Cui-Ping Miao

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

Background Rhizospheric fungi play an essential role in the plant–soil 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 sequences was 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.

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

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.

A new sesquiterpenoid from Ligusticum chuanxiong Hort

A new sesquiterpenoid named (-)-alloaromadendrane-4β,10α,13,15-tetrol was isolated from the rhizome of Ligusticum chuanxiong Hort., together with two known compounds, campest-4-en-3-one and 3-carboxyethyl-phthalide. Their structures were elucidated on the basis of spectroscopic and chemical analysis. All the compounds showed mild antimicrobial activity.

Sesquiterpenoids from the endophytic fungus Trichoderma sp. PR-35 of Paeonia delavayi.

A new bisabolane‐type sesquiterpene, trichoderic acid (1), and a new acorane‐type sesquiterpene, 2β‐hydroxytrichoacorenol (2), along with three known compounds, cyclonerodiol (3), cyclonerodiol oxide (4), and sorbicillin (5), were isolated from the culture broth of Trichoderma sp. PR‐35, an endophytic fungus isolated from Paeonia delavayi. Their structures were elucidated on the basis of their IR, MS, and 1D‐ and 2D‐NMR analyses. The antibacterial and antifungal activities of 1–5 towards various types of bacteria and fungi were tested. Most of the compounds showed moderate or weak antimicrobial activities in an agar‐diffusion assay.

Diversity, distribution and biotechnological potential of endophytic fungi

Endophytic fungi, living in the inner tissues of living plants, have attracted increasing attention among ecologists, taxonomists, chemists and agronomists. They are ubiquitously associated with almost all plants studied to date. Numerous studies have indicated that these fungi have an impressive array of biotechnological potential, such as enzyme production, biocontrol agents, plant-growth promoting agents, bioremediation, biodegradation, biotransformation, biosynthesis and nutrient cycling. These fungi may represent an underexplored reservoir of novel biological resources for exploitation in the pharmaceutical, industry and agriculture. This review focuses on new findings in isolation methods, biodiversity, ecological distribution and biotechnological potential.

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

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.

Salt tolerance of endophytic Trichoderma koningiopsis YIM PH30002 and its volatile organic compounds (VOCs) allelopathic activity against phytopathogens associated with Panax notoginseng

Trichoderma spp. are widely used in the biological control of plant pathogens due to their high antagonistic and mycoparasitic potential. However, interaction among phytopathogens–Trichoderma–plant–soil is very complex and needs further investigation. In this study, we report the high salt-tolerant and mycoparasitic properties of endophytic T. koningiopsis YIM PH30002, isolated from the root of 2-year-old healthy Sanqi (Panax notoginseng), and its allelopathic antagonistic activity against phytopathogens associated with the host plant. Trichoderma koningiopsis YIM PH30002 exhibited significant inhibition of the growth of four host root-rot phytopathogens, Phoma herbarum, Fusarium flocciferum, Scytalidium lignicola, and Epicoccum nigrum, by covering the colony of phytopathogens, coiling and twisting the mycelium in a probable mechanism of mycoparasitism, producing volatile organic compounds (VOCs). In potato dextrose broth (PDB) culture medium, T. koningiopsis YIM PH30002 produced at least ten kinds of volatile substances which were identified as alkanes, monoterpenes and arenes, heterocycles, and aldehydes by GC-MS. The results indicate that YIM PH30002 can exert antagonistic actions by integrated ways to help its host defend diseases, and could be used as a promising candidate for the biological control of P. notoginseng root-rot disease.

Secondary metabolites of endophytic fungus Xylaria sp. YC-10 of Azadirachta indica

0009-3130/11/4705-0858 2011 Springer Science+Business Media, Inc. Yunnan Institute of Microbiology, Yunnan University, Kunming 650091, P. R. China, e-mail: shwu123@126.com. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 749–751, September–October, 2011. Original article submitted June 10, 2010. Chemistry of Natural Compounds, Vol. 47, No. 5, November, 2011 [Russian original No. 5, September–October, 2011]

Koninginins N-Q, Polyketides from the Endophytic Fungus Trichoderma koningiopsis Harbored in Panax notoginseng.

Four new fungal polyketides named koninginins N-Q (1–4), together with four known analogues (5–8), were isolated from the endophytic fungus Trichoderma koningiopsis YIM PH30002 harbored in Panax notoginseng. Their structures were determined on the basis of spectral data interpretation. These compounds were evaluated for their antifungal activity, nitric oxide inhibition, and anticoagulant activity.Graphical Abstract

Koninginins R-S from the endophytic fungus Trichoderma koningiopsis

Abstract Two new metabolites named koninginins R-S (1–2) were isolated from the culture of Trichoderma koningiopsis YIM PH30002. Their chemical structures were elucidated by the extensive spectroscopic analysis. These isolated compounds showed certain antifungal activities against phytopathogens, Fusarium flocciferum and Fusarium oxysporum.