Biocontrol efficacy of endophytic fungus, Acremonium sclerotigenum, against Meloidogyne incognita under in vitro and in vivo conditions

Biocontrol microorganisms are important tools for the control of root knot nematodes (Meloidogyne spp.). Endophytic fungi have shown great potential as biocontrol agents in such applications. We here isolated an endophytic fungus from tomato root galls infected with M. incognita and identified the isolate as Acremonium sclerotigenum based on morphology and the internal transcribed spacer sequence. The biocontrol potential of this fungus was evaluated both in vitro and in vivo. Specifically, in vitro analyses were conducted to determine the potential of A. sclerotigenum to increase Meloidogyne incognita juvenile (J2 stage) mortality and decrease M. incognita egg hatching rates. The results revealed that A. sclerotigenum culture filtrates caused high J2 mortality rates (up to 95.5%) and significantly inhibited egg hatching (by up to similar to 43%). Furthermore, eggs treated with the culture filtrate were disaggregated and could not develop into nematodes. An in vivo experiment showed that treatment of tomato plants with A. sclerotigenum suppressed root knot nematode populations and significantly reduced the galling index. Both A. sclerotigenum treatment and exposure to the nematicide abamectin had good control effects, with efficacy rates of 55.43% and 70.58%, respectively. In summary, the endophytic fungus A. sclerotigenum here showed excellent potential for biocontrol of M. incognita. Further studies should be conducted to identify the nematicidal compounds produced by this fungus and to establish the molecular mechanism of action associated with the observed biocontrol effects.