Exogenous γ-GABA promotes lignin biosynthesis and antioxidant capacity to delay fruit softening and senescence of postharvest jujube fruit

Postharvest softening and rapid senescence severely limit the storage life and marketability of fresh jujube fruit. γ-Aminobutyric acid (GABA) has emerged as an effective postharvest preservative for horticultural crops; however, its role in regulating fruit firmness and senescence in postharvest fresh jujube fruit remains largely unclear. This study investigated the effects of exogenous γ-GABA on postharvest senescence and explored the potential mechanisms underlying firmness maintenance in ‘Dongzao’ fruit. Among the tested concentrations, 0.5 mM GABA showed the greatest efficacy, delaying red-turning until 20 days and reducing the decay incidence at 40 days to 17.06% of the control, while maintaining 1.12-fold higher firmness. Transcriptome analysis revealed that γ-GABA extensively reprogrammed phenylpropanoid and cell wall remodeling genes, strongly inducing POD‑related lignin biosynthetic genes while selectively suppressing major cell wall degradation genes. Correspondingly, γ‑GABA enhanced POD activity, which promoted lignin biosynthesis, consumed H 2 O 2 , and maintained a low O 2 •− production rate. It also significantly increased PAL, 4CL, and CAD activities but decreased total phenolics and flavonoids, indicating a redirection of phenylpropanoid flux toward lignin. Additionally, γ‑GABA delayed senescence by activating AsA‑GSH metabolism and antioxidant enzymes, thereby enhancing ROS scavenging. These findings indicate that γ-GABA delays postharvest softening and senescence by coordinating controlled lignification with ROS detoxification, thereby reinforcing cell wall integrity and maintaining redox homeostasis. This study provides new mechanistic insights into the contribution of controlled lignification to postharvest firmness maintenance and establishes GABA treatment as a promising means of improving the storage quality of fresh jujube fruit.