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November 17, 2005
Glyphosate inhibits rust
diseases in glyphosate-resistant wheat and soybean
Paul C. C. Feng, G. James Baley, William P. Clinton, Greg J.
Bunkers, Murtaza F. Alibhai, Timothy C. Paulitz, and Kimberlee
K. Kidwell
Monsanto Biotechnology Research, St. Louis, MO 63017; Department
of Crop and Soil Sciences, Washington State University, Pullman,
WA 99164-6420; and Root Disease and Biological Control Research
Unit, Agricultural Research Service, U.S. Department of
Agriculture, Pullman, WA 99164-6430
PNAS published 17 November 2005, 10.1073/pnas.0508873102
Communicated by R. James Cook,
Washington State University, Pullman, WA, October 11,
2005 (received for review July 19, 2005)
ABSTRACT
Glyphosate is a broad-spectrum
herbicide used for the control of weeds in
glyphosate-resistant crops. Glyphosate inhibits
5-enolpyruvyl shikimate 3-phosphate synthase, a key enzyme in
the synthesis of aromatic amino acids in plants, fungi,
and bacteria. Studies with glyphosate-resistant wheat
have shown that glyphosate provided both preventive
and curative activities against Puccinia
striiformis f. sp. tritici and Puccinia triticina,
which cause stripe and leaf rusts, respectively, in wheat.
Growth-chamber studies demonstrated wheat rust
control at multiple plant growth stages with a
glyphosate spray dose typically recommended for weed
control. Rust control was absent in formulation controls
without glyphosate, dependent on systemic glyphosate
concentrations in leaf tissues, and not mediated
through induction of four common systemic acquired
resistance genes. A field test with endemic stripe
rust inoculum confirmed the activities of glyphosate
pre- and postinfestation. Preliminary greenhouse studies also
demonstrated that application of glyphosate in
glyphosate-resistant soybeans suppressed Asian
soybean rust, caused by Phakopsora pachyrhizi.
Source: Proceedings of the National
Academy of Sciences of the United States of America
http://www.pnas.org/cgi/content/abstract/0508873102v1?etoc |
