Effect And Mechanism Of Cyflumetofen On Apple Quality

As an effective technical means to reduce diseases,insects,grass and other harmful organisms,pesticides can increase production and income of agricultural products.Meanwhile,pesticides could cause quality safety issues and environmental pollution due to excessive or unreasonable use,and even affect the quality of agricultural products,leading to changes in their nutrient component,aroma,taste,color and texture,etc.The pesticide cyflumetofen is a novel acaricide with special mechanism that is applied on citrus and apples for red spider mite control.There is a good applying foreground for cyflumetofen.The research object of our study is cyflumetofen,and the research medium is apple.Modern detection and analysis technologies and omics technology were used to study the effects of cyflumetofen on apple quality.The purpose of our study is to provide a reasonable basis for the scientific use of cyflumetofen and a theoretical reference for improving the quality of apples.The main results are as follows:1.Using the electronic nose technique to analyze flavor differences,it was found that the overall flavors of apple samples treated with different concentrations of cyflumetofen were significantly different.And the difference between the five-fold dosage group and the control group was the largest.After that,the main flavor compounds of apple samples were analyzed qualitatively and quantitatively by using Gas Chromatography-Ion Mobility Spectroscopy(GC-IMS)and Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry(SPME-GC-MS)techniques.Results showed that the compositions and contents of volatile flavor substances of apple samples treated with cyflumetofen were obviously different.The contents of esters and alcohols in apple decreased with the increase of application concentration of cyflumetofen.While the total amount of hydrocarbons increased slightly,and the contents of substances such as aldehydes and ketones did not change significantly.2.A variety of detection methods were used to quantify the typical nutritional indexes of apples in order to evaluate the effects of different concentrations of cyflumetofen on apple nutrients.The results showed that the application of cyflumetofen had no significant effects on the contents of total sugar,soluble solids,total phenol and Ca element in apples,but decreased the contents of glucose,total protein,K and Mg.The contents of fructose,malic acid,lactic acid and VE increased,as well as the contents of sorbitol and VC decreased at 1.5-fold dosage group,while these trends were weakened at 5-fold dosage group.In addition,the contents of most amino acids after application of cyflumetofen have changed to some extent.Amino acids,as synthetic precursors of aroma substances,the change of which may involve complex mechanism effects.3.The non-target metabolomics of cyflumetofen-treated apples was investigated using ultra-high performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS)combined with Orthogonal Partial Least Squares-Discriminant Analysis(OPLS-DA)and KEGG metabolic pathway analysis.The results showed that there were 39 differential metabolites being identified in 1.5-folddosage group and blank group,34 differential metabolites in 5-fold dosage group and blank group,and25 differential metabolites in 1.5-fold dosage group and 5-fold dosage group.The main metabolic pathways of apples affected by cyflumetofen are amino acid metabolism pathway,organic acid metabolism pathway,polyphenol metabolism pathway and lipid metabolism pathway.The effects of cyflumetofen on apple quality is systematic and complex.The production of flavor components and nutrients in apple is composed of several metabolic pathways.Cyflumetofen may regulate both flavor and nutrient changes simultaneously in apple by affecting the activity of key enzymes in these metabolic pathways.