Inducers of resistance reduce common bunt infection in wheat seedlings while differentially regulating defence-gene expression

In most incompatible plant host–parasite interactions, defence responses are triggered following activation of signalling pathways involving salicylic acid (SA) and jasmonic acid (JA). The effects of SA and methyl-jasmonate (MeJA) applied to Tilletia laevis Kühn inoculated wheat (Triticum aestivum L.) seedlings 1, 2, or 3 weeks following emergence, on infection and transcript levels of defence-related genes were investigated. Application of SA or MeJA coordinately activated transcripts of different groups of defence-related proteins and reduced common bunt infection. Three patterns of defence gene expression following the SA and MeJA treatments were observed: (1) Transcripts of Chi1, Chi3, Chi4, PR-1.1, PR-1.2, Glu1, and a lipase that were up-regulated in response to MeJA treatment, their expression potentiated by infection by T. laevis, and the highest transcript levels were associated with the 3-week seedling stage; (2) Transcripts of Glu2 responded almost exclusively to SA, were not potentiated by infection and the highest expression was observed in the 3-week seedling stage; (3) Transcripts of ns-LTP-1, ns-LTP-2, and Glu3 were up-regulated in response to both SA and MeJA, not potentiated by infection, and the highest transcript levels were observed in the 1-week seedling stage.