Study On The Regulation And Mechanism Ofdecline Of Resist Ance To Gray Mold In Tomato

Fruit disease resistance is the most concerned problem during postharvest storage period,which seriously affects the postharvest rot rate of fruits and vegetables.Fruit decay not only restricts the economic benefits of fruit and vegetable industry,but also affects a series of problems such as consumer experience and consumption.At present,people’s understanding of post-harvest storage of fruits and vegetables mainly focuses on the increased susceptibility of fruits to pathogens after ripening,and the mechanism of disease resistance and decline after fruit picking is still not well understood.There are still many difficult questions about the deep mechanism and regulation mode of the change of fruit and vegetable disease resistance after cutting.To clarify these change rules and mechanisms will have a great impact on reducing the rot after cutting,innovating the storage and fresh-keeping technology after cutting,improving the storage period and commercial economic benefits of fruit and vegetable.In this study,tomato fruit（Solanum lycopersicum）was used as experimental materials,and transcriptome（RNA-seq）and multiple response monitoring（SRM/MRM）methods were used to analyze the differential gene expression before and after color turning stage of tomato fruit,as well as the metabolic rules of 8 kinds of plant hormones,their homolog and metabolic precursors.The mechanism of tomato fruit disease resistance and decline was studied from the aspects of plant hormones,transcription factors and epigenetics by means of postharvest pathology and molecular biology.The function of the gene was verified based on reverse genetic transformation experiment to explore the resistance of bHLH47 to tomato fruit.The main results are as follows:（1）Transcriptome analysis of tomato（green ripe fruit,red ripe fruit）before and after color turning stage.The transcriptome libraries of green ripening tomato（MGW）and red ripening tomato（RRW）were constructed and sequenced.12245 differentially expressed genes were identified in MGW and RRW samples.There were 5763 up-regulated and 6482 down-regulated genes in MGW and RRW.During tomato fruit ripening,differentially expressed genes mainly respond to plant hormone signal transduction and plant-pathogen interaction.（2）Effects of hormones on postharvest gray mold capacity of tomato fruits.Determination of 15 plant hormones in MGH and RRH tomato during ripening by liquid chromatography-mass spectrometry.JA and JA-ILe decreased from 30.72 ng/g and 2.76ng/g in green ripening stage（MGH）to 2.33 ng/g and 0.069 ng/g in red ripening stage（RRH）.（3）Analysis on the rule and mechanism of postharst resistance to gray mold decline of tomato fruits.The mechanism of the decline of botrytis cinerea was studied from transcription factors and epigenetics.The expression of jasmonic acid synthesis genes OPR3 and AOS were up-regulated after the expression of bHLH47 was silenced by p TRV2-bHLH47 vector,and bHLH47 inhibited jasmonic acid synthesis genes.5-Azacytidine as demethylation reagent,can speed up green ripe（MG）tomato fruit ripening,from the green ripening phase of the application of distilled water and 5-Azacytidine disease spot size and incidence confirms this;On the contrary,the size and incidence of disease spots in red ripening fruits decreased significantly.（4）Optimization of virus-induced gene silenceing in Ailsa Craig tomato fruit.In this paper,two infection methods,inoculation concentration and inoculation time of agrobacterium were optimized from sterile syringe and bamboo stick.Agrobacterium was inoculated with sterile syringe about 35 days after flowering of tomato fruit.The concentration of inoculated bacteria was OD₆₀₀1.8,and the silencing effect was better.