Abstract: In order to investigate how antioxidant enzymes inhibit the browning process of wampee fruit, we performed RNA sequencing using RNA-Seq technique on Clausena lansium fruit subjected to heat treatment (HT), low temperature conditioning (LTC) or no treatment (control) and then stored at 3 ℃ for 8 days. The results showed that compared with the control group, HT and LTC treatment could effectively postpone postharvest browning and water loss of wampee fruit, maintain higher activities of superoxide dismutase, peroxidase and catalase at the mid-to-late stage as well as higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity. The antioxidant activity of LTC-treated fruit began to significantly increase starting from the sixth day of storage. RNA-Seq results showed that totally 35 421 transcripts were collected; 1 631 and 5 404 differentially expressed genes (DEGs) were obtained on day 6 after HT and LTC treatment, respectively, compared with the control group. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG)?enrichment analysis?showed that these DEGs were mainly involved in plant hormone signal transduction, flavonoid biosynthesis, and phenylpropanoid biosynthesis, which may be related to antioxidant activity or browning resistance. From the DEGs, antioxidant gene groups IX, V and X were selected, whose expression could be induced by HT or LTC, thus delaying browning. These results may provide a theoretical basis for mining key antioxidant genes associated with wampee fruit browning.

Key words: Clausena lansium; antioxidant; transcriptome; differentially expressed genes