| Cherry Tomato(Solanum.lycopersicum var.cerasiforme)is one of the important crops in China.Cherry tomato is easy to be damaged by pathogenic microorganisms.Fusarium verticillioides,belonging to the genus Fusarium,is widely distributed all over the world.It is a fungus that causes many kinds of plant diseases.It can cause postharvest cherry tomato fruit rot after infection.The S3-1(Bacillus velezensis)was isolated from the soil of Cucumber in the early stage of this experiment.It had good inhibitory effect on Botrytis cinerea,Gibberella graminearum and Rhizoctonia solani.In this study,S3-1 was applied to control the postharvest rot of cherry tomato and keep the fruits fresh.The results are as follows:(1)S3-1 grew well in the environment of 25-35℃and p H 6.5.Considering that the surface of cherry tomato is medium acid and the fruit matured in summer and autumn,S3-1 can be applied in it.(2)The results of plate confrontation test of S3-1 fermentation broth,bacterial suspension,supernatant and volatiles with fungi were analyzed.It was found that the inhibition rate of fermentation broth reached 63.75%after 24 hours of culture,48.7%of the supernatant with 100%concentration after 72 hours of culture,56.54%of the bacterial suspension with 1×10~8CFU/ml after 24 hours of culture,The volatiles obtained by 24-hour culture and coated with 1×10~6 CFU/ml fermentation broth had good and long-term inhibitory effect on the growth of fungal colonies.(3)It was found that S3-1 could affect the morphology of fungal spores and hyphae when they were co-cultured with fungi and S3-1 could prevent their germination and growth;the electrical conductivity of S3-1 supernatant and fungal spore suspension increased when they were co-cultured.It was speculated that there were some substances in the supernatant that destroyed the fungal cell wall and increased the cell permeability;S3-1 volatiles could cause the morphology of fungal hyphae to appear white and aging,and the results of GC-MS analysis showed that the volatiles contained a variety of antioxidative phenols and unsaturated fatty acids,which also inhibited the growth of fungi.(4)The effect of S3-1 on cherry tomato was analyzed.The incidence rate of eighth days after inoculation with fungi and inoculating fermented liquid was 70%,which was16.05%lower than that of control group.The total area of the disease spots was 10.62cm~2,which was 48.62%lower than that of the control group.The fruits inoculated with fermentation broth and then fungi had no disease in the first 4 days,and the incidence rate was 36.67%on the eighth day.The control group decreased 63.33%and the total area of the disease spot was 3.19 cm~2,93.85%less than that of the control group,indicating that early inoculation of each component of S3-1 can effectively inhibit the occurrence and spread of cherry tomato fruit rot caused by Fusarium verticillioides.(5)The effect of S3-1 volatiles on cherry tomato fruit rot disease was analyzed,on the eighth day,the incidence rate was 79.17%,the control was 14.17%higher,the total lesion area was 17.84 cm~2,the control was 58.95%higher.The results showed that volatiles could slow down the development of fruit rot.(6)It was found that S3-1 could increase the contents of POD,PPO,MDA and flavonoid,the content of MDA in response to plant injury decreased,the expression of NPR1 gene was up-regulated.Through literature review,S3-1 genome mining,metabolite prediction and analysis of previous experimental results,it was found that S3-1 could produce surfactant which could cause NPR1 gene up-regulation,and S3-1had good colonization in Cherry Tomato wound,which confirmed the colonization of S3-1 and its activity in the wound of fruit epidermis are one of the reasons to help fruit resist fungal invasion and stimulate plant resistance to some extent.(7)In Cherry Tomato preservation experiment,the fruits treated with S3-1fermentation liquor had fresh color,full appearance,less peel permeability,less mass loss,incidence rate and disease severity during the 49 day storage period.Cherry Tomato’s nutrient substances were higher than control,and the loss of them was less.After apply S3-1 to the cherry tomato,the fruit was better and fresher. |
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