Brachypodium distachyon as a model to understand resistance to wheat root diseases

The cultivation of wheat is an ever-increasing priority for the sustainability of food production worldwide, yet wheat is susceptible to various pathogens leading to considerable yield loss. Numerous studies have been performed to combine sources of resistance to these diseases without affecting yield. Most studies, however, are performed on visual infection phenotypes on aerial parts of plants, with considerable lack of disease studies on underground soil-borne diseases, like take-all and Fusarium root rot (FRR). Most wheat cultivars are considered susceptible to these diseases, with low differential in response. This factor combined with the high incidence of gene redundancy due to wheat's hexaploid genome, have resulted in a lack of knowledge on the genetic basis of resistance to root diseases of wheat. The purpose of this project was to further examine the model plant Brachypodium distachyon (Bd) to understand resistance to root diseases and identify potential resistance/susceptibility genes that play a significant role in response to FRR and take-all. The use of different Bd accessions lines, part of the recently re-sequenced Bd pangenome were used to examine responses to both diseases. A QTL analysis was performed in parent accessions of already developed Bd populations with promising resistance differential to FRR and Fusarium overall seedling death, demonstrating a novel source of resistance originating from chromosome 1 of Bd. A series of RNA-seq experiments were also conducted to characterize the response of susceptible line Bd21, to low concentrations of deoxynivalenol (DON) and reactive oxygen species (ROS). The results enabled definition of DON and DON-mediated ROS expression profiles within the plant in a non-toxic background. A characterisation of candidate genes involved in response to FRR and take-all was also performed, making use of Brachypodium T-DNA mutant lines, along with wheat Kronos TILLING mutant lines, establishing a model-to-crop system between Bd and wheat.