| Broccoli(Brassica oleracea L.var.italica Plench)is a cruciferous vegetable,which is rich in an important secondary metabolites with sulforaphane.Sulforaphane has the effect of detoxifying carcinogens and inhibiting the growth of cancer cells.In this experiment,by analyzing the changes of sulforaphane content,intermediate product content and gene expression in broccoli at different sampling time points after exogenous spraying of methyl jasmonate(40 μmol/L),to explore the molecular mechanism of sulforaphane synthesis by methyl jasmonate on broccoli.The main research contents and results are as follows:1.The effect of methyl jasmonate treatment on the content of glucosinolate and sulforaphane in broccoli was analyzed.The results showed that the content of glucosinolate and sulforaphane in the curd of broccoli treated with methyl jasmonate increased significantly,and the differences between varieties were obvious.After treatment with methyl jasmonate for’Xianglu 3’ in 12 h,the total glucosinolates in the curd increased by1.33 times,the aliphatic glucosinolate content increased by 10.49%,the myrosinase activity increased by 1.89 times,and the sulforaphane content increased 47.6%,reaching 80.28μg/g FW;after 6 hours of treatment with methyl jasmonate,the glucosinolate and sulforaphane content reached the peak,the total glucosinolate content increased by 2.03 times,and the sulforaphane content increased by 46.48% which up to 54.38 μg /g FW.2.The test results showed that under the test conditions,the total sulfur,total nitrogen and methionine content in the broccoli flower have no change significantly during the sampling time after the methyl jasmonate treatment.3.In this test,choosing the flower bulb to analyze the expression of genes related to sulforaphane synthesis.The test results showed that the expression of transcription factors MYB28 and MYB34 were up-regulated about 1 h after treatment with exogenous methyl jasmonate;structural genes MAM1 and MAM3 mainly regulate the extension of aliphatic glucosinolate side chains,while BCAT4 is in glucosinolates The synthesis mainly catalyzes the deamination process of side chain extension.In this experiment,the expression level of MAM1,MAM3 and BCAT4 reached the highest value 1h after methyl jasmonate treatment,and the expression of CYP83A1,SOT18,CYP79F1 was up-regulated after 3-6 h.After treatment,the expression level of SUR1 began to increase in 24 h.The level of up-regulation of CYP83A1 and SOT18 genes is higher than that of other genes: CYP83A1 in’Xianglu3’increased continuously after Me JA treatment,and reached the maximum at 12 h,which was 15 times higher than that of the control;the expression of SOT18 was exogenous After treatment with methyl jasmonate,they all reached the maximum at 6 h,an increase of 4.3times.The expression of aliphatic synthesis-related genes UGT74C1,CYP79F2,and SOT17in’Xianglu 3’was inhibited in the late stage of administration of methyl jasmonate.The genes related to the synthesis of indole glucosinolates were up-regulated,and the time sequence of up-regulation was UGT74B1,CYP79B3,CYP83B1.In’Yanxiu’,6 hours after treatment with methyl jasmonate,the expression levels of CYP83A1 and SOT18 increased by about 4.8times.The expression levels of most genes were lower than that of’Xianglu 3’,and each gene was in two varieties.The expression patterns of MAM3,SOT18,CYP79F1,and indole family gene synthesis related genes MYB34,CYP79B3,CYP83B1,UGT74B1 remained high in the curd,and the treatment of exogenous methyl jasmonate was significant.The expression of these genes in the’Yanxiu’ was promote.Among them,the MY gene maintains a high expression level in the flower,and it has a very significant positive correlation with the content of sulforaphane in’Yanxiu’.In summary,Me JA can promote the synthesis of glucosinolates by increasing the expression of genes related to glucosinolates synthesis.In the two varieties,methyl jasmonate significantly increased the expression levels of CYP83A1,SOT18,and SUR1.The expression of genes is different in time. |
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