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Cucumber (Cucumis sativus L.) is a kind of important fresh vegetable. Vegetables are differentfrom food crops, and its attractivity is stronger. Pesticides are easily absorbed by the vegetableorganization after spraying. The accumulation of pesticide residues in the human body can causechronic poisoning, and some pesticides cause DNA damage, teratogenic and carcinogenic effects.More importantly, cucumber and other vegetable crops due to the presence of fresh features,pesticide residues have become the hot issues that the government, the market, and consumers arevery concerned. Propamocarb is a carbamate fungicide, and nearly80percent of the farmers inChina use it against cucumber downy mildew. Due to the production of high-dose use,propamocarb residue of cucumber has been an important issue of cucumber quality. Study aboutlow pesticide residues of cucumber has an important theoretical and practical significance to reduce the use of pesticides, cucumber production costs, improve the quality of cucumber products, protectthe safety of the diet of the people, and enhance the international competitiveness of vegetableproducts in China.In this study, propamocarb residues of32cucumber germplasms of different ecological typeswere determined, three low residual resources and three high residual resources were screened.With low residual resource (D0351) and high residual resource (D9320) as materials, and thecucumber fruit propamocarb residual physiological and molecular mechanism is carried out fromthe point of view of physiology and biochemistry, genomics and proteomics. On this basis, an ABCtransporter protein gene (ABCA19) related to cucumber low propamocarb residue was cloned byRT-PCR, and tissue-specific expression.Test results are as follows:1. This test was carried out for determination of propamocarb residue in32cucumbergermplasm resources of different ecological types. The use of subjective evaluation system andaccording to8%of the rate of selection, the final selection of low propamocarb residue strain2,followed by D0351(pickled) and D0406-15(European greenhouse type); high propamocarb residue strain2, followed by Jinyan No.4(North China type) and D9320(South China type).2. Using Solexa technology, differentially expressed genes were identified under propamocarbtreatment of cucumber fruit through the method of comparative genomics. The results found thatdifferentially expressed genes had a total of14,530, in line with FDR≤0.001and differences in2times more than a total of731genes.546genes were up-regulated expression, accounting for74.7%, and185genes were down-regulated expression, accounting for25.3%. Under propamocarbstress, differentially expressed genes are mainly four categories, the first category is mainly relatedto pesticide detoxification genes, including the multidirectional resistance protein gene (PDR),multidrug resistance protein gene (MRP), glutathione transferase gene (GST), ABC protein gene(ABCT), cytochrome P450(CYP), phenylalanine ammonia solution enzyme gene (PAL), etc. Thesecond type mainly includes some transcription factors, including TCP transcription factors, GATAtranscription factor, WRKY transcription factor30etc. Third category mainly includes transportand signal related genes, including sucrose transport genes (SUT), transaminase (AMT), succinatedehydrogenase (SUD), etc. Fourth category mainly includes stress stimulus related genes, includingperoxidase gene (POD), cysteine synthase gene (CYS),70kDa heat shock protein gene (HSP), etc. 3. GO analysis showed that differentially expressed genes involved in several biologicalprocesses, including cellular components, molecular function and biological processes. Cell part,catalytic activity and metabolic process occupy mainpart respectively.4. In propamocarb stress, differentially expressed genes involved90Pathway. The Pathway ofP≤0.05and Q≤0.5had a total of eight. Glutathione metabolism pathway (Glutathione metabolism)is a significant enrichment pathway among them, and further analysis showed that six genes ofglutathione metabolism were all up-regulated expression.5. Using MALDI-TOF-TOF technology,18differentially expressed proteins of highabundance were identified with Mascot software.13protein spots showed up-regulated expression,which were Spot1,6,8,10,11,12,13,14,15,16,17,18and19;5protein spots showeddown-regulated, Spot2,3,5,7and9. The main function of the differential protein spots wasdetoxification, energy and transport, protein synthesis, and resistance to stress reaction.6. In this study, the cucumber ABC transporter gene (ABCA19) was cloned, and its proteinstructure was predicted. The entire length sequence of this gene was921bp encoding306aminoacids. The homology of ABCA19amino acid sequence between cucumber and arabidopsis was 56%. Encoding the protein of this gene contained the ATP/GTP binding region [ATP/GTP-bindingsite motif A (P-loop)]. Gene expression analysis showed that, ABCA19responded rapidly underpropamocarb stress, mainly expressed in the early treatment. At the same time, the gene expressionfound that the leaf had the highest expression level, and stem had the lowest expression.
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