Dr. Riechers investigates how plants respond and adapt to stress caused by herbicides. He explains herbicide-resistance mechanisms and describes herbicide safener mode of action by discovering new genes and proteins that rapidly detoxify herbicides. His work leads to an increased margin of selectivity between cereal crops and difficult-to-control weeds.
Characterizing the Interaction Between Mesotrione and Atrazine
Broadleaf weeds such as waterhemp and kochia have evolved resistance to many different classes of herbicides, with some biotypes having 'multiple resistance', meaning resistance to more than one class of herbicides in the same plant. HPPD-inhibiting herbicides, such as Callisto (mesotrione) and Balance Pro (isoxaflutole), are relatively new herbicides with excellent activity on these problem broadleaf weeds. Since these herbicides have only been used in corn for a few years, weed resistance to HPPD inhibitors has not developed so far. Callisto is often tank-mixed with a low amount of atrazine, a photosystem II inhibitor, and displays synergistic herbicidal activity on waterhemp and pigweeds when applied postemergence. In addition to improving weed control with the Callisto plus atrazine tank mix, this weed management strategy may also aid in preventing or delaying the development of weed resistance to Callisto through the combination of herbicides having two distinct target sites and modes of action. Interestingly, the synergism between Callisto and atrazine has also been documented in atrazine-resistant waterhemp and pigweed biotypes. Ongoing greenhouse and laboratory studies are aimed at determining the underlying physiological basis for this interaction.
Soybean Injury from Plant Growth Regulator (PGR) Herbicides
Several auxin-like herbicides (dicamba, clopyralid, 2,4-D) commonly used in corn for postemergence weed control can injure soybeans at extremely low rates. These plant growth regulator (PGR) herbicides can drift onto nearby soybean fields, or can be directly applied at very low rates if spray tanks are not thoroughly cleaned before spraying soybeans. These herbicides can cause severe injury to newly emerging soybean leaves, and also delayed maturity and decreased yield. Injury symptoms include leaf cupping, strapping, parallel veination, and puckering.
We are working on developing a laboratory assay to detect the presence of these PGR herbicides in soybean leaves, based on their effects on gene expression levels and expression patterns. Using molecular techniques such as RT-PCR and differential display of mRNA, we can fingerprint the expression of one or many genes in soybean leaves that have been treated with very low levels of the PGR herbicides. We hope to find a gene (or genes) that is only expressed in PGR-treated soybean leaves, and will then use the expression of this gene as a molecular marker to diagnose the presence of the herbicide. We have already found an auxin-regulated gene that is only expressed in soybean leaves treated with each of the three PGR herbicides listed above. We also hope to find specific genes that can be used to distinguish among dicamba, clopyralid, and 2,4-D.
- Characterization of Glutathione S-Transferases (GSTs) in Triticum tauschii We have cloned and sequenced three GST genes from Triticum tauschii, which is a wild progenitor of cultivated wheat, Triticum aestivum. We are utilizing T. tauschii as a model plant system to study the regulation of GST gene expression by herbicide safeners. Reasons for using T. tauschii as a model system are that it is diploid, contains the D genome found in cultivated wheat (ABD genomes), and also responds to safeners in a similar manner as cultivated wheat. Herbicide safeners protect grass crops from herbicide injury by increasing the activity of herbicide detoxification enzymes, such as GSTs and cytochrome P-450s. The precise reason and molecular mechanism for this induction of GST activity is not known. One theory is that safeners cause a stress response in the plant that leads to transcriptional activation of defense genes, such as GSTs. We hope to gain insight into safener mode of action by understanding the mechanism for activation of GST gene expression in response to safeners and various plant hormones. Currently, we are examining the promoters of the GST genes from T. tauschii for regulatory elements that might be involved with transcriptional activation and increased expression following herbicide safener treatment. Previous research mapped homoeologous copies of the GST genes to the short arms of chromosomes 6A, 6B, and 6D in cultivated wheat. Recent research findings show that only the GST genes on chromosome 6D are expressed in safener-treated wheat shoots. We plan to compare the promoters of the GST genes from 6A, 6B, and 6D to help identify critical regulatory elements involved in the safener response that might be missing from the promoters of non-responsive GST genes on chromosomes 6A and 6B.
