Study On The Regulation Of Stipe Elongation And Compound Preservation Technology Of Flammulina Filiformis After Harvest

Due to the strong respiration metabolism after harvest and the lack of obvious protective tissue on the surface,Flammulina filiformis is prone to double deterioration of sensory and nutritional quality.Stipe elongation,as the main manifestation of sensory deterioration,is particularly serious in the middle and late stages of storage,which directly decreases the commercial value of F.filiformis.At present,there are few researches on the stipe elongation of F.filiformis after harvest and the effect of different preservation technologies on the stipe elongation of F.filiformis is still unclear,and its exact regulation mechanism has not been confirmed.In order to clarify the regulation of stipe elongation after harvest,the research used the white strain of F.filiformis as the research material to determine the specific position of the stipe elongation after harvest,screen and construct a regulatory model of stipe elongation,and use transcriptomics technology to explore the regulation mechanism of stipe elongation.At the same time,this article put forward a new type of compound preservation method of calcium lactate combined with nano-packaging on the basis of experimenting with a variety of fresh-keeping methods for F.filiformis,which can improve the storage quality and prolong shelf time of F.filiformis.The specific results are as follows:1.The specific stipe elongation position of F.filiformis after harvest was determined by marking method.The experiment found that 0-6 mm at the top of the stipe was the elongation region of F.filiformis after harvest.Among them,the elongation speed of 0-2 mm was the fastest,and the elongation of 2-6 mm was slower.Through screening a variety of fresh-keeping technologies,the experiment found that the composite preservative film treatment could delay the stipe elongation of F.filiformis to the greatest extent,which could be used as a regulatory model to delay the stipe elongation after harvest.The stipe extension length of F.filiformis packed with PE film was the longest,and can be used as the corresponding control group.2.Transcriptome technology was used to sequence and analyze the stipe elongation tissues of the delayed stipe elongation group and the control group.The results showed that1292 genes were up-regulated and 1427 genes were down regulated.The GO and KEGG enrichment analysis of differentially expressed genes showed that most of the genes in the ribosome,proteasome,cell cycle and other pathways were down-regulated;The analysis of transcription factors revealed 46 types of 1011 differentially expressed genes,of which 15 genes were down-regulated and 5 genes were up-regulated in the b ZIP transcription family involved in stipe elongation regulation;RT-PCR and transcriptome sequencing showed the roughly same gene expression,verifying the accuracy of transcriptome sequencing.Among them,glucan synthase(g5946),glucanase(g7565),chitin synthase(g5217),and γ-amylase(g3457)were all down-regulated.It is speculated that the molecular mechanism of the composite membrane inhibiting the stipe elongation of F.filiformis may have two reasons.On the one hand,the gene expression of cell division-related pathways was down-regulated,which slowed cell division in the stipe elongation zone;On the other hand,the expression of genes related to cell wall expansion was down-regulated,which affected cell wall expansion,thereby inhibited cell growth.3.The fresh F.filiformis was treated by calcium lactate immersion,nano-packaging,and calcium lactate combined with nano-film packaging.After 20-day low-temperature storage,the influence of different treatment methods on the main quality parameters of F.filiformis was analyzed.Calcium lactate treatment was better than nano-packing treatment in inhibiting cap opening,stipe elongation and delaying the decrease of soluble solid and soluble protein content of F.filiformis.While nano-packaging treatment was more effective in retarding the decline of whiteness value,reducing the accumulation of malondialdehyde and suppressing flavor deterioration of F.filiformis.However,there was no significant difference between calcium lactate treatment and nano-packaging treatment in the maintenance of total phenol content.The compound preservation treatment can combine the fresh-keeping advantages of calcium lactate treatment and nano-film packaging,effectively maintain the content of soluble protein,total phenols and other nutrients,reduce respiratory intensity and membrane lipid peroxidation,and better improve the storage quality of F.filiformis.In conclusion,by constructing a stipe elongation delay model of F.filiformis,we used transcriptomics to systematically analyze the mechanism of the composite preservative film delaying the stipe elongation,and proposed a compound preservation method to improve the storage quality of F.filiformis by combining calcium lactate treatment with nano-packaging.The research results can provide a theoretical basis for the regulation of stipe elongation and fresh-keeping of F.filiformis after harvest.