The Effect Of Different Storage Conditions On Fresh-cut Lotus Root Browning And Expression Regulation Of PAL、PPO And POD

Lotus root(Nelumbo Nncifera Gaertn)is an important aquatic vegetable with high nutritional value and medicinal value.Because of its convenience,fresh and high edible rate,fresh-cut lotus root has been developed into a new product pattern.However,The browning is easy to take place during processing,storage and transportation of fresh-cut lotus root,which directly affect the sensory properties and the intrinsic quality of the products.Previous researches mainly focused on browning controlling method for lotus root,but there is a very small number of report on the molecular mechanisms of lotus root browning,and the research on molecular mechanisms of will can provide to some degrees the theoretical basis for the research of lotus root browning controlling method.In this paper,the effect of different storage conditions(temperature and modified atmosphere packaging)on browning degree,total phenol content,PAL,PPO and POD activity of fresh-cut lotus root were analyzed.by physiological and biochemical methods The results showed that the higher the temperature,the more serious the Browning,and compared with other gas packaging conditions,100% CO2 could significantly delay the browning of fresh-cut lotus root.It might because that low temperature and high concentration of CO2 passive PAL,PPO and POD enzyme,and reduced phenol content,which led to the decrease of the rate of phenol oxidation and then the delay of the browning of fresh-cut lotus root.Further more,different expression of fresh-cut lotus root browning related gene during different storage conditions(temperature and modified atmosphere packaging)were analysed.The results showed that:(1)Two NnPAL,two NnPPO and seven NnPOD genes were isolated using RNA-seq.Phylogenetic analysis showed that NnPAL,NnPPO and NnPOD genes were clustered with different homologues from solanum tuberosum,Arabidopsis thaliana Malus hybrid cultivar and Betula platyphylla,respectively.(2)The effect of different temperature on expression of NnPAL1,NnPPOA,NnPOD1,NnPOD2,NnPOD3,NnPOD4,NnPOD5 and NnPOD6 parallelled with change of the PAL,PPO and POD activity and lotus root browning.Thus it was preliminar clear that NnPAL1,NnPPOA,NnPOD1,NnPOD2,NnPOD3,NnPOD4,NnPOD5 and NnPOD6 genes might participate in fresh-cut lotus root browning in high temperature.It was possible that NnPAL1,NnPOD2,NnPOD5 and NnPOD6 might play a leading role in browning during early storage,while NnPPOA,NnPOD3 and NnPOD4 were involved in browning during the whole storage period.(3)The expression of NnPAL1,NnPAL2,NnPOD4,NnPOD5 and NnPOD7 were suppressed by high concentration of CO2.,which parallelled with the change of the PAL,PPO and POD activity.Thus it was preliminar clear that NnPAL1,NnPAL2,NnPOD4,NnPOD5 and NnPOD7 might participate in fresh-cut lotus root browning with modified atmosphere packaging using high concentration of CO2.And NnPAL1 and NnPAL2 might play a leading role during late storage,NnPOD5 mainly at the middle storage,while NnPOD4 and NnPOD7 were involved in browning during the whole storage period.In the paper,the mechanism of fresh-cut lotus root browning under different storage conditions(temperature and modified atmosphere packaging)were researched,and the browning related genes were screened,which will provide basic research for the molecular of fresh-cut lotus root browning.