in the rhizosphere soil of 2-yr-old P. notoginseng and that antagonistic isolates may be useful for biological control of pathogens.

Rhizospheric fungi of Panax notoginseng: diversity and antagonism to host phytopathogens

Cui-Ping Miao,Qi-Li Mi,Xin-Guo Qiao,You-Kun Zheng,You-Wei Chen,Li-Hua Xu,Hui-Lin Guan,Li-Xing Zhao 고려인삼학회 2016 Journal of Ginseng Research Vol.40 No.2

Background: Rhizospheric fungi play an essential role in the plantesoil ecosystem, affecting plant growth and health. In this study, we evaluated the fungal diversity in the rhizosphere soil of 2-yr-old healthy Panax notoginseng cultivated in Wenshan, China. Methods: Culture-independent Illumina MiSeq and culture-dependent techniques, combining molecular and morphological characteristics, were used to analyze the rhizospheric fungal diversity. A diffusion test was used to challenge the phytopathogens of P. notoginseng. Results: A total of 16,130 paired-end reads of the nuclear ribosomal internal transcribed spacer 2 were generated and clustered into 860 operational taxonomic units at 97% sequence similarity. All the operational taxonomic units were assigned to five phyla and 79 genera. Zygomycota (46.2%) and Ascomycota (37.8%) were the dominant taxa; Mortierella and unclassified Mortierellales accounted for a large proportion (44.9%) at genus level. The relative abundance of Fusarium and Phoma sequenceswas high, accounting for 12.9% and 5.5%, respectively. In total,113 fungal isolates were isolated from rhizosphere soil. They were assigned to five classes, eight orders (except for an Incertae sedis), 26 genera, and 43 species based on morphological characteristics and phylogenetic analysis of the internal transcribed spacer. Fusarium was the most isolated genus with six species (24 isolates, 21.2%). The abundance of Phoma was also relatively high (8.0%). Thirteen isolates displayed antimicrobial activity against at least one test fungus. Conclusion: Our results suggest that diverse fungi including potential pathogenic ones exist in the rhizosphere soil of 2-yr-old P. notoginseng and that antagonistic isolates may be useful for biological control of pathogens.

Radiosensitivity Enhancement by Arsenic Trioxide in Conjunction with Hyperthermia in the EC-1 Esophageal Carcinoma Cell Line

Cui, Yan-Hui,Liang, Hai-Jun,Zhang, Qing-Qin,Li, Si-Qing,Li, Xiao-Rui,Huo, Xiao-Qing,Yang, Qing-Hui,Li, Wei-Wei,Gu, Jian-Fa,Hua, Qin-Liang,Lu, Ping,Miao, Zhan-Hui Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.4

Objective: To explore the effect on radiosensitivity of arsenic trioxide ($As_20_3$) in conjunction with hyperthermia on the esophageal carcinoma EC-1 cell line. Method: Inhibition of EC-1 cell proliferation at different concentrations of $As_20_3$ was assessed using the methyl thiazolyl blue colorimetric method (MTT method), with calculation of $IC_{50}$ value and choice of 20% of the $IC_{50}$ as the experimental drug concentration. Blank control, $As_20_3$, hyperthermia, radiotherapy group, $As_20_3$ + hyperthermia, $As_20_3$ + radiotherapy, hyperthermia + radiotherapy and $As_20_3$ + hyperthermia + radiotherapy groups were established, and the cell survival fraction (SF) was calculated from flat panel colony forming analysis, and fitted by the 'multitarget click mathematical model'. Flow cytometry (FCM) was used to detect changes in cell apoptosis and the cell cycle. Results: $As_20_3$ exerted inhibitory effects on proliferation of esophageal carcinoma EC-1 cells, with an $IC_{50}$ of 18.7 ${\mu}mol/L$. After joint therapy of $As_20_3$ + hyperthermia + radiotherapy, the results of FCM showed that cells could be arrested in the $G_2$/M phase, and as the ratio of cells in $G_0/G_1$ and S phases decreased, cell death became more pronounced. Conclusion: $As_20_3$ and hyperthermia exert radiosensitivity effects on esophageal carcinoma EC-1 cells, with synergy in combination. Mechanistically, $As_20_3$ and hyperthermia mainly influence the cell cycle distribution of EC-1 esophageal carcinoma cells, decreasing the repair of sublethal damage and inducing apoptosis, thereby enhancing the killing effects of radioactive rays.

