Pathogen-responsive wheat PR4 genes are induced by plant activators of systemic acquired resistance and wounding

The expression of Triticum aestivum PR4 genes is regulated in response to infection with F. culmorum, a widespread soil-borne pathogen that causes severe damages in crops through foot rot. The induction of PR4 transcripts in wheat coleoptils and roots is correlated with the expression of the corresponding proteins that are expressed only in the infected tissues. Wheat PR4 genes and proteins are also inducible upon treatments with systemic acquired resistance (SAR) chemical inducers such as salicylic acid (SA), benzo(1,2,3)thiodiazole-7-carbothioic acid S-methyl ester (BTH) and methyl jasmonate (MeJA) indicating that activation of PR4 genes follows both SA- and JA-dependent defense response pathways. Moreover, wheat PR4 genes are induced in response to wounding in young shoots and roots as well as in mature leaves suggesting that they can be considered useful markers of plant defense response, although SAR has not been conclusively demonstrated in wheat. Wheat PR1 and PR5 genes used for comparison did not respond to either SAR activators or pathogen attack.