Anthocyanin Accumulation And Synthetic Metabolism Of Fresh Corn And Its Regulation Of Glucose And Lipid Metabolism

Anthocyanin,as a water-soluble pigment is widely found in vegetative organs and reproductive organs of higher plants.It has a great significance towards plant growth and human health.Previous studies have shown that anthocyanin has many biological effects,including antioxidant ability,anti-tumor,anti-inflammatory and anti-diabetes.It plays an important role in health promotion by preventing cancer,cardiovascular disease,diabetes and other chronic degenerative diseases.Black fruit corn,as a new type of special corn,not only has good taste and many nutritions,but also contains abundant anthocyanin resources.However,the researches of fruit corn rich in anthocyanin are not deep enough.Considered of its important nutritional value and health function,it is essential to study the accumulation mechanism of anthocyanin and further develop its potential edible and medicinal functions.In this study,black sweet corn(BSC)and black waxy corn(L1),which were independently bred in China were selected as the research material.Yellow sweet corn(YT28),white waxy corn(L2)and yellow waxy corn(L3)were used as the control groups of BSC and L1,respectively.I studied the changes of anthocyanin components and contents and the relative gene expression levels of black fruit corns during kernel development in order to clarify the key genes controlling the biosynthesis of anthocyanins.This research used transcriptome analysis to investigate the biosynthesis process of anthocyanin in black sweet corns,and also used transcriptome analysis combined with non-targeted metabolome to investigate anthocyanin metabolism in matured black waxy corns,in order to have a better understanding of the anthocyanin metabolism in black fruit corns.By constructing a type II diabetic mouse model and fed with fodders containing black sweet corn,in order to study the regulation effect of fruit corn with abundant anthocyanins contents on glucose and lipid metabolism in diabetic mice.The purpose of this study is to explore the key factors related to the anthocyanin metabolism in fruit corn,and also provide new ideas for the application of black fruit corn in the regulation of human glycolipid,so as to further provide theoretical basis and technical support for the improvement of fruit corn nutritional qualities and development of new products.The main results are shown below:1.The anthocyanin contents of black fruit corns(BSC,L1)were analyzed by high performance liquid chromatography(HPLC).The main anthocyanin varieties in black fruit corn(BSC,L1)contains cyanidin,pelargonidin and peonidin.The main anthocyanins with glucosides contents detected in both black sweet and waxy corns were cyanidin-3-O-glucoside and pelargonidin-3-O-glucoside.The total anthocyanin content showed an increasing trend during kernel development,and changed greatly in the early stage of development and slowed down in the later stages.However,due to the influence of seasonal temperature and photosynthetically active radiation,anthocyanin content in summer was higher than that in autumn.The impact of on pelargonidin under the influence of weather was greater than that of the other two anthocyanins.The expression of major genes in the process of anthocyanin synthesis was analyzed,and it was found that genes such as ANS,DFR,F3 H and CHS played an important role in the regulation of anthocyanin biosynthesis.2.Through the analysis of antioxidant activity in black fruit corns during kernel development,it was found that the black fruit corn had strong antioxidant activity.Overall,the antioxidant capacity of BSC increased during kernel development,while the antioxidant level of L1 decreased.In BSC,the antioxidant level of free antioxidant is higher than that of the bound ones.While in L1,it is just the opposite.The level of bound antioxidant is higher than the free ones.By comparing the cell antioxidant activity with the total antioxidant activity,it was found that cell antioxidant activity was significantly lower than the total antioxidant activity.It is mainly due to the difference in the degree of absorption and utilization of polyphenols.The correlation analysis showed that the content of polyphenols was significantly positively correlated with the antioxidant level during kernel development,and the main phenolic components in black fruit corns,such as cyanidin and ferulic acid,were also positively correlated with the antioxidant capacities.3.Transcriptome analysis was performed on BSC and YT28 during kernel development after pollination of 5 to 20 days.Combine with the composition changes of key metabolite,the results showed that the period with the fastest color changes and highest differentially expressed genes(DEG)was 5-10 DAP.YT28 as the control group,there were 13478 DEGs were found on 5 DAP,including 26 genes related to flavonoid biosynthesis.18 were up-regulated and 8 were down-regulated genes.There were 332 DEGs were discovered by comparing gene expression level of BSC and YT28 of the same growing stages,in which the most anthocyanin biosynthesis related genes were C4 O,DFR,ANS and F3 H.In the transcriptome analysis of sweet corn,the transcription factors which may be related to the regulation of anthocyanin biosynthesis were selected,including LHY protein,MYBR95,pl and MYB3.The first three were up-regulated in the BSC,which may be the stimulating factor of anthocyanin biosynthesis in sweet corn;As a contrast,MYB3 was only expressed in YT28 instead of BSC,which suggested that it might be an inhibitor to regulate the anthocyanin biosynthesis.4.Transcriptome analysis combined with non-targeted metabolome were used to analysis the matured black,white and yellow waxy corn(L1,L2 and L3)on 35 days after pollination.we revealed that the specific metabolites in black waxy maize included 13 anthocyanins and other flavonoid metabolites that were related to the biosynthesis pathway of anthocyanin,such as dihydrokaempferol,naringin chalcone and naringin.The highest content of anthocyanins in black waxy corn was cyanidin-3-O-glucoside.There were 2189 differentially expressed genes between L1,L2 and L3,among which 880 differentially expressed genes were unique to black waxy corn.Among the known key genes in anthocyanin biosynthesis pathway,7 genes were included in the 880 DEGs,including transcription factors r1 and c1,among which 5 structural genes are up-regulated.The up-regulated genes also appeared in black sweet corn study,include F3 H,ANS,CHS and BZ1.The expression of transcription factor r1 was also up-regulated,while c1 expression was not significantly changed.These results suggested that transcription factor R1 might be the stimulating factor in anthocyanin metabolism of waxy corns.5.BSC was selected as the raw material to study the regulation effect of black sweet corn on glucose and liqid metabolism in db/db diabetic mice.After 6 weeks of feeding,the results showed that BSC containing high-dose of feed group could effectively control the weight gain of db/db diabetic mice.Black sweet corn could effectively reduce fasting blood glucose and improve insulin sensitivity in diabetic mice.At the same time,black sweet corn can reduce serum total cholesterol level,improve blood lipid level,reduce LDL-c and regulate serum insulin level in diabetic mice,and the effect was dose-dependent.The pathological symptoms of liver tissue were also reduced after feeding with BSC.