Study On The Mechanism Of Chitosan And Antagonistic Yeast Against Postharvest Diseases Of Kiwifruit

Kiwifruit is rich in nutrients,fragrant and refreshing,and the sales in fruits are among the best,bringing great economic benefits to society.However,the economic chain is seriously damaged because it is often plagued by postharvest decay.Aiming at preservation and postharvest decay of kiwifruit,traditional chemical methods have disadvantages such as high residue,and people's demands for quality of life have increased year by year,and the country's advocacy for environmental protection has become stronger,therefore,looking for eco-friendly bactericide alternatives has become a new research hotspot.In this study,the biological control ability and molecular mechanisms of chitosan and two yeast antagonistic strains isolated from fruit surface against postharvest gray mold(Botrytis cinerea)and blue mold(Penicillium expansum)in “Hong Yang” kiwifruit were investigated,and then,the effects of two control methods on storage quality,decay incidence,physiological and biochemical characteristics,resistance-related enzyme activity and expression of resistance-related gene expression of kiwifruit were further studied.The findings are as follows:1.Chitosan had no significant effect on soluble solid content,titratable acid,but extremely exhibited beneficial effects on hardness,it also significantly reduced the natural disease incidence in 4?,particularly.Compared with the control,chitosan significantly reduced the incidence of gray mold and blue mold in kiwifruit.Chitosan improved the enzyme activity of catalase,superoxide dismutase,ascorbate peroxidase,and the content of total phenol in kiwifruit,in addition,promoted the expression levels of corresponding resistance-encoding genes to varying degrees,inducing the defense stress system of kiwifruit.2.Both C.oleophila and D.nepalensis significantly inhibited the incidence of gray mold and blue mold in kiwifruit,and lesion diameter was significantly lower compared with the control.Moreover,enhanced the contents of total phenol and lignin,as well as increased expression levels of resistance genes(APX,CAT,SOD,GR)in kiwifruit.C.oleophila had faster growth and reproduction rate compared with D.nepalensis in kiwifruit.These findings indicated that both chitosan and two yeast strains showed good preservation and antagonistic effects on kiwifruits.These results provided a viable approach for the development of green biological control technology in the application of post-harvest disease prevention in fruits.