| Rusty root rot disease is one of the commonest and serious root diseases during Asian ginseng(Panax ginseng)cultivation.It is so difficult to control that it significantly reduces the quality and limits the production of ginseng in China.The pathogen of this disease identified as Cylindrocarpon destructans in previous studies.With the founding of the teleomorph and complex of C.destructans,the fungal species causing rusty root rot disease of Panax ginseng in China maybe have changed.Biological control is a vital way to control this disease.In the biocontrol system of rusty root rot disease of P.ginseng,the biocontrol mechanism of biocontrol microorganisms is the focus of research,but there were few studies about how the pathogen responses to biocontrol strains.Determining pathogen species causing rusty root rot disease of P.ginseng under the new taxonomy system and exploring the molecular mechanism how the pathogen response to biocontrol bacterial stress will provide the basis for the etiology of ginseng rusty root rot disease and understanding of the interaction of biocontrol strain and pathogen and control this disease.Therefore,this study identified the pathogenic species causing ginseng rusty root rot disease by morphology and muti-genes analysis and analyze the regulatory mode of Ilyonectria robusta infecting ginseng under biocontrol bacteria.The main results and conclusions are shown as follows:Five fungal species causing rusty root rot disease of P.ginseng in China were I.robusta,I.mors-panacis,I.communis,I.pseudodestructans,and Dactylonectria pauciseptata.159 Cylindrocarpon-like isolates were obtained from diseased samples collected from 18 counties,8 cites in Jilin and Heilongjiang provinces,China.Four Ilyonectria species were C.destructans/I.radicicola complex but D.pauciseptata.Among them,I.robusta had the highest isolation frequency and was distributed in various regions,which indicated I.robusta was the main specie.I.pseudodestructans and D.pauciseptata were firstly reported on the P.ginseng.154 isolates including five species were pathogenic to P.ginseng.I.pseudodestructans could lead to root rot.D.pauciseptata only could lead to surficial discoloration but root rot.I.robusta,I.mors-panacis,and I.communis could cause root rot and discoloration of ginseng root.The transcriptomic regular mechanism of I.robusta infecting ginseng under the treatment of biocontrol bacteria was the complex network involved in multiple genes and pathways.Biocontrol strain NJ13(Bacillus methyltrophicus)could inhibit mycelium of I.robusta and slowed down the development of I.robusta infecting ginseng.The transcriptomic data discovered 3729 novel genes and annotated some functions of 2804 genes,which enriched the gene resource of I.robusta.I.robusta had 1681 significantly differentially expressed genes including 1140 genes up-regulated and 541 genes down-regulated under the treatment of NJ13.I.robusta up-regulated the expression of genes related to oxidoreductase activity,peroxisome,carbohydrate metabolism process,glycolysis genes,glycerolipid metabolism,fatty acid degradation pathway,response to stress,and biosynthesis of antibiotics.The expression of genes about ribosome biogenesis,r RNA process was down-regulated.These results indicated that under the treatment of biocontrol strain NJ13,I.robusta controlled itself to infect ginseng through up-regulation of genes related to antioxidant,energy metabolism,response to stress,and cell membrane,and down-regulation of genes about ribosomal synthesis. |
