The identification of genes involved in the interaction between Triticum aestivum and Puccinia triticina

English: The aim of this study was to isolate a gene encoding a protein kinase that is involved in the specific recognition of the leaf rust fungus by wheat. It was determined that the susceptible Thatcher and resistant Thatcher/Lr34 plants reacted within 12 h.p.i to the presence of the leaf rust by activating the P-1,3- glucanase enzyme. A second increase in β-1,3-glucanase activity was found 24 h.p.i in the resistant plants and 54 h.p.i in the susceptible plants. The second increase occurred after an increase in β-1,3-glucanase protein levels, which occurred at 18 h.p.i in the resistant plants and 24 h.p.i in the susceptible plants. The initial activation could have been the result of the activation of already existing pl, 3-glucanase proteins within the cell, while the second was due to elevated protein levels. Thetime study was refined by concentrating on the very early events after infection. β-l,3-Glucanase activity increased within 12 hours in the resistant and at 15 h.p.i in the susceptible plants. The latter also showed an increase at 6 h.p.i. Thiscorrelated with increased β-1,3-glucanase polypeptide levels. In both the resistant and susceptible infected plants there was an increase in H202 levels within 6 hours that was accompanied by a simultaneous increase in peroxidase activity. possible communication event between infected and uninfected resistant Thatcher/Lr34 plants was investigated since the biochemical results suggested the occurrence of such an event. At this stage no concrete evidence supporting possible interplant communication could however be presented. DDRT-peRwas used to isolate potential differentially expressed protein kinase genes from the resistant plants during the first 18 h after infection. Nine cDNA sequences were cloned. The first five encoded a putative glutamine-dependent asparaginyl synthetase normally involved in nitrogen metabolism, an asparagine endopeptidase/legumain-like protease normally involved in the degradation of storage peptides, a mitochondrial 18S rDNA subunit, a high-molecular-weight glutenin subunit normally involved in storage of reserve metabolites, while the last clone did not show any similarity with any known gene, The DO RT-peR was repeated at more stringent conditions and another 30 putative protein kinase genes that were differentially expressed, were isolated, These cDNAs are currently being characterized.