| Ascorbic acid(L-Ascorbic acid,AsA),also known as vitamin C,is a water-soluble antioxidant widely presenting in animals and plants(Gallie 2013).AsA synthesis in Plants can not only supply a rich source of vitamin C for human and some animals,but also maintain the normal growth and metabolism of plants(An 2004).In recent years,the gene engineering technology is widely used to improve ASA contents in crops.It can not only help to obtain high level of vitamin C,but also enhance the resistance of plants.And it has an important influence on the improvement of agricultural products nutritional quality.This study explores the correlations between the content of ascorbic acid and related gene expression under different treatments and provids a theoretical basis for high-quality breeding of non-heading Chinese cabbage.The main results are as follows:1.This study aims to acquaintance the changes of ascorbic acid content in non-heading Chinese cabbage under the stresses,furthermore to find out the the key genes involved in the regulation of ascorbic acid.'Suzhouqing' was used to investigate the content of AsA and the expression of the genes related to the AsA biosynthesis and metabolism.The results showed that:the trends of AsA contents under the two treatments were all increasing at first and then decreasing.The changing trends of GME and GPP relative expressions were consistent with that of AsA content under hydrogen peroxide stress,while the changing trends of PMM,GME and VTC2 relative expressions were consistent with that of AsA content under water logging stress.So it indicated that GME gene may be the key gene of this two kinds of stresses.2.'Suzhouqing' was used as the material under the treatments of ABA and ethylene respectively with different concentrations(0,10,50,100 and 200 ?mol·L-1).This study aims to acquaintance the changes of ascorbic acid content in non-heading Chinese cabbage under the hormone treatments,furthermore to find out the the key genes involved in the regulation of ascorbic acid.The results showed that:the trend of As A content was different along with these concentrations,and the changing trend of PMM relative expression was consistent with that of AsA content under the treatment of ABA.What's more,under the treatment of ethylene the AsA content was increasing at first and then decreasing.The changing trend of GPP relative expression was consistent with that of AsA content under the treatment of ethylene(10?mol·L-1 and 50 ?mol·L-1),while changing trend of PMM and GPP were consistent with that of AsA content under the treatment of ethylene(100?mol·L-1 and 200 ?mol·L-1).So it indicated that PMM and GPP may be the key genes involved in AsA biosynthetic pathway under ABA and ethylene treatments respectively.3.In this experiment,the full length of GDP-D-mannose-3',5'-epimerase was cloned from non-heading Chinese cabbage.The amino acid sequence was analysed by bioinformatics.And we constructed the gene scilence vector BcGME-PCVA.The study indicated that the ORF length of BcGME was 1137 bp,encoding 379 amino acids.Themolecular weight of BcGME was 42.97x103,pI value was 5.84,and the molecular formula was C1907H2949N519O570S22,belonging to the unstable protein.BcGME grand average of hydropathicity was-0.440,which was the hydrophilic protein.Subcellular localization predicted that the protein was distributed in cytoplasm.The similarity of amino acid sequence between BcGME and most of the cruciferae were more than 90%.Phylogenetic analysis showed that BcGME was close to Brassica rapa subsp.Pekinensis,Brassica napus,and Arabidopsis thaliana.What's more,the tertiary structure of BcGME and AtGME were similar.So we speculated that the gene BcGME plays a key role in ascorbic acid synthesis pathway. |
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