Background: Fresh-cut processing promotes enzymatic browning of fresh fruits and vegetables, which negatively affects the appearance of products and impacts their nutrition. We used the RNA-Seq technique to analyze the transcriptomic changes occurring during the browning of fresh-cut eggplant (Solanum melongena L.) fruit samples from a browning-sensitive cultivar and a browning-resistant cultivar to investigate the genes and molecular mechanisms involved in browning. Results: A total of 111.55 GB of high-quality reads were generated, the genomes of each sample were compared, and 83.50%–95.14% of the data was mapped to the eggplant reference genome. Furthermore, a total of 19631 differentially expressed genes were identified, among which 12 genes and two WRKY transcription factors were identified as potentially involved in enzymatic browning in fresh-cut eggplant fruit. Moreover, the 14 differentially expressed genes associated with browning were verified using qRT-PCR. Conclusions: Several genes associated with phenolic oxidation, phenylpropanoid biosynthesis, and flavonoid biosynthesis were found to be differentially regulated between the eggplant cultivars with different browning sensitivities. This work is of great theoretical significance, as it provides a basis for future molecular studies and improvement of eggplants, and lays a theoretical foundation for the development of browning-resistant fresh-cut fruits and vegetables.

In this study, SmWRKY53 gene was selected from the data of high temperture transcriptome and gene expression detection of "Tewangda" seedlings. It was then cloned, bioinformatics and preliminary expression analyzed. The results showed that the open reading frame of SmWRKY53 gene was 1 083 bp, encoding 360 amino acids. The 138-144 amino acids contain a typical "WRKYGQK" conserved domain, and the zinc finger structure is C2HC type, belonging to the Group Ⅲ subfamily. The homology comparison and phylogenetic tree analysis showed that SmWRKY53 was closely related to StWRKY53 of potato (Solanum tuberosum), and the homology is 91.41%. Bioinformatics prediction showed that SmWRKY53 was a basic and unstable hydrophilic protein with no signal peptide and transmembrane domain. The ratio of random coil in the secondary structure of protein was the highest, 63.89%. There was amino acid disorder structural regions in the SmWRKY53 protein. Subcellular localization prediction indicated that the protein was most likely located in the nucleus. Quantitative Real-time PCR results showed that the relative expression levels of SmWRKY53 was the highest in mature stem and the lowest in flesh. The expression of SmWRKY53 in roots, stems and leaves of eggplant seedlings first increased and then decreased, and reached the peak at 3 h under high temperature stress. This study provides the reference for further exploring the function of SmWRKY53 gene.

Objective ： Fresh-cut fruits and vegetables is an emerging type of fruits and vegetables processing products for consumers to eat immediately or for the catering industry. Enzymatic browning is one of the crucial problems compromising the flavor and texture of fresh-cut fruit and vegetables. Eggplant is a common vegetable, which is favored by consumers. Accordingly, we used an untargeted metabolomics approach based on liquid chromatography-mass spectrometry (LC-MS) to explore the browning mechanism in peeled eggplant ( Solanum melongena L . ). Results: Metabolomics revealed several hundred differential metabolites, including lipids, phenols, sugars and fatty acids. The content of these metabolites changed dynamically as the peeled time increased. The content of polyphenols, especially chlorogenic acid, increased significantly, suggesting that the main substrate for enzymatic browning in eggplant is chlorogenic acid. Furthermore, all the differential metabolite were mapped to KEGG pathway, revealing significant differences in linoleic acid metabolism, tyrosine metabolism，glutathione metabolism, pentose phosphate pathway, tropane, piperidine and pyridine alkaloid biosynthesis, phenylpropanol metabolism and glycosylphosphatidylinositol(GPI)-anchor biosynthesis over time. Therefore, we speculate that some metabolic pathways that are closely connected with respiration, glycolysis, ATP synthesis, and phenolic synthesi are disturbed after peeling, under the action of enzymes, eventually leading to browning.