Abstract:

To clarify the efficacy and mechanism of action of Fusarium nematophilum NQ8GⅡ4 on Chinese wolfberry root rot，the inhibitory effect of F. nematophilum NQ8GⅡ4 on the mycelial growth of F. oxysporum f. sp. lycium barbarum was determined by the plate standoff method，and its effect on the control of chinese wolfberry root rot was determined by pot test，and the mechanism of action was analyzed by histochemical staining，the mechanism of action was analyzed by defense enzyme activity assay and histochemical staining. The results showed that pre-inoculation of strain NQ8GⅡ4 for 3 d significantly inhibited the growth of F. oxysporum mycelium with an inhibition rate of 70.07%. The inoculation of NQ8GⅡ4 strain with soil mixing method can significantly reduce the occurrence of Chinese wolfberry root rot in greenhouse，with 76.38% effectiveness，which is comparable to that of chemical carbendazim. Compared with the blank control，the agronomic traits of L. barbarum such as plant height，number of side branches，leaf width，stem diameter and root length increased by 37.61%，90.56%，52.50%，32.35% and 44.69% respectively after inoculation with NQ8GⅡ4 strain，which could significantly promote the growth of L. barbarum. Under F. oxysporum stress，leaf POD，SOD，PAL and CAT increased by 33.92%，65.64%，57.96% and 41.59%，respectively，while MDA content decreased significantly by 44.23% 21 days after inoculation with NQ8GⅡ4 compared to the control without NQ8GⅡ4. Inoculation of strain NQ8GⅡ4 promoted the growth of L. barbarum seedlings and stimulated the activity of defense enzymes in L. barbarum，and it stimulates the defense enzyme activity in L. barbarum and alleviates the membrane lipid peroxidation stress caused by F. oxysporum，thus improving the resistance of Chinese wolfberry root rot，which has good potential and application.

Key words: Chinese wolfberry, root rot, endophytic fungi, Fusarium nematophilum, biocontrol