Transcriptome profiling reveals distinct gene activations in barley responding to scald and spot blotch

Scald (Rhynchosporium secalis; Rs) and spot blotch (Cochliobolus sativus; Cs) are important diseases of barley (Hordeum vulgare L.) worldwide. Similar mechanisms and gene transcripts are assumed to be involved in the barley defense response since both these pathogens are necrotrophic fungi. In the current study, the transcriptome in leaves of the same barley genotype WI2291 inoculated with Rs and Cs was compared at different times postinoculation. Comparison of data for barley Rs- and Cs- inoculated plants with mock-inoculated plants revealed gene expression changes that included basal defense transcripts and transcripts specific to the establishment of a necrotrophic interaction with associated fungi. During barley–pathogen interaction pathway, WI2291 activated a higher number of genes and pathways in response to Rs infection than in response to Cs invasion. However, families of genes encoding pectin-degrading enzymes, secondary metabolism enzymes, transporters and peptidases are expanded to cover Rs and Cs at an early stage following inoculation. Our results demonstrate differences in the pathways and activated genes of barely cv. WI291challenged by Rs and Cs, and that expression patterns of the same defense-associated genes were altered in adaptation to different pathogens. Our work provides new insights into the underlying mechanisms related to regulation of different pathways in response to fungal infection.