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Fruit firmness is an important trait of postharvest blueberry, and ethanol vapor treatment has been shown to can retard blueberry softening by inhibiting the degradation of cell wall polysaccharides in our previous work. However, fruit softening is a complex process regulated by many factors. Here, the regulation mechanism of ethanol mediated delaying blueberry softening at the levels of mRNA and protein were explored with integrated transcriptomics-proteomics analysis. Results revealed that, 9158 differentially expressed genes (DEGs) and 1223 differentially expressed proteins (DEPs) were identified in the ethanol vapor-treated blueberry (E20) compared with the control (C20) at the 20th day of cold storage, 351 correlation molecules (DEG/DEP) were obtained through correlation analysis. Ethanol treatment reduced the overall metabolism level of blueberry, downregulated the gene expression of polygalacturonase, glucan-1,3- β -glucosidase and endoglucanase in carbohydrate metabolism pathway, and slowed down the degradation of cell wall polysaccharides such as pectin and cellulose; downregulated the gene expression of ACC oxidase, the key enzyme for ethylene synthesis, reduced the production of ethylene, reducing the ripening and softening effect of ethylene on the fruit, and then delayed the softening process of blueberry fruit. Collectively, ethanol vapor is a promising technology for retarding the softening of fruit and vegetables. • Ethanol vapor-treated blueberries maintained a higher level in firmness. • Ethanol vapor treatment regulated the carbohydrate metabolism of blueberry. • Ethanol vapor treatment regulated the carbon fixation in photosynthetic organisms. • Ethanol vapor treatment regulated ethylene synthesis. • Ethanol regulated MAPK signaling pathway-plant and plant-pathogen interaction. [ABSTRACT FROM AUTHOR]

LAB are mostly used microorganisms for traditional fermented foods, e.g. Chinese northeast sauerkraut. However, the interactions between these strains are little known in mixed culture. This study aimed to explore the interaction between Leu. mesenteroides and L. plantarum based on metabolomics and transcriptomics during single- and mix-cultured fermentation of Chinese northeast sauerkraut. Metabolomics analysis revealed that the mixed culture showed different metabolite profiles in comparison with single culture. Higher levels of 4-vinylphenol (4.51%), 2,6-diaminopimelic acid (4.47%), ethyl dodecanoate (5.53%) were observed in mix-cultured samples than that with Leu. mesenteroides. In addition, the levels of 4-isopropylbenzoic acid (3.54%), 2,3-butanediol (7.23%), 1-octadecene (5.15%), ethyl dodecanoate (5.53%) were higher than that with L. plantarum. The most influenced pathway was carbohydrate metabolism, which was mostly related to 116 genes considered as DEGs in C_30 versus D_30 groups (CD), according to transcriptomics analysis. Additionally, 69 genes were considered as significantly DEGs in C_30 versus A_30 groups (CA) which were considerably mapped to amino acid metabolism. These results provided integrated views into the adaptive responses of the two strains to mix-cultured fermentation, which was useful for the rational development of mixed cultures in sauerkraut industry. • Sauerkraut was fermented by single and mixed cultures. • Metabolomic and transcriptomic elucidated interaction between Leu and Lpl. • Mix-cultured fermentation significantly affected the gene expression of Leu and Lpl. • Leu. mesenteroides mainly stimulated carbohydrates metabolism of L. plantarum. • Genes involved in amino acid metabolism of Leu were significantly upregulated by Lpl. [ABSTRACT FROM AUTHOR]