ARS | Publication request: Saccharin-Mediated Systemic Protection of Soybean Against Infection by Soybean Rust

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2010
Publication Date: August 7, 2010
Citation: Srivastava, P., George, S., Marois, J., Wright, D., Walker, D.R. 2010. Saccharin-Mediated Systemic Protection of Soybean Against Infection by Soybean Rust [abstract]. American Phytopathological Society Annual Meeting, August 7-11,2010, Nashville, TN. Phytopathology 100:S122.

Technical Abstract: Systemic acquired resistance (SAR) is a widely distributed plant defense system that confers broad-spectrum disease resistance. Saccharin is known to induce a SAR response in many plant species. To evaluate the potentiating capability of saccharin in this respect, soybean (Glycine max) plants were inoculated with Phakopsora pachyrhizi urediniospores after application of saccharin, and were later rated for differences in the development of soybean rust symptoms. Plants were grown hydroponically in half strength Hoagland's solution and were challenged with pathogen at 1, 5, 10 and 15 days after treatment with 3 mM saccharin applied as either a foliar spray or a root drench at the 2nd trifoliate (V2) and early reproductive (R1) stages. Plants were destructively harvested and 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 treatment at inducing the 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. Application of saccharin, either to the leaf or as a root drench, had no significant effect on fresh and dry weight of plants, which suggests that induction of systemic resistance to rust infection using saccharin does not affect plant growth.