Investigation of the antifungal activity of lycene (Usnea longissima) extracts against fusarium graminearum isolats

The methods developed to protect plants from diseases in agriculture are largely based on the use of chemical pesticides. The use of fungicides and fumigants, which are among chemical pesticides, has serious effects on soil biota and has negative effects on the environment and consumers. These methods are not economically viable in the long term, as they harm the environment and cause atmospheric pollution. For this purpose, biocontrol agents are used specifically for control of error in plants. In this thesis project, the antifungal activity of U. longissima extracts on F. graminearum PH-1 and H11 isolates as allelopathic agents was determined and the changes caused by the antifungal extracts in F. graminearum isolates were determined using real-time polymerase chain reaction (qPCR) of the Mst20, CAT and tri5 genes. has been examined. According to the phentotypical analysis results, F. graminearum PH-1 isolate was determined to be the most affected isolate compared to H11 isolate against lichen extracts. U. longissima methanol extractor was found to have a more pronounced antifungal effect than acetone extractant. It was observed that the antifungal inhibition zone diameter increased proportionally due to the increase in the concentration of the U. longissima extracts used in the experiment. A more pronounced antifungal activity was observed in U. longissima methanol extract (30 ± 0) with a concentration of 50mg/ml compared to acetone extract of the same concentration (26.5 ± 2.121). While the positive control group tetraconzole was found to have a significant antifungal effect against the isolates tested, negative control group showed no antifungal activity against DMSO and acetone F. graminearum isolates. According to the gene expression analysis results, when the expression levels of mst20 associated with apoptosis and CAT genes responsible for oxidative stress were statistically compared with the control group, a significant increase was found in both isolates. When the expression levels of the tri5 gene responsible for mycotoxin production were compared statistically with the control group, a significant decrease was observed in both F. gramiearum isolates compared to the control. Considering the limited studies of lichens based on antifungal effects in the literature review, the subject of examining the antifungal activity of lichen (U. longissima) extracts against F. graminearum isolates is important in terms of being unique and contributing to research as a biocontrol agent.