Antifungal activity of wheat root exudate extracts on Gaeumannomyces graminis var. Tritici growth

Wheat (Triticum aestivum L.) is known for its ability to produce and release al- lelopathic compounds, which have potential for controlling weeds and diseases. Previous reports have shown the fungitoxic effects of allelochemicals present in wheat. Thus, these compounds can be exuded by roots to protect the tissues directly affected by Gaeumannomyces graminis var. tritici (Ggt) fungus that causes wheat take-all disease. The aim of this research was to evaluate in vitro the allelopathic ef- fect of root exudate extracts from four Chilean wheat cultivars on Ggt growth. Root exudates were released from wheat seedlings to a sterile culture medium without nutrients. Afterward, the exudates in the culture medium were separated by liquid- liquid extraction using ethyl acetate. Eight different concentrations were tested for each cultivar. The results showed that the degree to which the extracts strongly in- hibit the phytopathogen growth is highly dependent on both the concentration and the cultivar. The root extract of the Domo cultivar was significantly active against Ggt (MIC=0.36 mg mL -1 ). IC 50 and MIC values obtained for Dollinco and Domo root exudate extracts showed toxicity to Ggt. These findings may be considered in future studies related to the use of allelopathic potential as a selection factor in order to reduce the yield losses caused by various take-all diseases, as an alternative to chemical controls.