Study On Mechanism And Inhibition Blue Discoloration Of Radish Root

Radish root will occur internal blue discoloration during storage,which reduces the quality,consumer purchases and economic value of radish root.At present,the mechanism of internal blue discoloration of radish root is not clear,which inhibits the research and development of prevention technologies.This paper studied the internal blue discoloration of different varieties of radish root and the stability of blue pigment of radish root.In recent years,transcriptomics and metabolomics have been widely employed to elucidate changes in genes and metabolites in plants.We here in performed liquid chromatography–tandem mass spectrometry（LC-MS）to identify differentially expressed metabolites and pathways in white radish（WR）and blue radish（BR）;in addition,transcriptomics was used to assess biosynthetic and regulatory genes,and data were validated by quantitative real-time polymerase chain reaction（q RT-PCR）.Finally,the effect of modified atmosphere packaging treatment on key factor enzyme activity and transcription level expression clarified the mechanism of modified atmosphere packaging inhibiting blue discoloration of radish root.The specific research results are as follows:1.The blue discoloration of radish root during storage were investigated.The blue discoloration of different varities of 16 Chinese radish root（LB05-244,LB05-240,LB05-250,SWZ17-125,LB05-227,SWZ17-114,SWZ17-125,SWZ17-11,SWZ17-251,SWZ17-119,SWZ17-87,LB05-253,SWZ17-132,LB05-245,Piton radish,and Dense radish）and stability of blue pigment under different light,p H,and temperature conditions were investigated.The results showed that the blue discoloration of LB05-244 and LB05-240 were highest and blue discoloration of Piton radish,and Dense radish were lowest by blue intensity and blue area ratio of cluster ananlysis of 16 radish root varities.The degradation of blue pigment occurred faster under blue light than under green,red,and white light and darkness.Blue pigment degraded fastest at p H values of 13 and 1.The blue pigments in radish exhibited thermal instability,with complete degradation occurring in 5 or 10 min at 90 or 100 ^oC,respectively.In conclusion,variety affected the discoloration.The pigment exhibited light,p H and thermal instability.2.The internal blue discoloration of radish roots（Raphanus sativus）during storage affects their quality.We here performed transcriptome and metabolome profiling to investigate the mechanisms underlying the bluing of radish roots during storage.On comparing white radish（WR）and blue radish（BR）,we identified14,171 differentially expressed genes（upregulated:7,383,downregulated:6,788）and 145 differentially accumulated metabolites（upregulated:117,downregulated:28）.Functional annotation analysis and metabolome profiling revealed that the blue discoloration of radish roots was promoted by high content of glucosinolates,oxidation system（ROS,CAT,POD）or low reduction system（GSH,GPX,APX,GST,ASA）.Our results provide new insights into the underlying metabolic causes of the blue discoloration of radish roots and report candidate genes and metabolites involved in blue compound biosynthesis.3.Oxidative stress in radish root could cause blue discoloration and decrease the vegetables quality.The effect of oxygen concentration applied during short-term storage of radish roots on color prosperity,content of 4-hydroxyglucobrassicin（precursor of blue component）,ROS（O₂-and H₂O₂）,ascorbic acid（As A）,glutathione（GSH）,activity and genes expression of enzymes（CAT,GPX,APX,POD）were determined after the harvest and their change monitored after 3 and 6 day storage.The results suggested that radish root packaged with 10%O₂ prevented phenomenon of blue discoloration of radish root,which was because 10%O₂ packaged maintained color,increased content of 4-hydroxyglucobrassicand and reduction system（content of ascorbic acid and glutathione）,and decreased oxidation system（O₂-and H₂O₂）.