Study On Effect From UV-C Treatment On Anthocyanin Biosynthesis And The Cloning Of Anthocyanin Acyltransferase Of Red Cabbage

Anthocyanins are important pigment which imparts diverse colors vary from pink,red,and purple to blue to plant.In addition,anthocyanins have pro-health function.However,anthocyanins are instable and easy to degenerate because of light,temperature,circumstance pH.Recent articles show that acylated anthocyanins are more stable and have higher antioxidant capacity than non-acylated compounds.Therefore acylated anthocyanins are potential food additives.Red cabbage(Brassica oleracea L.var.capitata f.rubra DC.)is a rare vegetable variety that is rich in anthocyanin.It exhibits bright purple-red color and tastes crisp.It is tend to be processed as fresh-cut vegetable.Ultraviolet C(UV-C)is a kind of common non-thermal sterilization technology which is used in fresh-cut processing.Studies have indicated that UV-C can delay senescence,reducing decay and improve antioxidant capacity and the content of flavonoids such as anthocyanins.In our research,we use red cabbage to study the effect of UV-C treatment on anthocyanins biosynthesis,antioxidant capacity and the gene expression in anthocyanin metabolism to enclose the mechanism of UV-C mediate anthocyanin.We also clone the acyltransferase gene and study the protein property.The research results are as follows.(1)The 37 varieties of red cabbage we collected to detect their color and anthocyanin composition.The results show that each variety owns its special color and the anthocyanin composition significantly varies from one to others.18 anthocyanin compounds were identified from red cabbage,and they are all cyanidin derives.27 had the highest content of anthocyanins.Thus we picked the 27 to do further study.(2)Fresh-cut red cabbage(variety 27)treated with dose of UV-C(0,1.0,3.0,5.0 kJ/m~2)were stored for 1,4,8 and 12 days.It turned out that 4 new anthocyanins were detected from UV-C treated samples named Cy-3-O-glucoside-5-O-glucoside,Cy-3-O-(p-coumaroyl)-diglucoside-5-O-glucoside,Cy-3-O-(feruloyl)-glucoside-5-O-glucoside and Cy-3-O-(sinapoyl)-glucoside-5-O-glucoside.(3)The total anthocyanin contents in 1.0 and 3.0 kJ/m~2 UV-C treatment were markedly increased,while the total anthocyanin content reduced gradually during the course of storage following treatment with 1.0 kJ/m~2 UV-C.Treatment with 3.0 kJ/m~2 UV-C caused the total anthocyanin content peaking at 8days of storage.UV-C treatment caused different impact toward individual anthocyanin.The accumulation of Cy3G5G,Cy3(fe)G5G and Cy3(si)G5G increased as the intensity of UV-C dose increased.On the contrary,higher UV-C radiation doses resulted in decreased accumulation of Cy-3-O-diglucoside-5-O-glucoside,Cy-3-O-(feruloyl)-triglucoside-5-O-glucoside,Cy-3-O-(sinapoyl)-triglucoside-5-O-glucoside and Cy-3-O-(sinapoyl)-diglucoside-5-O-glucoside).(4)The total antioxidant capacity(TCA)of 3.0 kJ/m~2 was significantly higher than control treatment.The TCA also increased following with 1.0 kJ/m~2 but lesser extent.A decline in the TCA value was observed with 5.0 kJ/m~2 but not significantly.(5)The expression level of most anthocyanin biosynthesis and regulatory gene were slightly up-regulated by different dose of UV-C.Except DFR,ANS and TT8,most of the genes peak at the 12day.3.0 kJ/m~2 treatment markedly increased GT and PAP1 by 20-fold and 28-fold respectively after one day storage.In conclusion most of the biosynthesis genes showed most pronounced increased with 3.0kJ/m~2.(6)The cloned red cabbage anthocyanin acyltransferase gene(BoSCPL)belongs to the typical SCPL family and can catalyze anthocyanin acylation modification according to the bioinformation analysis.In conclusion,UV-C treatment has an important effect on anthocyanin,which can increase the anthocyanin contents and compounds and antioxidant capacity of fresh-cut red cabbage.UV-C can also up-regulate the anthocyanin biosynthetic and regulatory genes which may result in the accumulation of anthocyanins.3.0 kJ/m~2 is the most appropriate dose to improve the anthocyanin biosynthesis in fresh-cut red cabbage.