Insights into Nematode Biocontrol Potential Through Biological and Proteomics Analysis of the Fungus Trichoderma viride

Nematophagous fungi such as Trichoderma viride show promising potential in the biological control of plant-parasitic nematodes. Furthermore, Meloidogyne spp., root-knot nematodes, has a great impact on the economy. The current study aimed to evaluate the parasitism ability of this fungus and to predict possible mechanisms involved in controlling the root-knot nematode, Meloidogyne javanica. In vitro bio-assays of direct parasitism, SEM observation, pot experiment testing the effect of soil treatment by T. viride, and isobaric tag for relative and absolute quantitation (iTRAQ) methodology were employed to characterize the biological and molecular features of this fungus. The high nematicidal activity was observed with the presence of Trichoderma species. The SEM observation of nematode parasitized juvenile suggests the production of lytic enzymes degrading the cell wall and penetrating fungal hyphae into M. javanica juveniles. The soil treatment by T. viride showed a significant boost of the tomato plant growth, a decrease of the root-knot nematode development in terms of galls number, gall index and multiplication rate and induction of defense responses by activating several ROS enzymes. A total of 1344 unique proteins were identified from the T. viride mycelium. These proteins were mainly related to signaling stress response, bio-energy, metabolism and protein synthesis and degradation. Our results provide a comprehensive dataset of several proteins involved in the biocontrol mechanisms of T. viride. The combination of several mechanisms allowed this filamentous fungus to be a successful candidate in controlling sustainably the root-knot nematodes, in particular, in Mediterranean ecosystems.