Bacteria induce systemic acquired resistance (SAR) in barley

Abstract: We investigated the possibility to induce systemic acquired resistance (SAR) in barley in order to generate a monocotyledonous SAR pathosystem to test possible protection of cereals via SAR/priming. Infection of the first leaf of 4-week-old barley plants with either P. syringae pathovar japonica or Xanthomonas translucens significantly enhanced resistance in the systemic tissue against X. translucens. P. syringae growth was restricted in the infected leaf and caused numerous brown spots reminiscent of HR lesions. X. translucens seemed virulent, causing spreading lesions, severe yellowing and eventually death. We have performed microarray analyses of the local infected and systemic tissue to investigate which genes are induced and/or repressed during systemic resistance induction in barley. Results reveal that salicylic acid is dispensable, while interplay of other plant hormones is required for the induced resistance response.