Diversity, distribution, and antagonistic activities of rhizobacteria of Panax notoginseng

Ze-Yan Fan,Cui-Ping Miao,Xin-Guo Qiao,You-Kun Zheng,Hua-Hong Chen,You-Wei Chen,Li-Hua Xu,Li-Xing Zhao,Hui-Lin Guan 고려인삼학회 2016 Journal of Ginseng Research Vol.40 No.2

Background: Rhizobacteria play an important role in plant defense and could be promising sources of biocontrol agents. This study aimed to screen antagonistic bacteria and develop a biocontrol system for root rot complex of Panax notoginseng. Methods: Pure-culture methods were used to isolate bacteria from the rhizosphere soil of notoginseng plants. The identification of isolates was based on the analysis of 16S ribosomal RNA (rRNA) sequences. Results: A total of 279 bacteria were obtained from rhizosphere soils of healthy and root-rot notoginseng plants, and uncultivated soil. Among all the isolates, 88 showed antagonistic activity to at least one of three phytopathogenic fungi, Fusarium oxysporum, Fusarium solani, and Phoma herbarum mainly causing root rot disease of P. notoginseng. Based on the 16S rRNA sequencing, the antagonistic bacteria were characterized into four clusters, Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetesi. The genus Bacillus was the most frequently isolated, and Bacillus siamensis (Hs02), Bacillus atrophaeus (Hs09) showed strong antagonistic activity to the three pathogens. The distribution pattern differed in soil types, genera Achromobacter, Acidovorax, Brevibacterium, Brevundimonas, Flavimonas, and Streptomyces were only found in rhizosphere of healthy plants, while Delftia, Leclercia, Brevibacillus, Microbacterium, Pantoea, Rhizobium, and Stenotrophomonas only exist in soil of diseased plant, and Acinetobacter only exist in uncultivated soil. Conclusion: The results suggest that diverse bacteria exist in the P. notoginseng rhizosphere soil, with differences in community in the same field, and antagonistic isolates may be good potential biological control agent for the notoginseng root-rot diseases caused by F. oxysporum, Fusarium solani, and Panax herbarum.

Endophytic fungi harbored in Panax notoginseng: diversity and potential as biological control agents against host plant pathogens of root-rot disease

You-Kun Zheng,Cui-Ping Miao,Hua-Hong Chen,Fang-Fang Huang,Yu-Mei Xia,You-Wei Chen,Li-Xing Zhao 고려인삼학회 2017 Journal of Ginseng Research Vol.41 No.3

Background: Endophytic fungi play an important role in balancing the ecosystem and boosting host growth. In the present study, we investigated the endophytic fungal diversity of healthy Panax notoginseng and evaluated its potential antimicrobial activity against five major phytopathogens causing rootrot of P. notoginseng. Methods: A culture-dependent technique, combining morphological and molecular methods, was used to analyze endophytic fungal diversity. A double-layer agar technique was used to challenge the phytopathogens of P. notoginseng. Results: A total of 89 fungi were obtained from the roots, stems, leaves, and seeds of P. notoginseng, and 41 isolates representing different morphotypes were selected for taxonomic characterization. The fungal isolates belonged to Ascomycota (96.6%) and Zygomycota (3.4%). All isolates were classified to 23 genera and an unknown taxon belonging to Sordariomycetes. The number of isolates obtained from different tissues ranged from 12 to 42 for leaves and roots, respectively. The selected endophytic fungal isolates were challenged by the root-rot pathogens Alternaria panax, Fusarium oxysporum, Fusarium solani, Phoma herbarum, and Mycocentrospora acerina. Twenty-six of the 41 isolates (63.4%) exhibited activity against at least one of the pathogens tested. Conclusion: Our results suggested that P. notoginseng harbors diversified endophytic fungi that would provide a basis for the identification of new bioactive compounds, and for effective biocontrol of notoginseng root rot.

Diversity, distribution, and antagonistic activities of rhizobacteria of Panax notoginseng

Fan, Ze-Yan,Miao, Cui-Ping,Qiao, Xin-Guo,Zheng, You-Kun,Chen, Hua-Hong,Chen, You-Wei,Xu, Li-Hua,Zhao, Li-Xing,Guan, Hui-Lin The Korean Society of Ginseng 2016 Journal of Ginseng Research Vol.40 No.2

Background: Rhizobacteria play an important role in plant defense and could be promising sources of biocontrol agents. This study aimed to screen antagonistic bacteria and develop a biocontrol system for root rot complex of Panax notoginseng. Methods: Pure-culture methods were used to isolate bacteria from the rhizosphere soil of notoginseng plants. The identification of isolates was based on the analysis of 16S ribosomal RNA (rRNA) sequences. Results: A total of 279 bacteria were obtained from rhizosphere soils of healthy and root-rot notoginseng plants, and uncultivated soil. Among all the isolates, 88 showed antagonistic activity to at least one of three phytopathogenic fungi, Fusarium oxysporum, Fusarium solani, and Phoma herbarum mainly causing root rot disease of P. notoginseng. Based on the 16S rRNA sequencing, the antagonistic bacteria were characterized into four clusters, Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetesi. The genus Bacillus was the most frequently isolated, and Bacillus siamensis (Hs02), Bacillus atrophaeus (Hs09) showed strong antagonistic activity to the three pathogens. The distribution pattern differed in soil types, genera Achromobacter, Acidovorax, Brevibacterium, Brevundimonas, Flavimonas, and Streptomyces were only found in rhizosphere of healthy plants, while Delftia, Leclercia, Brevibacillus, Microbacterium, Pantoea, Rhizobium, and Stenotrophomonas only exist in soil of diseased plant, and Acinetobacter only exist in uncultivated soil. Conclusion: The results suggest that diverse bacteria exist in the P. notoginseng rhizosphere soil, with differences in community in the same field, and antagonistic isolates may be good potential biological control agent for the notoginseng root-rot diseases caused by F. oxysporum, Fusarium solani, and Panax herbarum.

