An emerging crop, intermediate wheatgrass (IWG) is resistant to the natural occurrence of most important cereal diseases and is currently under domestication to improve its yield. An IWG population consisting of two parental lines and 154 individual F1 progenies were inoculated with F. graminearum spores in a field setting to check their performance against Fusarium head blight (FHB) over two consecutive years. The higher humidity in 2022 lead to higher FHB severity and incidence, and higher DON (deoxynivalenol) mycotoxin accumulation than in 2021. DON was mostly restricted to the chaff in 2021, whereas in 2022, DON was found in the grain as well. Considering all the FHB aspects checked in this experiment, four IWG progeny individuals (plants: P-17, P-43, P-107, and P-139) were found to consistently perform better than the parental lines and the other progeny individuals during both years.
The second part of this thesis analyzed the influence of F. graminearum on the mycobiome of IWG spikelet and flag leaf samples from two different locations, Winnipeg and Carman, MB. A total 372 IWG samples (half of which were inoculated with F. graminearum [Winnipeg] and the other half, not [Carman]) were used for fungal community profiling via ITS amplicon sequencing using PacBio technology. There were significant differences in the fungal community among the IWG spike samples from Winnipeg and Carman. As expected, F. graminearum dominated IWG spike mycobiomes at the inoculated Winnipeg site, whereas in Carman, Alternaria dominated. Also, the presence of F. graminearum seemed to influence the broader spike mycobiome and the presence of beneficial fungi was less where F. graminearum dominated. The mycobiome data also revealed that the pathogenic fungi Alternaria, Nigrospora, Septoriella, Stemphylium, Claviceps, Bipolaris, and Drechslera can become potential threats to IWG in the future.
The last part of this thesis sheds light on the interaction between F. graminearum and another agriculturally important fungus, Claviceps purpurea. In planta interactions showed that C. purpurea can negatively affect infection by F. graminearum only if C. purpurea was introduced first into the plant site, but further investigation of this is necessary for confirmation.