Profiling And Relative Gene Expression Of Glucosinolates In Radish(Raphanus Sativus L.)

Glucosinolates(GLS)are an important family of bioactive secondary metabolites found mostly in the Brassicaceae family.Glucosinolates and their breakdown products are associated with not only the insect-resistant and sterilization chemoprevention but also the factors influencing the sharp flavors,bitter and strong smells of crucifer vegetable.The sharp flavors is caused by the isothiocyanates derived from the glucosinolates in radish.In addition,epidemiological studies have shown that eating cruciferous vegetables can reduce the risk of cancer.many studies on glucosinolates have been conducted in some species of cruciferae and arabidopsis thaliana,but there is less information about glucosinolates in radish root.What's more,the detailed research of single species of glucosinolates play an important role in analysis of genotype and ecological studies.In this study,Glucosinolates content and profile were investigated and analyzed their gene expression.The aim of this study work was to investigate the key genes involved in glucosinolates biosynthesis pathways and find the source-sink relationship of glucosinolates in radish.It was also to provide basic theory for controlling glucosinolates quantity and quality in certain tissue or organ.Main results are obtained as follows:1.Five aliphatic glucosinolates(Glucoraphenin,n-Heptyl,Glucosativin,Glucoerucin,Glucoraphasatin)and four indole glucosinolates(4-hydroxyglucobrassici,Glucobrassicin,4-Methoxyglucobrassicin,Neoglcobrassincin)were identified and quantified using LC-MS and HPLC.The mean content of glucosinolates was 10.56 umol·g-1 DW in 45 varieties of radish.Through analyze by the principal component analysis to evaluate the principal single glucosinolates.Proved that the total glucosinolates content have positive correlation with Glucobrassicanapin.Glucoerucin and Glucoraphasatin contents.Moreover,there is strong correlation between glucosinolates of the same family.2.In this study,glucosinolates profiles,molecular mechanism of synthesis and their accumulation at different developmental stages were investigated.Five aliphatic glucosinolates and four indole glucosinolates were identified and quantified.The results showed that glucosinolates profiles were different in organs of radish.Glucosinolates content was highest in the skin and lowest in the leaf,however,most of these glucosinolates were aliphatic.Moreover,the glucosinolates content differed significantly at different growth stages.The correlation between expression profile of genes and glucosinolates profile had a significant differences at different levels.The levels of AOP2 and CYP81 gene families were more strongly associated with the change of glucosinolates content,This indicated that AOP2 and CYP81 gene families might be key genes that regulates the synthesis of glucosinolates.Furthermore,almost all the genes were highly expressed in the leaf and skin while least expressed in the flesh,this is an indication that in radish,glucosinolates could mainly be synthesised in the leaf and then translocated to the roots.The data disclosed the regulation mechanism of glucosinolates synthesis and accumulation from molecular level.3.The effects of sulfur fertilization on GLS contents and expression profile of genes in radish roots was studied in hydroponic conditions.The result showed that sulfur fertilization promoted the accumulation of aliphatic GLS,indole GLS and total GLS significantly.It should arouse our concern that aliphatic GLS was always the main GLS and the proportion of indole GLS content increased with the concentration of sulfur fertilization.The change of the total GLS contents had obvious positive correlation with the change of Glucoraphasatin.There was different correlation between expression profile of genes and glucosinolates profile at different sulfur fertilization.The results show that the interaction of SUR2 and TGG4 had correlation with the change of total GLS.This experiment provided the effects of sulfur fertilization on regulate GLS contents and provided policy basis for sulfur fertilization using.