Preharvest application of alginate oligosaccharides enhances the postharvest storage of kiwiberry by regulating cell wall degradation

The rapid degradation of the cell wall leads to firmness loss in fruit, resulting in a shorter shelf life and quality deterioration. Here, we evaluated the impact of preharvest foliar application of alginate oligosaccharides (AOS) on a perishable fruit kiwiberry ( Actinidia arguta ) over a 42 d storage period using physiological, molecular, and biochemical approaches. The selected plants were sprayed with the AOS solution 15 d before harvest, covering both the leaves and fruit surfaces. The preharvest AOS application significantly reduced decay incidence by about 60 %, maintained nearly twice the firmness, and 22 % less weight loss compared with control fruit after 42 d of storage. Transcriptome analysis reveals that AOS treatment downregulates the genes related to cell wall degradation. Moreover, biochemical analysis indicates that preharvest application suppressed the activation of cell wall degrading enzymes, reduced the solubilization of cell wall polysaccharides, and preserved their monosaccharide composition. These results reveal that preharvest application of AOS ensured the storability of kiwiberry by controlling cell wall degradation enzymes and gene expression. These findings highlight the significant potentiality of AOS preharvest treatments for delaying postharvest softening of kiwiberry.