Research On Antioxidant Activity Of Curcumin And Its Inhibitory Effect On Pathogens Of Kiwi Fruit

Curcumin,as a new antioxidant,has been widely used in fruit and vegetable preservation,food preservative,anti-inflammatory and so on.The fruits and vegetables are most vulnerable to the fungal pathogens after picking,Botrytis cinerea and Phomopsis which are the most common fungal disease.In this paper,four different concentrations of curcumin were used to handle the inhibition of curcumin on the growth of mycelium of two pathogenic fungi in vitro and in vivo,inhibition of curcumin on spore germination of pathogenic fungi.The activities of reactive oxygen species(ROS),malondialdehyde(MDA)and the activities of peroxidase(POD),catalase(CAT),glutathione peroxidase(GSH-Px)and superoxide dismutase(SOD)in the pathogen after curcumin treatment were studied.Real time quantitative PCR was used to detect the expression level of pathogenic genes and antioxidant enzyme genes in curcumin treated mycelium.The molecular mechanism of curcumin inhibition on pathogenic bacteria was analyzed from the molecular level.The experimental results show that,the incidence rate and the diameter of disease spot of kiwifruit treated with curcumin decreased significantly after inoculation of pathogen spore fluid.Curcumin inhibited the growth of mycelia and pathogen spores and germination of pathogenic fungi in vitro.In a certain range,with the increase of curcumin concentration,the inhibitory effect is more obvious.The accumulative ROS level of mycelium treated with curcumin decreased significantly,and the MDA content of mycelium also decreased.In addition,in real time quantitative PCR,the expression levels of Bmp3 and Sak1 which in the MAPK signaling pathway of Botrytis cinerea mycelium treated by curcumin were lower than those in the control group.The expression levels of two subunit of NADPH encoding genes 10823,6200 and SOD1 which is SOD encoding gene were higher than those of control group.It is concluded that curcumin inhibits the growth of pathogenic fungi by activating the MAPK signaling pathway of pathogenic fungi and down-regulating the pathogenicity related genes so that hyphal growth and spore germination can be controlled to a certain extent.