Systemic acquired resistance and induced systemic resistance against foliar diseases of Agrostis stolonifera and Nicotiana benthamiana

Systemic acquired resistance (SAR) was activated by benzothiadiazole (BTH) and induced systemic resistance (ISR) was activated by (2R,3R)-butanediol or PC1, a new isoparaffin compound developed by Petro-Canada, against anthracnose caused by Colletotrichum orbiculare in Nicotiana benthamiana. BTH, (2R,3R)-butanediol and PC1 reduced the number of lesions per leaf area of C. orbiculare by 98%, 77% and 81%, respectively. Foliar application of BTH also induced expression of pathogenesis-related (PR) genes, NbPR-1a, NbPR-3Q and acidic NbPR-5, and soil application of (2R,3R)-butanediol or PC1 primed expression of NbPRb-1b, basic NbPR-2 and NbPR-5dB. BTH also activated resistance against dollar spot caused by Sclerotinia homoeocarpa in Agrostis stolonifera , reducing the percentage of diseased leaves by 50%, but BTH did not activate resistance against diseases caused by Microdochium nivale ,or Rhizoctonia solani. However, application of either (2R,3R)-butanediol or PC1 reduced the area diseased leaves by 20 to 40% for M. nivale, R. solani or S. homoeocarpa. In A. stolonifera, expression of the jasmonate-related genes, AsAOS1 and AsOPR4, and the PR gene, AsGns5 was primed by both (2R,3R)-butanediol and PC1, while BTH did not affect the expression of homologs in A. stolonifera of BTH-inducible genes identified in other monocots, the WCI-2 lipoxygenase or the BCI-4 putative calcium-binding EF-hand.