| Panax notoginseng,Sanqi in Chinese,is a perennial herbal plant belonging to Araliaceae,its dried roots and rhizomes have the medicinal values of dispersing blood stasis,stopping bleeding,relieving swelling and pain.Nowadays,there is a great increasing in the demand of P.notoginseng original material on medicine,health care and cosmetics field.However,the serious continuous cropping obstacle problem has not been resolved,and root rot is one of the most common causes.There are some drawbacks in conventional chemical agent,such as the large dosage,the poor effect and the most serious damage is pesticide residue,which is harmful to the quality and safety of medicine.Therefore,screening high efficiency,low toxicity and no residue botanical fungicides as botanical pesticides can provide reference for the control of P.notoginseng root rot diseases.Mycelial growth rate was used to determine the inhibitory activity of volatiles and aqueous extracts of fennel(Foeniculum vulgare Mill.),rape(Brassica campestris L.),crown daisy(Chrysanthemum coronarium L.)and bitter mustard(Brassica integrifolia)on three P.notoginseng root rot pathogens,(Fusarium solani)F-3,(Phytophthora cactorum)D-1,and(Cylindrocarpon destructans)RS006.The results were as follows.The volatiles of crown daisy had the strongest inhibitory effect on F-3 and RS006,the inhibitory rates were 19.16%and 50.84%,respectively;the volatiles of bitter mustard had the strongest inhibitory effect on D-1,the inhibitory rate was 52.72%;the strongest plant to RS006 was crown daisy,the inhibitory rate was 50.84%;the order of the comprehensive antifungal activity on three pathogens was crown daisy,bitter mustard,fennel and rape,the inhibitory rates were 20%-35%,and the difference of the four plants were significant except bitter mustard and fennel.Study on the antifungal activity of aqueous extracts,rape had the strongest inhibitory effect on F-3 and D-1,the inhibitory rates were 37.72%and 89.00%,respectively;crown daisy had the strongest inhibitory effect on RS006,and the inhibitory rate was 12.62%;the order of the comprehensive antifungal activity to three pathogens was rape,bitter mustard,fennel and crown daisy,the inhibitory rate was 30%-45%,the difference of the four plants were significant.The inhibitory effect gradually increased with the increase of concentration of volatiles and aqueous extracts.Gas chromatography-mass spectrometer(GC-MS)were used to analyze the monomer components of four plant volatiles and aqueous extracts.The results showed that there were great differences in volatiles between the four plants in the two treatments of cutting and grinding.The main volatile species of cutting fennel were Alkenes and Terpene,the relatively high content monomer components were 1,6-dimethyl-1,5-Cyclooctadiene and Estragole;the main volatile species of grinding fennel were Acids and Alcohols,the relatively high content monomer components were α-hydroxy-3-methoxy-Benzeneacetic acid and 1-(4-Methoxyphenyl)propane-1,2-diol.The main volatile species of cutting rape were Sulfur ether and Alkane,the relatively high content monomer component were dimethyl disulfide;the main volatile species of grinding rape were Alcohols,the relatively high content monomer component were(Z)-3-Hexen-1-ol and(E)-3-Hexen-1-ol.The main volatile species of cutting crown daisy were Terpene and Alkene,the relatively high content monomer component were(3-Myrcene,(Z)-3,7-dimethyl-1,3,6-Octatriene.and β-Ocimene;the main volatile species of grinding crown daisy were Terpene and Alcohols,the relatively high content monomer component were β-Myrcene and Linalool.The main volatile species of cutting bitter mustard were Carboxylic ester and Sulfur ether,the relatively high content monomer component were 3-Hexen-1-ol acetate and dimethyl disulfide;the main volatile species of grinding bitter mustard were Isothiocyanate and Alcohols,the relatively high content monomer component were Allyl isothiocyanate and(Z)-3-Hexen-1-ol.Most of the substances found in the aqueous extracts of four plants’ stems and leaves were similar,the main species were Acids,Alcohols,Glucide;but there is a slight difference in the relatively high content of the monomer.The relatively high content monomer components of fennel stem were Glucose and Uracil;in the leaves were 2-Hydroxyisocaproic acid and o-Methoxymandelic acid.The relatively high content monomer components of rape stem were Glucose and Psicose;in the leaves were Uracil and Ferulic acid.The relatively high content monomer components of crown daisy stem were Psicose and Glucose;in the leaves were Azelaic acid and Uracil.The relatively high content monomer components of bitter mustard stem were Butanedioic acid and Mannose;in the leaves were Adenosine and Uridine.Overall,the stems of four plants contain more carbohydrates than leaves,while leaves contain more acids than stems.16 volatile monomers and 2 positive controls were selected to test the antifungal activity in further experiments.By calculating the Virulence regression equation and ECso,10 monomer volatiles were screened out finally.The sequence of comprehensive antifungal activity were:Allyl Isothiocyanate>Isobutyl sothiocyanate>Dimethyl trisulfide>Linalool>Bis(methylthio)methane>Methyl allyl disulfide>Estragole>(Z)-3-Hexen-1-ol>Dimethyl Disulfide>Anisic aldehyde.In result,rape and bitter mustard,which belong to brassica plant,has stronger antifungal activity against P.notoginseng root rot pathogens,brassica plants can be used as the main source to screen botanical fungicide.Isothiocyanate and sulfur ether were more suitable for the preparation of plant-derived fungicides.In this study,4 common vegetables in Yunnan were used as raw materials to test the antifungal activity of plant tissues and volatile monomers on Panax notoginseng root rot pathogens,and 10 monomers with strong antifungal activity were screened out.The results will provide materials for the preparation of botanical fungicide,and it is important for preventing and controlling Panax notoginseng root rot and relieving the continuous cropping obstacle. |
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