Abstract:[Background] Meloidogyne incognita is a common species of root-knot nematodes damaging plants in China, causing dramatic economic losses in greenhouse vegetable production. [Objective] To isolate and identify endophytic fungal strains against M. incognita and determine their biocontrol effects. [Methods] The fungal strains were isolated with the dilution-plate coating method and the strains with nematicidal activity were screened by the 24-well plate fluid model. The target strain was identified based on morphological properties and ITS gene sequence. The inhibitory effects of the strain fermentation liquid on the egg hatching and the survival of the second-stage juveniles of M. incognita were tested. Furthermore, a pot experiment was conducted to verify the biocontrol effect of the target strain on M. incognita infecting cucumber seedlings. [Results] A fungal strain JDC158 with strong nematicidal activity was screened out and identified as Sarocladium strictum. The fermentation liquid of strain JDC158 exhibited high toxicity to the eggs and second-stage juveniles of M. incognita, with a relative inhibition rate of 86.18% on egg hatching and causing the corrected mortality of 97.98% in second-stage juveniles after treatment for 96 h. The pot experiment showed that the biocontrol effects of the fermentation liquid of strain JDC158 at different concentrations all exceeded 43.93%, which were significantly higher than that of 5% avermectin EC. Moreover, the fermentation liquid of this strain promoted the growth of cucumber seedlings. [Conclusion] JDC158 could be considered as an endophytic fungal strain with biocontrol potential against M. incognita, providing a new microbial resource for the biocontrol of nematode diseases in plants.