Chapters in Books
- Riechers, D.E., K.C. Vaughn, and W.T. Molin. 2005. The role of plant glutathione S-transferases in herbicide metabolism. In Environmental Fate and Safety Management of Agrochemicals, J.M. Clark, H. Ohkawa, eds., ACS Symposium Series 899, American Chemical Society, Washington DC, pp. 216-23
Selected Articles in Journals
- Hausman, N.E., S. Singh, P.J. Tranel, D.E. Riechers, S.S. Kaundun, N.D. Polge, D.A. Thomas, and A.G. Hager. 2011. Resistance to HPPD-inhibiting herbicides in a population of waterhemp (Amaranthus tuberculatus) from Illinois, United States. Pest Manag. Sci. 67:258-261.
- Mithila, J., J.C. Hall, W.G. Johnson, K.B. Kelley, and D.E. Riechers. 2011. Evolution of resistance to auxinic herbicides: historical perspectives, mechanisms of resistance, and implications for broadleaf weed management in agronomic crops. Weed Sci. 59:445-457.
- Riechers, D.E., K. Kreuz, and Q. Zhang. 2010. Detoxification without intoxication: herbicide safeners activate plant defense gene expression. Plant Physiol. 153:3-13.
- A.J. Woodyard, J.A. Hugie, and D.E. Riechers. 2009. Interactions of mesotrione and atrazine in two weed species with different mechanisms for atrazine resistance. Weed Sci. 57:369-378.
- A.J. Woodyard, G.A. Bollero, and D.E. Riechers. 2009. Broadleaf weed management in corn utilizing synergistic postemergence herbicide combinations. Weed Technol. 23:513-518.
- A. S. Davis, J. C. Hall, M. Jasieniuk, M. A. Locke, E. C. Luschei, D. A. Mortensen, D. E. Riechers, R. G. Smith, T. M. Sterling, and J. H. Westwood. 2009. Weed science research and funding: a call to action. Weed Sci. 57:442-448.
- Pataky, J.K., M.M. Williams II, D.E. Riechers and M.D. Meyer. 2009. A common genetic basis for cross-sensitivity to mesotrione and nicosulfuron in sweet corn hybrid cultivars and inbreds grown throughout North America. J. Amer. Soc. Hort. Sci. 134:252-260.
- Hugie, J.A., G. Bollero, P.J. Tranel, and D.E. Riechers. 2008. Defining the rate requirements for synergism between mesotrione and atrazine in redroot pigweed (Amaranthus retroflexus). Weed Sci. 56:265-270.
- Zhang, Q., and D.E. Riechers. 2008. Proteomics: an emerging technology for weed science research. Weed Sci. 56:306-313.
- Nordby, J.N., M.M. Williams II, J.K. Pataky, D.E. Riechers, and J.D. Lutz. 2008. A common genetic basis in sweet corn inbred Cr1 for cross sensitivity to multiple cytochrome P450-metabolized herbicides. Weed Sci. 56:376-382.
- Kelley, K.B., and D.E. Riechers. 2007. Recent developments in auxin biology and new opportunities for auxinic herbicide research. Pestic. Biochem. Physiol. 89:1-11.
- Volenberg, D.S., P.J. Tranel, J.F. Holt, F.W. Simmons, S.C. Weller, A. Sharkhuu, and D.E. Riechers. 2007. Assessment of two biotypes of Solanum ptycanthum that differ in resistance levels to imazamox. Weed Res. 47:353-363.
- Zhang, Q, F.-X. Xu, K.N. Lambert, and D.E. Riechers. 2007. Safeners coordinately induce the expression of multiple proteins and MRP transcripts involved in herbicide metabolism and detoxification in Triticum tauschii seedling tissues. Proteomics 7:1261-1278.
- Kelley, K.B., Q. Zhang, K.N. Lambert, and D.E. Riechers. 2006. Evaluation of auxin-responsive genes in soybean for detection of off-target plant growth regulator herbicides. Weed Sci. 54:220-229.
- Pataky, J.K., J.N. Nordby, M.M. Williams, and D.E. Riechers. 2006. Inheritance of cross-sensitivity in sweet corn to herbicides applied postemergence. J. Amer. Soc. Hort. Sci. 131:744-751.
- Bierman, R.E., D.E. Riechers, C.L. Sprague, G. Bollero, and W.L. Pedersen. 2006. Fungicide-herbicide interaction in soybean (Glycine max). Crop Prot. 25:134-139.