Endophytic fungi harbored in Panax notoginseng: diversity and potential as biological control agents against host plant pathogens of root-rot disease

Zheng, You-Kun,Miao, Cui-Ping,Chen, Hua-Hong,Huang, Fang-Fang,Xia, Yu-Mei,Chen, You-Wei,Zhao, Li-Xing The Korean Society of Ginseng 2017 Journal of Ginseng Research Vol.41 No.3

Background: Endophytic fungi play an important role in balancing the ecosystem and boosting host growth. In the present study, we investigated the endophytic fungal diversity of healthy Panax notoginseng and evaluated its potential antimicrobial activity against five major phytopathogens causing root-rot of P. notoginseng. Methods: A culture-dependent technique, combining morphological and molecular methods, was used to analyze endophytic fungal diversity. A double-layer agar technique was used to challenge the phytopathogens of P. notoginseng. Results: A total of 89 fungi were obtained from the roots, stems, leaves, and seeds of P. notoginseng, and 41 isolates representing different morphotypes were selected for taxonomic characterization. The fungal isolates belonged to Ascomycota (96.6%) and Zygomycota (3.4%). All isolates were classified to 23 genera and an unknown taxon belonging to Sordariomycetes. The number of isolates obtained from different tissues ranged from 12 to 42 for leaves and roots, respectively. The selected endophytic fungal isolates were challenged by the root-rot pathogens Alternaria panax, Fusarium oxysporum, Fusarium solani, Phoma herbarum, and Mycocentrospora acerina. Twenty-six of the 41 isolates (63.4%) exhibited activity against at least one of the pathogens tested. Conclusion: Our results suggested that P. notoginseng harbors diversified endophytic fungi that would provide a basis for the identification of new bioactive compounds, and for effective biocontrol of notoginseng root rot.

Endophytic Trichoderma gamsii YIM PH30019: a promising biocontrol agent with hyperosmolar, mycoparasitism, and antagonistic activities of induced volatile organic compounds on root-rot pathogenic fungi of Panax notoginseng

Chen, Jin-Lian,Sun, Shi-Zhong,Miao, Cui-Ping,Wu, Kai,Chen, You-Wei,Xu, Li-Hua,Guan, Hui-Lin,Zhao, Li-Xing The Korean Society of Ginseng 2016 Journal of Ginseng Research Vol.40 No.4

Background: Biocontrol agents are regarded as promising and environmental friendly approaches as agrochemicals for phytodiseases that cause serious environmental and health problems. Trichoderma species have been widely used in suppression of soil-borne pathogens. In this study, an endophytic fungus, Trichoderma gamsii YIM PH30019, from healthy Panax notoginseng root was investigated for its biocontrol potential. Methods: In vitro detached healthy roots, and pot and field experiments were used to investigate the pathogenicity and biocontrol efficacy of T. gamsii YIM PH30019 to the host plant. The antagonistic mechanisms against test phytopathogens were analyzed using dual culture, scanning electron microscopy, and volatile organic compounds (VOCs). Tolerance to chemical fertilizers was also tested in a series of concentrations. Results: The results indicated that T. gamsii YIM PH30019 was nonpathogenic to the host, presented appreciable biocontrol efficacy, and could tolerate chemical fertilizer concentrations of up to 20%. T. gamsii YIM PH30019 displayed antagonistic activities against the pathogenic fungi of P. notoginseng via production of VOCs. On the basis of gas chromatography-mass spectrometry, VOCs were identified as dimethyl disulfide, dibenzofuran, methanethiol, ketones, etc., which are effective ingredients for antagonistic activity. T. gamsii YIM PH30019 was able to improve the seedlings' emergence and protect P. notoginseng plants from soil-borne disease in the continuous cropping field tests. Conclusion: The results suggest that the endophytic fungus T. gamsii YIM PH30019 may have a good potential as a biological control agent against notoginseng phytodiseases and can provide a clue to further illuminate the interactions between Trichoderma and phytopathogens.