Regulation Mechanism Of Nanocomposite Packaging On Lignification Of Flammulina Velutipes

Lignification can cause Flammulina velutipes browning,increase of firmness,and loss of nutrients during storage,which will seriously affect its edible and commercial value.In order to solve this problem,a new type of polyethylene-based material consisting of nano-Ag,nano-Si O2 and nano-Ti O2 was prepared and it was applied to the storage of F.velutipes.In order to explore the effect and clarify the mechanism of nanocomposite packaging(NP)on lignification,physiological and biochemical indexes and transcriptome of F.velutipes during storage were determined.These results provided a theoretical basis for the application and promotion of NP on postharvest F.velutipes preservation.More information on each research chapter was shown as follows:1.In comparison with normal polyethylene packaging(PE)and no packaging(CT),NP reduced the deposition of lignin by suppressing the activities of phenylalanine ammonia lyase(PAL),cinnamate 4-hydroxylase(C4H)and4-coumarate-Co A ligase(4-CL),which involved in phenylpropanoid pathway.As a result,NP effectively prevented the decrease of L^*value,the increase of firmness and maintained a better microstructure.In addition,NP reduced the accumulation of reactive oxygen species(ROS)and Ca²⁺,the increase of deoxyribonuclease(Dnase),Ribonuclease(Rnase)and Caspase-3 activities by maintaining higher content of endogenous hydrogen sulfide(H2S).Therefore,NP postponed the programmed cell death(PCD)and the accumulation of lignin in F.velutipes.2.High-throughput sequencing was performed on F.velutipes with different packaging at the end of storage.The RNA quality of all samples was qualified and met the standard of library construction.The GC content of high-throughput sequencing data was greater than 53.31%,and the percentage of Q30 was greater than95.73%.Therefore,the quantity and quality met the requirements of database construction.The results of differentially expressed genes screening showed that compared with PE,a total of 379 significantly differentially expressed genes were identified in F.velutipes packaged with NP,including 161 up-regulated genes and 218down-regulated genes.3.The results of GO enrichment and KEGG pathway enrichment analysis showed that,compared with PE,NP could significantly regulate lignin catabolism,oxidative stress,hydrogen peroxide catabolism,energy metabolism,PCD and other physiological and biochemical processes of F.velutipes.Quantitative real-time PCR(q RT-PCR)further proved the molecular regulation mechanism of NP on the lignification.NP might promote lignin degradation by inducing the differential expression of GLG4 and delay the accumulation of lignin in F.velutipes by reducing the expression of SPAC16e8.04c,which ultimately delayed the accumulation of lignin.In addition,NP might maintain the homeostasis of ROS in F.velutipes by regulating the expression of msp2 and RBOHF and reduce the release of cytochrome C in mitochondria by decreasing the expression of cyc1,which ultimately delayed the PCD and the lignification of F.velutipes.