| Ginseng(Panax ginseng C. A. Mey) is Araliaceae medicinal plants,it is a traditional and valuable Chinese herbal medicines, mainly distributed in China Chang bai Mountain area.Ginseng rust rot(Cylindrocarpon destructans) is one of the more serious and universal soil-borne diseases. The objective of this study is biocontrol ginseng rust rot, on the basic of obtain a Bacillus methylotrophilus NJ13 which to ginseng rust rot has bacteriostatic effect,that to carry out biocontrol function. The results are as follows:1.The use of the growth rate method, hyphae growth assay, spore germination method, indoor inoculation method and field efficacy test to measure the NJ13 bio-control effect of ginseng rust rot. When NJ13 cell concentration 107 cfu / m L, Cylindrocarpon destructans hyphae growth inhibition rate of up to 100%, the spore germination inhibition rate of 97.37%, the concentration of 105 cfu / m L, completely inhibited Cylindrocarpon destructans produce spores;NJ13 fermentation liquid which for Cylindrocarpon destructans mycelial growth inhibition rate was 85.1%, and spore germination rate was 92.11%, sporulation inhibition rate was 84.75%;Indoor bacteriostatic inoculate observed health ginseng inoculated Cylindrocarpon destructans that disease spot color deepened and decay after 8d, and after NJ13 bacterial fermentation and processing,then inoculated Cylindrocarpon destructans the ginseng no symptom after inoculation 8d. In the field of prevention of ginseng seedling and adult rust rot test results show that the 108 cfu / m LNJ13 strains of bacterial suspension after treatment, ginseng seedling rot rust incidence rate of 13.55%, field control effect was 73.63% for adult ginseng rust rot field efficacy reached 70.40%.2.By the study of NJ13 microscopic morphology, induced ginseng defense gene expression changes, and ginseng rhizosphere bacterial communities Change of high-throughput sequencing analysis and so on. revealed the biocontrol bacteria NJ13 on ginseng rust rot biocontrol effect.Microscopic morphology observed, Bacillus methylotrophilus NJ13 for Cylindrocarpon destructans mycelium growth had a significant inhibitory effect,which was inhibited mycelium deformity, swelling and partial dissolution phenomena; fluorescence quantitative PCR detected,after NJ13 induced ginseng PAL, β-1,3-glucanase and chitinase 3 kinds of defense genes, it were improved to varying degrees different time points after inoculate than the expression of a sterile water control, and the peak laws to converge, there were induced in 3 d and 30 d after induction,which induced the first 3d, β-1,3-glucanase gene expression was increased by the largest amount representing up to 32 times. Community diversity of different treatments exist in the sample bacteria differences, NJ13 which is treated ginseng rhizosphere soil bacterial community diversity is the highest, followed by B40> C40> B21> C21> C7> B7, and over time, its diversity is also increasing; the genus level species richness heat map shows that the bacterial community among treatments abundance of different genera in the event of change;diversity dissimilarity coefficient and UPGMA cluster analysis found that after NJ13 strain treatment 7d and 21 d with the water control treatment the same point in time ginseng rhizosphere soil microbial diversity dissimilarity coefficient significantly different, dissimilarity coefficients were higher than 0.3, the highest dissimilarity coefficient B7 and C21, reaching0.357, and to deal with after 40 d when the control dissimilarity coefficient dropped to 0.20 to0.278, bacterial community structure tend to stable. Through this study clearly Bacillus methylotrophilus NJ13 prevention effect and mechanism of biocontrol to ginseng rot rust, to lay the foundation for the potential of the biocontrol, development of biocontrol products, more effectively prevent the occurrence of ginseng rust rot. |
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