Effects Of Umbelliferone Treatment On Fruit Quality And Disease Resistance Of 'Xuxiang' Kiwifruit

Kiwifruit?Actinidia deliciosa.cv.Xuxiang?,as one of the main cultivar in Zhejiang Province,is easy to soften and extremely prone to storage diseases.Gray mold caused by Botrytis cinerea is a prevalent disease in kiwifruit after harvest.In this study,kiwifruit?A.deliciosa.cv.Xuxiang?were used as experimental material.In order to provide a theoretical basis for the storage and preservation mechanism of kiwifruit after harvest,the effects of 0.5mg/mL and 1.0 mg/mL umbelliferone treatment on fruit quality of kiwifruit under normal and low temperature storage as well as disease resistance to gray mold after inoculation with B cinerea were studied.Meanwhile,the effects of umbelliferone on the colony expansion and spore germination rate of Botrytis cinerea were also studied.The main results were as follows:1.0.5 mg/mL and 1.0 mg/mL umbelliferone treatment effectively reduced the rot rate of kiwifruit under normal temperature storage,and maintain fruit firmness and chlorophyll content in kiwifruit.Particularly,0.5 mg/mL umbelliferone treatment significantly inhibited the increase in soluble solid content?SSC?and soluble sugar and the decrease of titratable acid?TA?content in kiwifruit during storage.As compared to the control,the degradation of Vitamin C?Vc?content was delayed after treatment.The results indicated that the suitable concentration of umbelliferone treatment could maintain fruit quality under normal temperature storage and benefited to improve the high commercial value of kiwifruit.2.Umbelliferone treatment with two different concentrations significantly delayed the decline of hardness,soluble solid content?SSC?and soluble sugar in kiwifruit during low temperature storage.Particularly,0.5 mg/mL umbelliferone treatment could effectively alleviate the decrease of chlorophyll content and maintain the vitamin C?Vc?content in kiwifruit under low temperature storage.The results showed that the suitable concentration of umbelliferone could delay the ripening and senescence of kiwifruit under low temperature storage and maintain fruit quality well.3.Umbelliferone effectively inhibited spore germination and decrease colony diameter of B.cinerea.The expansion of the lesion area in kiwifruit inoculated with B.cinerea was also inhibited after umbelliferone treatment.While umbelliferone treatment was effectively enhancing the activity of defense-related enzymes,including chitinase?CHT?,?-1,3-glucanase?GLU?,phenylalanine ammonia lyase?PAL?,4-coumarate CoA ligase?4-CL?,peroxidase?POD?and polyphenol oxidase?PPO?in kiwifruit inoculated with B.cinerea.The content of resistant substances in treated kiwifruit were accumulated apparently,such as total phenolics,flavonoids,lignin and hydroxyproline-rich glycoprotein?HRGP?.Also,in the treated fruit,the lipoxygenase?LOX?activity was decreased,but the catalase?CAT?activity was stimulated.Particularly,the treatment with 0.5 mg/mL umbelliferone significantly increased the activities of ascorbate peroxidase?APX?activity and superoxide dismutase?SOD?during storage,while superoxide anion?O₂^-?production rate,hydrogen peroxide?H₂O₂?content and accumulation of malonaldehyde?MDA?content were inhibited effectively,which indicated that umbelliferone treatment could effectively control the incidence of gray mold in kiwifruit associated with the enhancement of disease resistance and antioxidant ability in kiwifruit during postharvest.