Study On Lignification Mechanism Of Post-harvest Chinese Flowering Cabbage With High Oxygen Modified Atmosphere Packaging

The great flavor of the Chinese flowering cabbage is very popular with the people in South China.Cold storage of Chinese flowering cabbage can prolong storage time,but lignification will happen during storage,which is characterized by hollow stems and tough taste.Inhibition of lignification by high oxygen modified packaging has been reported in green asparagus and Agaricus bisporus.In this study,we used pure oxygen and air?control group?to package Chinese flowering cabbage,and tested the physiological and biochemical indexes and transcriptome of Chinese flowering cabbage at different storage periods.Exploring the effect of high oxygen modified atmosphere packaging on lignification of cabbage and physiological metabolism changes during lignification.The main findings are as follows:The content of cellulose,lignin,cell wall and hardness of Chinese flowering cabbage with high oxygen modified atmosphere packaging were lower than that of the control group.Cellulose content is highly correlated with hardness,lignin content with hardness and cellulose content with lignin content are also.The high oxygen environment maintained for 4 days in the high oxygen packaging bag.In the first 4 days,the respiration rate of Chinese cabbage with high oxygen packaging was higher,and there was no significant difference in H₂O₂,after 4 days,the content of H₂O₂ rose sharply in control group.The activities of LAC and POD in two treatments increased first and then decreased,but in general,the LAC and POD activities of control group were higher.0d,4d,and 8d different packaged Chinese flowering cabbage samples were sent for sequencing.A large amount of sequencing data was obtained for each sample.The base sequencing error rate was less than 0.04%.Q20 was higher than 96%and Q30 was higher than 91%.The quality of base sequencing was high.According to the analysis of Brassica_napus,Total maps were all over 84%,unique maps were over 80%,and Multi maps were all below 4%.The overall reference contrast is high.The three parallel gene expressions in the sample are highly correlated,the principal component analysis is similar,and the gene expression correlation between the samples is low,and the principal component analysis is different.The overall distribution of gene expression in each sample was similar.The transcriptome analysis revealed that the 4d and 8d Chinese flowering cabbage had significant differences in their expression compared to 0d.Compared with the 0-day sample,two different packaged Chinese flowering cabbage was enriched in the down-regulated pathway:photosynthetic,ATP biosynthetic process,active ion transmembrane transporter activity,carbon metabolism,nitrogen metabolism and so on,but enriched the up-regulated MAPK signal pathway.Compared with the 0 day,the control group was enriched up-regulated pathway for synthesis and metabolism of spermine and spermidine.Low temperature caused a decline in the overall metabolism of Chinese flowering cabbage,and it was also a stress that triggered the defense mechanism of the plant.On the fourth day,compared to the control group the Chinese flowering cabbage with high oxygen modified atmosphere packaging was enriched in the down-regulated pathway:Biostimulation response,defense response,cell wall tissue biosynthetic pathway.On the eighth day compared to the control group the Chinese flowering cabbage with high oxygen modified atmosphere packaging was enriched in the up-regulated pathway:Methyltransferase activity,phenylpropanoid biosynthesis and alanine metabolic pathways.The Chinese flowering cabbage under high oxygen modified atmosphere packaging was subjected to lower stress in the early stage of storage,and the production of lignin was less,but the production of lignin began to increase at the later stage of storage.