- Reiling, K.L., F.W. Simmons, D.E. Riechers, and L.E. Steckel. 2006. Application timing and soil factors affect sulfentrazone phytotoxicity to two soybean (Glycine max (L.) Merr.) cultivars. Crop Prot. 25:230-234.
- Zhou, W., F.L. Kolb, and D.E. Riechers. 2005. Identification of proteins induced or up-regulated by Fusarium head blight infection in the spikes of hexaploid wheat (Triticum aestivum). Genome 48:770-780.
- Williams, M.M., J.K. Pataky, J.N. Nordby, D.E. Riechers, C.L. Sprague, and J.B. Masiunas. 2005. Cross-sensitivity in sweet corn to nicosulfuron and mesotrione applied postemergence. Hort. Sci. 40:1801-1805.
- Kelley, K.B., L.M. Wax, A.G. Hager, and D.E. Riechers. 2005. Soybean response to plant growth regulator herbicides is affected by other postemergence herbicides. Weed Sci. 53:101-112.
- Bunting, J.A., C.L. Sprague, and D.E. Riechers. 2005. Incorporating foramsulfuron into annual weed control systems for corn. Weed Technol. 19:160-167.
- Holappa, L.D., M.K. Walker-Simmons, T.H.D. Ho, D.E. Riechers, D.M. Beckles, and R.L. Jones. 2005. A Triticum tauschii protein kinase related to wheat PKABA1 is associated with ABA signaling and is distributed between the nucleus and cytosol. J. Cereal Sci. 41:333-346.
- Bunting, J.A., C.L. Sprague, and D.E. Riechers. 2004. Proper adjuvant selection for foramsulfuron activity. Crop Prot. 23:361-366.
- Kelley, K.B., K.N. Lambert, A.G. Hager, and D.E. Riechers. 2004. Quantitative expression analysis of GH3, a gene induced by plant growth regulator herbicides in soybean. J. Agric. Food Chem. 52:474-478.
- Zhang, Q., and D.E. Riechers. 2004. Proteomic characterization of herbicide safener-induced proteins in the coleoptile of Triticum tauschii seedlings. Proteomics 4:2058-2071.
- Bunting, J.A., C.L. Sprague, and D.E. Riechers. 2004. Absorption and activity of foramsulfuron in giant foxtail (Setaria faberi) and woolly cupgrass (Eriochloa villosa) with various adjuvants. Weed Sci. 52:513-517.
- Bunting, J.A., C.L. Sprague, and D. E. Riechers. 2004. Physiological basis for tolerance of corn hybrids to foramsulfuron. Weed Sci. 52:711-717.
- Bunting, J.A., C.L. Sprague, and D.E. Riechers. 2004. Corn tolerance as affected by the timing of foramsulfuron applications. Weed Technol. 18:757-762.
- Milliman, L.D., D.E. Riechers, L.M. Wax, and F.W. Simmons. 2003. Characterization of two biotypes of imidazolinone-resistant eastern black nightshade. Weed Sci. 51:139-144.
- Riechers, D.E., Q. Zhang, F.-X. Xu, and K.C. Vaughn. 2003. Tissue-specific expression and localization of safener-induced glutathione S-transferase proteins in Triticum tauschii. Planta 217:831-840.
- Xu, F.-X., E.S. Lagudah, S. P. Moose, and D.E. Riechers. 2002. Tandemly duplicated safener-induced glutathione S-transferase genes from Triticum tauschii contribute to genome- and organ-specific expression in hexaploid wheat. Plant Physiol. 130:362-373.
- Riechers, D.E. and M.P. Timko. 1999. Structure and expression of the gene family encoding putrescine N-methyltransferase in Nicotiana tabacum: new clues to the evolutionary origin of cultivated tobacco. Plant Mol. Biol. 41:387-401.
- Riechers, D.E., A. Kleinhofs, G.P. Irzyk, and S.S. Jones. 1998. Chromosomal location and expression of a herbicide safener-regulated glutathione S-transferase gene in Triticum aestivum and linkage relations in Hordeum vulgare. Genome 41:368-372.
- Riechers, D.E., G. P. Irzyk, E.P. Fuerst, and S.S. Jones. 1997. Nucleotide sequence of a cDNA encoding a safener-induced glutathione S-transferase (accession no. AF004358) from Triticum tauschii (PGR97-110). Plant Physiol. 114:1568.
