Positive effects of yeast soluble cell wall polysaccharide on fruit postharvest control through resistance response.

Yeast-derived cell wall polysaccharides possess numerous biological activities, but their application in postharvest preservation is rarely reported. The aim of this research was to investigate the effects of Kluyveromyces marxianus soluble cell wall polysaccharide (SCWP) on preventing the infection of Penicillium expansum in pear fruit. The results showed that K. marxianus SCWP treatment could significantly improve the resistance of pear fruit to P. expansum, with respect to Saccharomyces cerevisiae-derived SCWP. Composition of both SCWPs was mannan with the main chains consisting of a → 6)-α-D-Manp-(1 → unit and the branch structure formed by → 2)-α-D-Manp-(1 except that K. marxianus SCWP took on a shorter side chain and a rougher surface than S. cerevisiae SCWP. In addition, mechanisms of K. marxianus SCWP on stimulating resistance response were associated with the apparent oxidative burst, increased gene expression and enzyme activity of antioxidant and defense systems in pear fruit. Our findings suggest that K. marxianus SCWP can be used as an innovative and promising candidate for preventing postharvest fungal decay and extending fruit shelf life.