Texture deterioration and cell wall metabolic dynamics in Chinese bayberry ( <i>Morella rubra</i> ) fruit during postharvest storage

Abstract Chinese bayberry (Morella rubra) fruit exhibits an extremely short shelf life due to rapid postharvest softening, yet the underlying cell wall metabolic mechanisms remain unclear. This study investigated the dynamics of cell wall components, cell wall-modifying enzyme activities, and related gene expression in Chinese bayberry fruits stored at 20 ℃ and 4 ℃. Low-temperature storage (4 ℃) significantly delayed softening, attenuated soluble pectin accumulation, and suppressed protopectin/hemicellulose degradation compared with 20 ℃ storage. These effects were associated with markedly reduced activities of polygalacturonase (PG), pectin methylesterase (PME), β-galactosidase (β-Gal), cellulase (CEL), and endo-β-1,4-mannanase (MAN). Transcriptome analysis identified six candidate genes (MrPG8, MrPME61, MrBGAL10, MrBGAL11, MrGH9B18, and MrMAN1) encoding key cell wall-modifying enzymes whose expression patterns closely paralleled their corresponding enzyme activities. These findings indicate that cell wall degradation is a major factor contributing to postharvest softening in Chinese bayberry. Low-temperature storage delays softening, at least partly, through transcriptional suppression of cell wall-modifying enzyme genes. This work provides a theoretical basis for developing precision low-temperature preservation strategies for bayberry and related perishable fleshy fruits.