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Accumulation Of Phenolic Substances And Differential Expression Of Catechin Biosynthesis-related Enzyme Genes In Lotus Roots

Posted on:2020-01-15Degree:MasterType:Thesis
Country:ChinaCandidate:B X ZhouFull Text:PDF
GTID:2370330578469773Subject:Food Science
Abstract/Summary:PDF Full Text Request
The phenolic substances detected in lotus roots are catechol,gallic acid,catechin,caffeic acid,coumaric acid,resveratrol,lutidine,epicatechin,and chlorogenic acid.The edible part of lotus root can detect more catechins,which are the more representative phenolic substances in lotus phenolic substances,and have strong free radical scavenging and antioxidant capacity.The composition analysis and activity evaluation of lotus phenolic substances have attracted extensive attention,but little research has been done on the accumulation of phenolic substances and the mechanism of catechin biosynthesis.This topic uses lotus root(" Elian No.5 ")as the material,based on appearance,browning degree,total phenolic content and monophenol composition and other indicators,study the changes of phenolic substances in different growth stages of lotus root,compare the differences of phenolic substances in different harvesting stages,and the effects of different storage methods on their phenolic substances after harvesting,and to clarify the accumulation of phenolic substances in lotus roots;The expression patterns of catechin biosynthesis-related enzymes were screened by transcriptome sequencing and real-time fluorescent quantitative PCR analysis.The accumulation of phenolic compounds and the biosynthesis mechanism of catechins were preliminarily clarified.The research results are as follows:(1)Changes in lotus phenolics during different growth and harvest periods:The growth period of lotus root is divided into six periods,namely G1-G6.the early growth stage(G1-G3)is the rapid expansion period of lotus root tubers,and its total phenolic content,monomeric phenol(gallic acid,gallic catechin,catechin)content increases rapidly,this period is rapid accumulation period of phenolic substances.The harvesting period is divided into five periods,namely H1-H5.In the third harvesting period(H3),the content of phenolic substances and monomeric phenols was relatively high,and the browning degree was low.The third harvesting period(H3)can be determined as the best harvesting period of lotus root based on the evaluation of appearance and activity of phenolic substances.(2)Effects of different storage methods on lotus phenolics after harvest:low temperature(4?)can effectively inhibit the browning and total phenolic content of fresh-cut lotus root tablets,delay the decrease of gallic acid catechin and gallic acid content,inhibit the increase of catechin content,gallic acid and gallocatechin may be used as substrates Participate in the browning process;phenolic extract Of fresh-cut lotus root may have new substances synthesized at room temperature(20?),and the specific components need further identification;High concentration of CO2 modified atmosphere packaging effectively inhibited the browning and total phenolic content of Fresh-cut slices,induced the synthesis of gallic acid,and had no obvious effect on the content of catechin and gallocatechin.(3)Differential expression analysis of catechin synthesis related enzyme gene:during the growth and development of lotus root,the expression patterns of PAL2 and CHS4 were positively correlated with the content of lotus phenol ics and catechins,and may be responsible for the synthesis of lotus phenolic precursors.ANR2 showed a continuous upward trend during the whole growth period,and its expression level was the highest in H3 stage,which was positively correlated with the high content of lotus phenolics in H3,which may regulate the biosynthesis of epicatechin and epigallocatechin;Low temperature down-regulates the expression of PAL1/2,4CL1,CHI1,CHS4/5,and CHI1,thereby inhibiting the synthesis of lotusphenol precursors,and further down-regulating the expression of LARI,inhibiting the colorless cyanidin(directly before catechin)Synthetic catechin;High concentration of CO2 down-regulated the expression of 4CL1,PAL1,and PAL2,thereby inhibiting the synthesis of phenolic precursors and delaying the synthesis of lotusphenols.
Keywords/Search Tags:lotus root, phenolic substances, catechin, biosynthesis, gene expression
PDF Full Text Request
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