Changes And Mechanism Of Stilbenes And Flavonoids In Grapevines Of Summer Black During Storage

Summer Black(Vitis vinifera×Vitis labrusca,Summer Black)is an European-American hybrid,which has strong stress resistance,seedless fruit,purple-black peel and unique flavor,and has become one of the fresh grape varieties in China.After the grapes are harvested,they are pruned and pruned to improve the yield and quality of the grapes.The pruned vines are burned as waste.However,studies have found that pruned vines contain many bioactive components,such as trans-resveratrol,ε-viniferin,catechin and epicatechin.And the amount of these compounds varied with the age of the vine.In this paper,the species and contents of compounds in grapevines of Summer Black were analyzed,the changes of compounds in grapevines during storage and the mechanism of the changes were analyzed,and the reasons of the changes of compounds in grapevines were explored.1.The compounds in the extracts of grapevines were analyzed by high performance liquid chromatography,and 11 compounds were preliminarily estimated,they include one phenylpropanoid compound,five flavonoids and five stilbenes,among the five stilbenes,there are two resveratrol dimers,one resveratrol trimer and one resveratrol 4 polymer.2.The method for the simultaneous determination of four compounds in grapevines were developed using high performance liquid chromatography,the method was used to analyze the contents of resveratrol,ε-viniferin,catechin and epicatechin in the annual cycle of grapevines,the content of compounds and the rate of content change of different length grapevines during shade drying were analyzed.The results showed that the highest concentrations of resveratrol,ε-viniferin,catechin and epicatechin were in October,October,July and June,respectively,the highest contents were 21.56 μg/g,10.31 μg/g,8.06 μg/g and4.21 μg/g respectively.When the length of the vine was 10 cm and the time of storage was10 days,the content of stilbenes varied the most,and the content of resveratrol and ε-viniferin were about 290 and 53 times as much as that of fresh samples,respectively.When the vines were treated at 0.5 cm,the change rate of stilbenes content were the fastest,and the content of stilbenes were the highest in only 4 days.The content of resveratrol and ε-viniferin were about 170 times and 20 times of fresh samples,respectively.According to the experiment,the highest stilbenes levels were recorded in May during the grape growing season.The highest stilbenes content was found in the 10 cm long vines at10 days after harvest,and the highest stilbenes content was found in the 0.5 cm vines at 4days after harvest.3.First of all,the expression of stilbene synthase(STS)and chalcone synthase(CHS),two key genes regulating the synthesis of stilbenes,in 10 cm long grapevines were analyzed by real-time fluorescence quantitative method,the results showed that the expression of STS gene was up-regulated during drought and mechanical damage,and the highest expression was at the 5th day of storage,while the expression of CHS was down-regulated during the whole storage,the expression level of CHS was lower than that of fresh samples.Secondly,western blot was used to analyze the rate-limiting enzyme synthase,which regulates the synthesis of stilbenes,in grapevines during storage.The results showed that the expression level of stilbene synthase in grapevines during storage were higher than that in fresh samples,and had the highest level of expression on Day 8.Finally,the PAL activity of phenylalanine ammonia-lyase in the first step of phenylpropane pathway in grapevines were analyzed.The PAL activity first increased and then decreased during the whole storage,and reached the highest level on the 7th day.The results showed that the increase in stilbenes content in grapevines during storage were due to an increase in the expression of STS,the key gene that regulates synthesis,at the same time,the expression level of stilbene synthase was up-regulated,and finally the content of stilbenes was increased.In this process,STS and CHS were competitive,which led to the down-regulation of CHS expression and the decrease of CHS flavonoids content.As an anti-stress enzyme,PAL participates in the synthesis of stilbenes,and its activity increases first and then decreases.