Pectic oligosaccharide inhibits postharvest decay and maintains kiwifruit quality by inducing host defense response

Pectin-derived bioactive molecules have been used as elicitors of defense response and other physiological processes in plants, including harvested fruit. In the present study, the postharvest use of a pectic oligosaccharide (POS) was investigated for its ability to inhibit blue mold (Penicillium expansum) and black rot (Alternaria alternata) in artificially-inoculated kiwifruit, as well as naturally-occurring infection. Results demonstrated that POS markedly inhibited blue mold and black rot, as well as natural infection in kiwifruit, relative to untreated, control fruit. POS upregulated the expression of defense-related and antioxidant enzyme genes, and corresponding enzyme activity, including chitinase, & beta;-1,3-glucanase and superoxide dismutase. Our data indicate that POS induces host defense responses in kiwifruit that increase resistance to postharvest decay pathogens. POStreated fruit also maintained a higher level of fruit firmness and total phenolic compounds than untreated, control fruit, and exhibited a reduced level of weight loss. Collectively, our study indicates that the use of POS may represent a potential strategy for prolonging the postharvest quality of kiwifruit.