A transgenic fungi substitutes chemical fungicides

Modern agriculture highly depends on the use of chemical agents to fight plant diseases. People nowadays are more and more concerned about the application of chemical fungicides to plants used for food and feed industry. Since about two decades biocontrol fungi from the genus Trichoderma are used as a biological alternative to control phytopathogenic fungi. Trichoderma is known to be highly interactive in root, soil and foliar environment and produces several antibiotics and fungal cell wall degrading enzymes. Furthermore beneficial effects on growth and development of Trichoderma protected plants have been reported. However, the Trichoderma based biocontrol formulations still cannot compete with chemical fungicides due to insufficient efficacy. Molecular approaches to improve mycoparasitic ability by overexpressing biocontrol related genes were of limited success as the transgenic strains exhibited no or only marginal benefits if tested in planta. An alternative way of biocontrol is followed by Talaromyces flavus, known to suppress Verticillium wilt by glucose oxidase production. In a preliminary study we combined the beneficial effects of these two fungi by heterologously expressing glucose oxidase in T. atroviride P1. In addition to the improved mycoparasitic activity of this recombinant strain we also got promising results concerning the external activation of plant defense. However, at this stage of investigations we used T. atroviride P1, a model organism but not a commercially applied biocontrol fungus. To get a marketable product we plane to transfer our system into T. harzianum 1295-22 (T-22), a commercially used, highly rhizosphere competent biocontrol agent. Furthermore, promoters of new biocontrol related gene for heterologous expression bioactive molecules in T. harzianum (T22) will be isolated. Finally we intend to heterologously express the pectate lyase A of Fusarium solani in T. harzianum T22 to cause an activation of a broad spectrum of plant defense related genes. Summarizing we hypothesize that improving the complex network of Trichoderma endogenous biocontrol ability and transgenic introduced plant defense activating enzymes in a highly rhizosphere competent Trichoderma strain will led to marketable products useful for a long term and high efficient protection of various economic plants against their respective pathogens.