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In this study, caffeic acid-graft-chitosan/polylactic acid (CA-g-CS/PLA) packaging was shown to be effective in enhancing the storage stability of postharvest Agaricus bisporus, and its regulatory pathway was further elucidated. Results showed that expression levels of essential genes in the mitogen-activated protein kinase (MAPK) signaling pathway such as Sho1 , Ssk2 , Pbs2 , and Hog1 were upregulated in CA-g-CS/PLA packaging group. Furthermore, the accumulation of stress-resistant compounds was promoted by the packaging. Glycerol, γ-aminobutyric acid (GABA), proline, and glutamate were 2.6, 2, 1.4, and 2.3 times higher respectively than the PE group at the end of storage and their associated metabolic enzyme activities were promoted, similarly. Moreover, through correlation analysis, the pathway was shown to be related to the synthesis of stress-resistant compounds. These findings indicated that CA-g-CS/PLA packaging acted synergistically through both the synthesis of stress-resistant compounds and regulation of the MAPK signaling pathway to delay quality deterioration of postharvest A. bisporus. [Display omitted] • Caffeic acid grafted chitosan/polylactic acid (CA-g-CS/PLA) is applied for packaging. • CA-g-CS/PLA regulates the MAPK signaling pathway in A. bisporus. • CA-g-CS/PLA promotes the synthesis of stress-resistant compounds in A. bisporus. • CA-g-CS/PLA maintains the storage stability of postharvest A. bisporus. [ABSTRACT FROM AUTHOR]

• CA-g-CS/PLA regulates essential genes to maintain the quality of A. bisporus. • CA-g-CS/PLA retards cell membrane damage and elongation in A. bisporus. • CA-g-CS/PLA promotes the activation of MAPK signalling pathway in A. bisporus. In this study, the self-developed caffeic acid-grafted-chitosan/polylactic acid (CA-g-CS/PLA) film was applied to the preservation of Agaricus bisporus , and the potential mechanism of retarding its quality loss through regulation of essential genes was further explored. The results of transcriptome analysis showed that CA-g-CS/PLA packaging could regulate essential genes involved in membrane lipid metabolism and energy metabolism to delay the decrease in unsaturated fatty acids, energy loss and reactive oxygen species (ROS) accumulation by decreasing the respiration rate of A. bisporus. In addition, the expression of SHO1 and wis1 related to mitogen-activated protein kinase (MAPK) signalling in the CA-g-CS/PLA group of A. bisporus was increased, which indicated that the osmotic balance could be better maintained. Therefore, CA-g-CS/PLA packaging could improve the quality of postharvest A. bisporus by regulating the essential genes related to the pathway of membrane lipid metabolism, energy and ROS metabolism, and MAPK signalling transduction. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Caffeic acid grafted chitosan/polylactic acid (CA-g-CS/PLA) was used for packaging. • The Agaricus bisporus packaged by CA-g-CS/PLA showed more complete cell morphology. • CA-g-CS/PLA slowed the decline in lipid unsaturation and phospholipids. • The activities and expression of phospholipid degrading enzymes were inhibited. In this study, the film assembled by caffeic acid-grafted-chitosan/polylactic acid (CA-g-CS/PLA) was used for packaging postharvest Agaricus bisporus , and its effects on postharvest quality of Agaricus bisporus by regulating membrane lipid metabolism were investigated. The results showed that compared to traditional polyethylene packaging, the cell morphology of Agaricus bisporus packaged by CA-g-CS/PLA demonstrated a more complete structure due to its lower permeability, higher fluidity and stronger ability to maintain free water. Meanwhile, CA-g-CS/PLA packaging could effectively delay the decrease rate of unsaturation value and phospholipids of Agaricus bisporus during storage. In addition, the activities and expression levels of lipoxygenase (LOX), phospholipase C (PLC) and phospholipase D (PLD) in Agaricus bisporus packaged with CA-g-CS/PLA were inhibited, while those of glycerol-3-phosphate acyltransferase (GPAT) and sphingomyelin synthase (SMS) were promoted. Therefore, CA-g-CS/PLA packaging could enhance the postharvest quality of Agaricus bisporus by regulating membrane lipid metabolism, which has great application potential in the field of new intelligent packaging. [ABSTRACT FROM AUTHOR]

To clarify the effect of caffeic acid-grafted-chitosan/polylactic acid (CA-g-CS/PLA) packaging on the bacterial infestation and volatile flavor of postharvest Agaricus bisporus , electronic nose (E-nose) combined with gas chromatography-mass spectrometry (GC–MS) analysis was utilized to detect the volatile flavor. 16s rDNA sequencing technology was used to determine the species and changes of bacterial flora on the surface of Agaricus bisporus. The correlation between volatile flavor substances and bacterial communities was analyzed. The results showed that compared with polyethylene (PE) packaging, CA-g-CS/PLA packaging significantly delayed the loss of characteristic volatiles such as 1-octene-3-ol, 3-octanol, 3-octone and the ability to inhibit the growth of total bacteria count (TBC) was elevated by 12.6 % at 15 d of storage. Moreover, CA-g-CS/PLA packaging significantly reduced the abundance of spoilage bacteria such as Flavobacterium , Pedobacter and Pseudomonas compared to PE packaging and the sum of the three fell from 38 % to around 8 %. The correlation analysis showed that spoilage bacteria were significantly negatively correlated with 1-octene-3-ol and 3-octone and significantly positively correlated with spoil flavors such as benzaldehyde, indole and naphthalene. These results indicated that CA-g-CS/PLA packaging could delay the deterioration of the postharvest volatile flavor of Agaricus bisporus by inhibiting the abundance of specific spoilage bacteria. • CA-g-CS/PLA packaging could delay the loss of characteristic volatiles. • The abundance of Flavobacterium, Pedobacter and Pseudomonas was reduced. • The spoilage bacteria were negatively correlated with 1-octene-3-ol and 3-octone. • The undesirable flavors were positively correlated with main spoilage bacteria. [ABSTRACT FROM AUTHOR]