| Pseudostellaria heterophylla has a variety of medicinal effects.Guizhou has a history of cultivating P.heterophylla nearly 30 years,and has become the main producing area of it.Due to the increasing of planting area,continuous cropping and poor field management,the root rot of P.heterophylla has become more serious and hinders the development of P.heterophylla industry.In order to better defense and control this disease,based on the previous studies,SBG9 strain with better control effect in the field was selected for identification in this study.To test its antibacterial effect on some pathogens of P.heterophylla;To optimize the bottled fermentation conditions;To explore the effect on the sporulation and hyphae of Fusarium oxysporum of P.heterophylla;In addition,the influence of SBG9 strain and its fermentation broth on the root rot was explored through transcriptome sequencing analysis technology,in order to provide certain theoretical basis for the prevention and control of the root rot.The mian results were as the follows.(1)SBG9 was identified as Bacillus velezensis by colonial morphology,physiological,biochemical and molecular systematics;(2)The inhibitory rate of SBG9 strain against F.oxysporum was 76.13%,against Sclerotium rolfsii was 67.75%,and against Alternaria tenuissima was 62.21%;(3)The orthogonal test results show that the optimized antibacterial rate increased by 25.62%,with LB as the starting medium,inoculation amount of 1%,fermentation time of 72 h,and culture temperature of 30?;Adding aseptic fermentation broth 1 m L to the medium with a suitable concentration of 10 m L for the medium plate—the fermentation broth to the medium is 1:10(volume ratio V/V).(4)The sporulation amount of pathogen in CK group had a little change in the first 6 days,but increased after 7 days;The sporulation amount of treatment group after 6 and 7 days was lower than the CK,and the mycelia and spores of the treatment group became enlarged and deformed in the stress of biocontrol fungus;The potted control effect of SBG9 strain against root rot of P.heterophylla was 67.6%.(5)The transcriptome sampling time was determined by the growth and sporulation of the pathogen after biocontrol bacteria stress.F.oxysporum co-cultured with biocontrol strain SBG9(S)and fermentation broth(F)was sampled at 3,5 and 7 days,respectively.Sequencing data of 27 samples were all valid data after filtered analysis.GO analysis found that the comparison group: CK-3d-VS-F-3 d differentially expressed genes(DEGs)were up-regulated by 666 and down-regulated by 850;CK-3 d-vs-S-3 d DEGs were up-regulated by 346 and down-regulated by 269;CK-5 d-vs-F-5 d DEGs were up-regulated by 678 and down-regulated by 739;CK-5 d-vs-S-5 d DEGs were up-regulated by 432 and down-regulated by 382;CK-7 d-vs-F-7 d DEGs were up-regulated by 690 and down-regulated by 776;CK-7 d-vs-S-7 d DEGs were up-regulated by 1128 and down by 275.(6)The results of KEGG enrichment can be obtained as follows: The 1516 DEGs of the comparison group CK-3 d-vs-F-3 d were enriched in 83 metabolic pathways;615 DEGs of CK-3 d-vs-S-3 d were enriched in 58 metabolic pathways;1417 DEGs of CK-5 d-vs-F-5 d were enriched in 85 metabolic pathways;814 DEGs of CK-5 d-vs-S-5 d were enriched in 63 metabolic pathways;The 1466 DEGs of CK-7 d-vs-F-7 d were enriched in 93 metabolic pathways;The 2403 DEGs of CK-7d-vs-S-7 d were enriched in 108 metabolic pathways;(7)A total of 18 components were isolated and purified from the aseptic fermentation broth,and Surfactin was preliminarily speculated to exist in the isolated aseptic fermentation broth. |
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