EVIDENCE FOR DIFFERENT SIGNALING PATHWAYS ACTIVATED BY INDUCERS OF ACQUIRED-RESISTANCE IN WHEAT

Acquired resistance (AR) of wheat (Triticum aestivum) to the powdery m ildew fungus Erysiphe graminis f. sp. tritici can be induced either by inoculation with the nonhost pathogen E. graminis f. sp, hordei or by treatment with chemical substances such as benzo(1,2,3)thiodiazole-7- carbothioic acid S-methyl ester (BTH). In the dicotyledonous plants to bacco and Arabidopsis, induction of AR by pathogens and BTH is accompa nied by the expression of a characteristic set of genes. Here we repor t that in wheat, BTH treatment failed to activate genes whose transcri pts accumulate after AR induction by nonhost pathogens, whereas BTH-in ducible genes were not activated by an appropriate pathogen inoculatio n. This suggests that at least two different pathways exist for the in duction of AR in monocots.