Submitted to: Biennial Conference on Molecular and Cellular Biology of the Soybean
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2010
Publication Date: 8/8/2010
Citation: Walker, D.R., George, G., Marois, J.J., Wright, D.L. 2010. Age-Dependent Variations in Systemic Defense Responses of Soybean Plants towards Soybean Rust Caused by Phakopsora pachyrhizi [abstract]. 13th Biennial Molecular & Cellular Biology of the Soybean Conference 2010. http://www.ncsu.edu/project/OPDWebSpace/MCBSpdfs/281.pdf. Interpretive Summary:
Technical Abstract: Despite the identification of several key mechanisms underlying disease resistance, comparatively little is known about the way developmental factors affect the capability of plants to defend themselves against pathogens. In this study, the influence of plant age on inducible systemic defense responses in the interactions between two susceptible soybean cultivars (Williams 82 and Benning) and Phakopsora pachyrhizi were investigated. Saccharin was tested for its capacity to induce systemic acquired resistance (SAR) that would suppress soybean rust under greenhouse conditions. Plants were grown hydroponically in half-strength Hoagland’s solution and were challenged with the pathogen at 1, 5, 10 and 15 days after 3 mM saccharin had been applied as either a foliar spray or a root drench at the 2nd trifoliate (V3) or early reproductive (R1) stage. Plants were assessed for rust infection 2 weeks after inoculation. Leaf position and mode of saccharin application were significant factors in determining the severity of rust infection. Saccharin applied as a root drench was more effective than the leaf application at inducing SAR, with increased resistance observed 1 day after application and still apparent 15 days after application. In contrast, foliar treatment with saccharin did not increase systemic protection until 15 days after treatment. Results from these assays also suggest that younger plants exhibited a stronger SAR response than more mature ones.