Transcriptional Changes of Salicylic Acid Dependent Signaling Pathways in Barley-Cochliobolus sativus Interaction

Spot blotch (SB), caused by the necrotrophic fungal pathogen Cochliobolus sativus, is an important disease of barley globally. Following transcriptional changes of salicylic acid (SA)-interacting/binding proteins during C. sativus infection may greatly advance understanding the defense crucial signaling pathways. In this study, changes of four known categories of defense; phosphorylation, ROS, PR proteins and nucleotide-binding sites encoded by genes involved in SA–mediated defense signaling networks were studied in compatible/incompatible barley-SB interactions. The functional categories showed significant differential accumulations when compared to the noninoculated controls, and they were primarily upregulated during fungal infection in the resistant cultivar compared with the susceptible one. However, SA profiling of resistant and susceptible cultivars indicated a reduction in its levels 72 hours post inoculation; therefore, we hypothesized that this signaling pathways may facilitate SB resistance. Furthermore, the expression of selected categories was induced earlier in resistant barley plants as in susceptible ones, supporting the hypothesis that a delayed defense response may occur in the C. sativus susceptible interaction.