Transcriptome revealed the wound-healing process of broccoli stem during SAS based on the hub of NADPH

Abstract

Wound healing is a crucial metabolic process that occurs in fruit and vegetables within a short time after harvest, especially in cut-harvest ones. To reveal wound healing mechanisms in cut-harvest broccoli stems during the self-adaptive stage (SAS, 12 h after harvest), tissue samples from the stems at the incision were analyzed at the transcriptome level. With the extension of time, the expression levels of six differentially expressed genes (DEGs) in the pentose phosphate pathway (PPP) significantly increased in the stems after cut-harvest. Among the genes, the expression levels of PGLS and PGD, which are directly involved in nicotinamide adenine dinucleotide phosphate (NADPH) generation, were 2.62 and 5.82 times higher in the 12 h vs 0 h comparison group, respectively. The shikimate and phenylpropanoid pathways were significantly activated in the broccoli stems during SAS. Genes involved in NADPH degradation through the aforementioned two pathways, including DHQ-SDH1 (106323466), aroC1 (106295042), and PAL3 (106300639), were significantly upregulated. These findings certified that wound healing of cut-harvest broccoli stems was promoted by enhancing NADPH levels. Interestingly, glycolysis (EMP) was a non-significant change during SAS after cut-harvest that contributed to maintaining organic matter by suppressing respiration and acclimatizing the postharvest broccoli to become an independent unit. These results indicate that the focus should be on NADPH levels for promoting wound healing of fruit and vegetables during storage.