- Riechers, D.E., G.P. Irzyk, S.S. Jones, and E.P. Fuerst. 1997. Partial characterization of glutathione S-transferases from wheat (Triticum spp.) and purification of a safener-induced glutathione S-transferase from Triticum tauschii. Plant Physiol. 114:1461-1470.
- Riechers, D.E., K. Yang, G.P. Irzyk, S.S. Jones, and E.P. Fuerst. 1996. Variability of glutathione S-transferase levels and dimethenamid tolerance in safener-treated wheat and wheat relatives. Pestic. Biochem. Physiol. 56:88-101.
- Riechers, D.E., E.P. Fuerst, and K.D. Miller. 1996. Initial metabolism of dimethenamid in safened and unsafened wheat shoots. J. Agric. Food Chem. 44:1558-1564.
- Riechers, D.E., L.M. Wax, R.A. Liebl, and D.G. Bullock. 1995. Surfactant effects on glyphosate efficacy. Weed Technol. 9:281-285.
- Riechers, D.E., L.M. Wax, R.A. Liebl, and D.R. Bush. 1994. Surfactant-increased glyphosate uptake into plasma membrane vesicles isolated from common lambsquarters leaves. Plant Physiol. 105:1419-1425.
- Wade, B.R., D.E. Riechers, R.A. Liebl, and L.M. Wax. 1993. The plasma membrane as a barrier to herbicide penetration and site for adjuvant action. Pestic. Sci. 37:195-202.
- Riechers, D.E. 1991. Herbicide resistance in weeds. J. Agron. Educ. 20:63-65.
- Extension Publications
- Kelley, K., D. Riechers, D. Nordby, and A. Hager. 2004. Plant Growth Regulator Injury to Soybeans. Extension fact sheet, posted on the internet at: http://bulletin.ipm.illinois.edu/article.php?id=212
- Riechers, D.E., E.P. Fuerst, and C.M. Boerboom. 1994. Advancements in the development of seed-applied herbicide safeners for wheat. Wash. State Univ. Coop. Ext. Tech. Rep. 94-6, p. 102.
- Boerboom, C.M., E.P. Fuerst, and D.E. Riechers. 1993. Wheat safener research targeted for jointed goatgrass control. Wash. State Univ. Coop. Ext. Tech. Rep. 93-4, pp. 77-78.
- “Mechanisms of Herbicide Safeners in Enhancing Crop Protection”, BASF - Global Research Crop Protection, BioScience Research Symposium, Limburgerhof, Germany. 2011.
- “Development of Resistance to the Auxinic Herbicides: Historical Perspectives, Genetics, and Mechanisms of Weed Resistance”, Southern Weed Science Society Annual Meeting, San Juan, Puerto Rico. Symposium entitled “2,4-D - Past, Present, and Future.” 2011.
- “Development of Resistance to the Auxinic Herbicides: Historical Perspectives, Genetics, and Mechanisms of Weed Resistance”, North Central Weed Science Society Annual Meeting, Lexington, KY. Symposium entitled “2,4-D - Past, Present, and Future. Status of One of the World's Most Widely Used Herbicides.” 2010.
- “Application of Proteomics Techniques to Weed Science Research”, Weed Science Society of America annual meeting, Symposium entitled “Using Emerging Technologies to Study Weed Biology: an Educational Forum”, San Antonio, TX. 2007.
- “Role of Herbicide Metabolism in Weed Resistance to Herbicides”, American Chemical Society Symposium, Agrochemicals Division, San Francisco, CA. 2006.
- "Proteomics Approaches for Studying Herbicide Safener Mechanism of Action in Triticum tauschii Seedlings", BASF BioScience Research Symposium, St. Johann, Germany. 2005.
- "Regulation and Function of Herbicide Safener-Inducible Glutathione S-Transferases in the Model Grass Species Triticum tauschii", 4th Int'l. Weed Science Congress, Durban, South Africa. 2004.
- "Role of Plant Glutathione S-Transferases in Herbicide Metabolism", 3rd Pan Pacific Conference on Pesticide Science, Honolulu, HI, June 2003.
- "Analyzing Gene Expression at the Protein Level: Using Proteomics Techniques to Investigate Herbicide Safener Mechanism of Action", North Central Weed Science Society, Louisville, KY, December 2003.