For enrichments at 72 hai associations to the infection with F. graminearum were restricted Inhibitors,Modulators,Libraries and, thus, were only possible if a GO term was also enriched also at 32 hai. The GSEA provided insides into defence mechanisms that were induced during incompatible interactions. At 32 hai an exclusive enrichment was observed for the terms lipoxygenase activity, Inhibitors,Modulators,Libraries oxyli pin biosynthetic process and lipid biosyn thetic process including genes, such as lipoxygenases, involved in the plant oxylipin metabolism. Additionally, lipoxygenases genes were also frequent in the term response to wounding. Putative cysteine rich proteins, such as thionins, were detected in the GO term pathogenesis. Phyto oxylipins comprising antimicrobial peptides and defence signalling molecules such as jasmonates, together with cysteine rich pathogenesis related genes indicate an induced anti fungal defence mechanism.
Plant serine protease inhibitors were enriched in the GO terms serine type endopeptidase inhibitor activity GO,0004867 and peptidase activity GO,0008233, Drug_discovery and unclear for the other terms. The detected GO terms chitin Inhibitors,Modulators,Libraries catabolic process and chitinase activ ity demonstrate the down regulation of genes which typically facilitate the breakdown of fungal cell walls. Chitinase genes have shown to exhibit an enhanced resistance against F. graminearum, in barley while in the grains of Emmer wheat, a pro genitor of bread wheat, a similar down regulation of chitinase genes was observed and discussed as a direct impact of F. graminearum signals. Finally, the term mycelium development comprises 10 F.
graminearum genes, belonging to a set of 69 Fusar ium genes which were previously found to be present on the Affymetrix Wheat GeneChipW. As these genes are putatively associated to the progression of the fungal myce lium, their enrichment amongst Inhibitors,Modulators,Libraries down regulated genes might reflect traces of an impaired fungal growth in the re sistant Dream cultivar. A comparison was performed between the cv. Dream Fusarium inoculated versus cv. Lynx Fusarium inocu lated expression data and the analogous expression data from the mock inoculation, in order to address expression changes in the resistant cv. Dream associated with the fungal attack. At 32 hai, the genes differentially expressed in cv. Dream could be separated into genes that were differentially expressed to higher levels or were represented the second class of genes enriched in the term response to wounding. Serine protease inhibitors as well as genes encoding serine proteases iden tified by the term serine type carboxypeptidase activity were enriched at both timepoints. These enriched terms represent an induced defence mechanism against pathogen released proteases which as virulence factors are secreted to modify host proteins.