Effect Of Glycine And Nitrate On Antioxidant And Polyphenol Metabolism In Pakchoi

In order to explore the antioxidant difference among cultivars about uptake of glycine,the effect of Gly/NO₃-N on antioxidant and polyphenols metabolism in pakchoi?Brassica campestirs ssp.chinensis?L.?Makino var.comMunis Tsen et Lee?,experiments were carried on from the following aspects.Firstly,optimal method of polyphenol-extraction of pakchoi was established by single-factor and orthogonal experiment,which was used for the polyphenol-extraction in the next experiments.Then,the difference of antioxidant among cultivars responding to glycine was tested under the condition of hydroponics.Meanwhile,suitable cultivar and it's corresponding glycine concentration were chosen.Finally,investigated the change of antioxidant and polyphenol metabolism in the cultivar chosen out by the treatment of Gly/NO₃-N also under the condition of hydroponics.Results were as follows.1.Single-factor and orthogonal experiment were used to explore the influence of methanol concentration,extraction time,extraction temperature and auxiliary methods?ultrasonic,microwave,table?on extraction yield of total polyphenols in pakchoi with N0₃-N as the contrast.Result showed that the ideal conditions for pakchoi were with ultrasonic assistance?200W,53Hz?,50% methanol?v/v?at 50? for 30 min,which the extraction yield separately increased by 20.96% and 6.20%,compared with normal extraction method and single-factor condition?ultrasonic assistance?200W,53Hz?,50% methanol?v/v?at 40? for 60 min?.2.The antioxidant of 9 pakchoi cultivars?‘wuyueman',‘xiawang',‘aijiqing',‘yanchun',‘huawang',‘zhongjiqing',‘xinxiaqing5',‘chanzheng2',‘aikangsuzhouqing'?responses to glycine of three concentation?2.5mM?5mM?10mM? with NO₃-N as thecontrast under the condition of aseptic hydroponic culture.Results showed that cultivars were classified into three categories by the means of cluster analysis.The first include‘Huawang'only which the antioxidant ability performed best under the supply of glycine,while the second and third were relatively less.Besides,we also figured out the effects of different glycine concentration on antioxidant among cultivars,for example,‘Huawang'showed the high antioxidant ability under the concentration of 10 mM and low in 2.5mM.3.The effect of NO₃-N and glycine on yield and antioxidant of pakchoi were tested under treatments of Gly/NO₃-N=3:1,Gly/NO₃-N=1:1,Gly/NO₃-N=1:3 with NO₃-N as the contrast.Results showed that compared with nitrate CK,the treatment of Gly/NO₃-N notably increased the antioxidants like polyphenols,flavonoids,GSH and Vc and activity?FRAP and DPPH value?,meanwhile guarantee the biomass in pakchoi which was quite important.Results also showed that the contents of all antioxidants changed the same way,that is,presenting a trend of increased first and decreased later with the increasing supply of glycine that reached the peak under the treatment of Gly/NO₃-N?1:1? and the lowest under Gly/NO₃-N?3:1?.Equally important,we found that the contents of flavonoids were extremely affected by Gly/NO₃-N comparing to other antioxidants,which increased by 107.10% contrasting with CK.4.Importantly,it showed that the content of Phe increased by 33.79%-86.32% and also the synthetase activity excepting 4CL like PAL,C4H,CHS and CHI strikingly promoted and the catabolic enzyme activity of DFR restrained by the treatment of Gly/NO₃-N,compared with CK.In addition,with the correlation analysis method,we carried out the correspondence between polyphenols and flavonoids with Phe,PAL,C4H,CHS and CHI which were positive correlation,while negative correlation with 4CL and DFR.In conclusion,Compared with normal extraction methods,the total polyphenols yield extremely increased by 20.96%.The antioxidant activity was strikingly enhanced under the treatments of Gly/NO₃-N.It's the substance basis that Polyphenols metabolism-strengthened,which increased the total polyphenols and antioxidant activity,under Gly/NO₃-N.