The remaining gene classes transcription or signalling genes, miscellaneous defence related genes and hormone metab olism have been made for the convenience of discussion. Indications for a Jasmonate dependent enhancement of FHB resistance in wheat Indications for the presence of a JA signalling were found in the cv. Dream transcriptome after FHB infection by using GSEA testing. The GO terms lipoxygenase activity, oxylipin biosynthetic process and lipid biosynthetic process associated to the oxylipin metabolism were exclusively enriched in the early 32 hai gene expression data indicating that the chloroplastic 13 LOX branch was induced upon FHB infection. Hormone like compounds such as JA and methyl jasmonate, as well as 13 HPL derived C6 aldehydes, are characteristic products of this pathway.
Some oxylipins generated by the 13 LOX pathway, for example thaumatin like proteins and phytoalexins, exhibit antimicrobial activ ities by impairing fungal mycelial growth and spore germin ation. Other oxylipins, such as JA and MeJA are well known to serve important roles in plant defence signalling by mediating Inhibitors,Modulators,Libraries the induction of the expression of some PR genes. Moreover, as 13 LOX oxylipins Inhibitors,Modulators,Libraries are substantially produced from cuticle or cell membrane associated fatty acids released during the fungal degradation of plant cell walls, they also act as elicitors involved in pathogen recognition. Threeputative Lox genes were FHB re sponsive induced at 32 hai. The tran script Ta. 13650. 1. A1 at was found to be a homologue of the maize gene ZmLOX6 which is a novel chloroplast localized Lox gene described as uniquely regulated by phytohormones and pathogen infection.
The two transcripts Ta. 1967. 2. A1 x at and TaAffx. 104812. 1. S1 s at showed significant similarity to the barley gene Hordeum vulgare methyljasmonate inducible lipoxygenase 2. Therefore, both transcripts might encode for one or two putative methyljasmonate inducible chloroplastic Brefeldin_A 13 Lox genes. It was shown that jasmonates Inhibitors,Modulators,Libraries regulate their synthe sis via positive feedback control by inducing the transcrip tion of biosynthesis genes such as Lox2. It is remarkable that both transcripts were also already induced 24 h after F. graminearum inoculation in the resistant spring wheat cv. Sumai 3. Five Lox genes were up regulated after both treat ments and, in contrast to the solely FHB dependent induced Lox genes, three of them were also expressed at 72 hai.
Here, except for the transcript Ta. 1967. 1. S1 x at, none of the genes could be assigned to a JA mediated defence based on sequence similarities to published genes. Ta. 1967. 1. S1 x at, however, Inhibitors,Modulators,Libraries a homologue of a barley gene Lox2 involved in different stress responses, was also shown to be active in cv. Sumai 3 upon F. grami nearum infection. In summary, putative functions regarding defence re sponse mediation were assigned to genes showing FHB associated expression alterations.