In fact, two transcript sequences homologous to the wheat thionin gene THI1. 1 were differentially expressed in the cv. Dream after both treatments, but not in the cv. Lynx. Thionins have a general antimicrobial activity against early conidial germination. In addition, a highly inducible expression was observed in the case of the Arabidopsis thionin Thi2. 1 after both fungal infections as well Inhibitors,Modulators,Libraries as MeJA treatment leading to an enhanced resist ance to F. oxysporum. Peptidase inhibitors of the defensin family make up the third class of continual up regulated AMPs, represented by homologues of the wheat gene Tad1 and the defen sin precursor PRPI 7 from durum wheat.
While the antimicrobial activity of defensins requires typically complex synergis tic interactions with other AMPs, their promoters are potentially interesting candidates for the targeted and tissue specific expression of PR and R genes, par ticularly for the protection against F. graminearum in Inhibitors,Modulators,Libraries cereal grains. An induction by jasmonates was reported for most of the defensin genes and some of the putative antifungal defensins are reported to be markers for the presence of JA and ET dependent defence signalling pathways. Indeed, indications for an active ET signalling were found in the FHB attacked cv. Dream transcriptome as well. The majority of up regulated cysteine rich AMPs in cv. Dream have shown expression values that were inde pendent Cilengitide of the treatment, but were lower or absent in the susceptible cv. Lynx. It is likely that the majority of these peptides act syn ergistically in a generalized non specific defence provid ing a basal protection.
AMPs transcribed at a constant level are known key components of an immediate de fence against invading pathogens, and many pro teins that are Inhibitors,Modulators,Libraries pathogen inducible, for example, in leaves were found to be constitutively present in storage tis sues, such as seed. Moreover, it is generally assumed that genes involved in the quantitative FHB resistance of adapted European wheat cultivars represent such a de fence mechanism. Nonetheless, AMPs can also be part of an induced plant defence. In FHB treated cv. Dream spikes only nsLTP genes were up regulated in response to the disease. Among these Ta. 7843. 1. S1 a at seems to be an interesting resistance candidate, as the gene combines a general high antifungal property with considerable fold change expression ratios at both time points.
Moreover, the putative defensin gene PRPI 7 might be a relevant finding as well due to Inhibitors,Modulators,Libraries its possible utilization in a resistant strategy aiming at over expressions of pathogen inducible promoters to directly target the infection sites or the most vulnerable tissues. Such an approach becomes even more inter esting with the recent observation that the biotrophic life form of F. graminearum persists in all colonized tissues.