Effects Of Melatonin Treatment On Ripening And Senescence Of Postharvest Mango

Mango(Mangifera indica L.)is a typical climacteric fruit.The postharvested fruit can reach maturity within 6-14 days when stored at ambient condition,leading to a relatively short shelf-life and restricted product trade.Melatonin(N-acetyl-5-methox ytryptamine)is a kind of bioactive molecule widely existing in plant,which has many biological functions.In the plant kingdom,melatonin was early identified as a robust quencher of reactive oxygen species(ROS)and an activator of the antioxidant system,and was subsequently confirmed to be a phytohormone-like signal molecule that has participated in regulation of multiple physiological processes.In order to explore the mechanism of melatonin on postharvest mango preservation,the ripening quality and senescence characteristics were evaluated during the process of room temperature storage.In this study,“Guifei” mango was used as experimental material to study the effects of melatonin treatment on mango quality,softening characteristics and plant hormone metabolism.The specific research results are as follows:1.Melatonin(0.5 mm,immersion for 1 h)can effectively delay the change of ripening parameters in “Guifei” mango,including firmness,pulp color,soluble solid content(SSC),totol titratable acidity(TTA)and changes of nutritional quality such as ?-carotene,ascorbic acid(As A),total phenol,flavonoids et al,which shows a certain effect on delaying ripening process on mango fruit,and has a positive impact on the maintenance of mature quality.2.Melatonin treatment inhibited the activities of pectin modifying enzymes(including polygalacturonase(PG),?-Galactosidase(?-Gal)and pectinmethylesterase(PME))and endo-1,4-?-D-glucanohydrolase(EGase)significantly,and the increase of these hydrolase activities would accelerate the process of cell wall hydrolysis,leading to the increase of pectin polysaccharide(water-soluble pectin and cyclohexanediamine tetraacetic acid(CDTA)soluble pectin)and hemicellulose polysaccharide dissolution and depolymerization,eventually lead to accelerated degradation of cell wall.3.Melatonin treatment can delay the automatic catalytic reaction caused by ethylene release and related metabolism during fruit ripening and softening.Delay the accumulation of abscisic acid(ABA)the important senescence-related plant regulator,and inhibit a key ABA biosynthetic enzyme(NCED)activity increased.