ARS | Publication request: GeneChip analyses identify specific non-host and R-gene resistance responses of barley to the septoria pathogens Mycosphaerella graminicola and Septoria passerinii

Submitted to: International Triticeae Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 19, 2006
Publication Date: August 28, 2006
Citation: Goodwin, S.B., Breeden, J.D., Stevens, J., Doerge, R.W. 2006. GeneChip analyses identify specific non-host and R-gene resistance responses of barley to the septoria pathogens Mycosphaerella graminicola and Septoria passerinii. [abstract] International Triticeae Symposium Proceedings. Paper No. 13.

Technical Abstract: Barley possesses specific resistance (R) genes against the speckled leaf blotch pathogen Septoria passerinii and is a non host for the Septoria tritici blotch pathogen of wheat, Mycosphaerella graminicola. The specific mechanisms of resistance against these pathogens, and whether they involve active host defense responses, are not known. The Affymetrix Barley GeneChip Array was used to test the hypothesis that non-host resistance of barley to M. graminicola is induced and differs from an R-gene response. Barley plants inoculated with i) a compatible isolate of S. passerinii (susceptible response) ii) an incompatible isolate of S. passerinii (R-gene response), and iii) an isolate of M. graminicola (non-host response), were collected at 0, 5, 12 and 24 hours after inoculation with two biological replications and water-inoculated controls at each time point. From 99 to 1,789 genes had significantly increased expression during the non-host resistance response relative to the water-inoculated controls among the four sampling times. Some of these genes are the same as those induced during R-gene resistance responses of barley to biotrophic pathogens and in other host species. However, the non-host responses were induced faster and involved many genes for cell wall strengthening and lignification that were not detected during the R-gene response. Changes in expression of representative genes identified with the GeneChip experiments were confirmed with real-time quantitative PCR. These analyses demonstrate that barley responds faster and by different mechanisms during non-host resistance to the wheat pathogen M. graminicola compared to the R-gene responses induced against the barley pathogen S. passerinii.