| Bacillus subtilis is a biocontrol bacteria with strong antibacterial activity,broad-spectrum of inhibition,safe and non-toxic.Litchi anthracnose and Peach brown rot,caused by Colletotrichum gloeosporioides and Monilinia fruticola,is the major cause of litchi and peach postharvest losses.In this paper,Bacillus subtilis CF-3 was selected as the target bacteria,and Colletotrichum gloeosporioides and Monilinia fruticola were selected as tested fungal pathogens.The inhibitory effects of volatile organic compounds(VOCs)produced by Bacillus subtilis CF-3 on postharvest pathogenic fungi were analyzed and compared by proteomics and transcriptomics.Revealing the molecular mechanism of CF-3 VOCs inhibiting two post-harvest pathogenic fungi from gene and protein levels.Effect of VOCs combined heat treatment on postharvest diseases of peach and litchi fruits by detecting physiological and biochemical indicators of fruits.This study can provide a valuable foundation for the analysis of VOCs produced by biocontrol bacteria.The major results were as follows:1)The effects of CF-3 VOCs and its active ingredient 2,4-di-tert-butylphenol on C.gloeosporioides were analyzed by high-throughput sequencing.The transcriptome datas are as follows: the total number of differentially expressed genes(DEGs)in the LC vs LK group was 2320,the total number of DEGs in the L24 vs LK group was 2918.It is speculated that VOCs and 2,4-di-tert-butylphenol treatment may have great similarities in some respects.The DEGs were enriched in the biological process,molecular function,and cellular component.The related pathways involved in DEGs were analyzed by KEGG pathway enrichment,which was mainly enriched in the biosynthesis pathway of amino acids and carbon metabolism pathway.The DEGs in LC vs LK group were mainly enriched in the phenylalanine metabolism pathway and alanine pathway,the DEGs in L24 vs LK group were mainly enriched in the amino sugar and nucleotide sugar metabolism pathway,fatty acid biosynthesis pathway.2)The effects of CF-3 VOCs and its active ingredient 2,4-di-tert-butylphenol on C.gloeosporioides were analyzed by TMT quantitative project.The proteome datas are as follows: the total number of differentially expressed proteins(DEPs)in the LC vs LKgroup was 565,the total number of DEPs in the L24 vs LK group was 831.The relevant metabolic pathways involved in DEPs were analyzed by KEGG pathway annotation.The results showed that the DEPs were mainly enriched in the energy metabolism pathway of C.gloeosporioides,lipid metabolism pathway,biosynthesis pathway of secondary metabolites(LC vs LK)and amino acid metabolism pathway(LC vs LK).Other pathways,including translation pathway,signal transduction pathway,transport and catabolism pathway,have significant effects.The results showed that CF-3 VOCs and2,4-di-tert-butylphenol may inhibit the growth of C.gloeosporioides by affecting the basic substance metabolism and energy metabolism related proteins of C.gloeosporioides.3)The effects of CF-3 VOCs on M.fruticola were analyzed by high-throughput sequencing.The transcriptome datas are as follows: the total number of differentially expressed genes(DEGs)in the TK vs TC group was 1602.The DEGs of pathway were enriched and analyzed.The results showed that the DEGs were mainly enriched in the biosynthesis pathway of antibiotics,starch and sucrose metabolism pathway,and biosynthesis pathway of amino acids.Carbohydrate transport and metabolism and energy production and conversion were significant classifications.The results showed that CF-3VOCs may inhibit the growth of M.fruticola by affecting the carbohydrate and energy metabolism related pathways of M.fruticola.4)The effects of CF-3 VOCs on M.fruticola were analyzed by TMT quantitative project.The proteome datas are as follows: the total number of differentially expressed proteins(DEPs)in the TK vs TC group was 1008.The DEGs were enriched in the biological process,molecular function,and cellular component.The DEPs of pathway were enriched and analyzed.The results showed that the DEPs were mainly enriched in the biosynthesis pathway of secondary metabolites,carbon metabolism pathway,and biosynthesis pathway of antibiotics.5)The effects of combined treatment on two pathogenic fungi on litchi and peach fruit were studied by VOCs combined heat treatment techniques.After combined treatment,the decay index can be significantly reduced,the weight loss rate,and soluble solid content of peach fruits and litchi fruits,hardness and maturity of peach fruits can be better maintained.Furthermore,the activities of POD,PPO,CAT,and SOD significantlyincreased compared to control and single treatment group,and the activities of PAL,CHI,and ?-1,3-GLU significantly increased compared to control and single treatment group.These results indicated that VOCs combined heat treatment can complement each other,activate antioxidase to scavenge redundant reactive oxygen to protect plant cells and disease resistance enzyme to defense the infection of fungal pathogens. |
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