Transformation Of Saponin Rb₁ From Ginseng Pathogen And Its Chemotaxis To Ginseng Root Exudates

Panax ginseng C.A.Mey.was Araliaceae perennial herb,ginseng main diseases seriously affected the ginseng production in our country,which seriously affects the development of ginseng industry.A variety of effective substances have been detected in the root exudates of ginseng,including 7 kinds of monomeric saponins Rb1,Rd,Rc,Rb3,Rf,Re and Rb2.The 13 amino acids are glutamic acid,lysine,serine,aspartic acid,arginine,threonine,alanine,cysteine,glycine,valine,isoleucine,phenylalanine and leucinea cid.There were 7 kinds of soluble sugars,such as galactose,fucose,mannose,glucose,arabinose,xylose and rhamnose.The results of previous experiments showed that Cylindrocarpon destructans,Alternaria panax,Rhizoctonia solani,Botrytis cinerea,Sclerotinia ginseng,and Fusarium solani showed a strong positive chemotaxis towards the low concentration of saponins,and the higher concentration of ginsenosides delayed the development of hyphae.Ginseng pathogen showed a growth of ginsenosides in a dose-dependent manner.For this reason,it was speculated that ginsenosides might act as chemoattractant or growth regulator,and the chemotaxis mechanism was also studied according to this idea.Previous research showed that saponin can be used as different pathogens of chemokines play certain factors in the process of pathogen infection in this study showed that the Fusarium solani and Alternaria panax maked ginsenoside Rb1 can be transformed,results show that saponin as a chemotactic factor play a role in the infection process,provide evidence for the study of chemotactic mechanism at the same time,the study of ginseng root exudates in other substances,such as carbohydrates,amino acids of different pathogenic fungi such as Fusarium solani,Alternaria Panax,Botrytis cinerea chemotaxis.The results of this study are as follows:1.The study on the transformation of ginsenoside Rb₁ by Fusarium solani was carried out.The optimum conditions were as follows:substrate time 24h;substrate concentration 0.25mg/mL;culture medium pH=5;culture time 9 days;culture temperature 28℃.The highest conversion rate reached 56%.The process of transformation was ginsenoside Rb1-Rd-F2-CK.2.The transformation of ginsenoside Rb₁ by Alternaria panax showed that the best conditions for transformation were determined by experiments.The best conditions for the transformation of Rb₁ were:substrate addition time 12h;substrate concentration 0.2 mg/mL;medium pH=6;culture time 7 days;culture temperature 28℃.The highest conversion rate of88%.And it was clarified that the experimental conversion pathway was ginsenoside Rb₁-Rd-F₂.3.The Fusarium solani had obvious chemotactic effect on lysine,serine and fucose.The chemotactic migration index were 1.1777,.2122,and 1.2583 respectively.The chemotactic growth rates were 0.3595,0.3797,and 0.3893 respectively.The spore germination rates were62.66%,68.00%,59.33%respectively.The dry weight of mycelia were 369.06,404.87,414.77mg/L.Ginseng root rot spores germination rate,mycelial dry weight increased significantly.4.The Alternaria panax showed a strong chemotactic effect on arginine,glutamic acid,aspartic acid and threonine,with the chemotaxis rates of 1.24,1.38,1.31 and 1.27,respectively.The growth rates were 0.5346,0.4650,0.4360,and 0.5173.The spore germination rates were57.33%,63.00%,58.00%and 56.67%.The dry weight of mycelia were 372.9,388.5,390.2 and335.4 mg/L,respectively.Amino acids as chemotactic substances showed efficient chemotactic effect,and some even appeared in the high concentration of inhibition phenomenon.5.The Botrytis cinerea showed a positive trend towards different concentrations of alanine,aspartic acid and rhamnose at medium and low concentrations,with CMI of 1.2594,1.2209 and1.1812,spore germination rates were:61.00%,57.00%,and 55.00%.Mycelium growth rate were:0.4127,0.3921,0.3885.Mycelium dry weight were:431.8,311.8,256.9mg/L,of which215.3 mg/L in the control group.