Full TGIF Record # 76817
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Web URL(s):http://www.wsweedscience.org//wp-content/uploads/proceedings-archive/2001.pdf#page=61
    Last checked: 12/10/2013
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Publication Type:
Content Type:Abstract or Summary only
Author(s):Dyer, William E.; Cranston, Harwood J.; Kern, Anthony J.
Author Affiliation:Dyer: Professor; Cranston and Kern: Graduate Research Assistants, Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT
Title:Physiological characterization of dicamba resistance in kochia
Section:Basic sciences
Other records with the "Basic sciences" Section
Meeting Info.:Coeur D'Alene, ID: March 12-15, 2001
Source:Proceedings of the Western Society of Weed Science. Vol. 54, 2001, p. 53.
# of Pages:1
Publishing Information:Newark, CA: Western Society of Weed Science
Keywords:TIC Keywords: Dicamba; Herbicide resistance; Bassia; MCPA; 2,4-DB; Picloram; Sulfonylurea herbicides; Imidazolinone herbicides; Proteins; Rates; Weed control
Abstract/Contents:"Extensive use of the auxinic herbicide dicamba has selected for resistant (R) kochia populations in several areas of the United States. Dose response studies show that an inbred R line derived from plants collected near Fort Benton, MT is 4- to 5-fold more tolerant to dicamba than susceptible (S) plants. This line is also resistant to related auxinic herbicides MCPA, 2,4-DB, and picloram as well as to the unrelated sulfonylurea and imidazolinone herbicides. Other populations with resistance to fluroxypyr have been verified. Resistance to dicamba cannot be attributed to altered rates of herbicide uptake, translocation or metabolism. We are currently investigating the hypothesis that resistance is conferred by reduced herbicide binding to the auxin receptor protein (a.k.a auxin binding protein, ABP) on the cell surface. We speculate that such a mutation in ABP may also affect endogenous auxin binding and thus alter auxin-mediated responses such as gravitropism and root growth inhibition. The gravitropic responses of 6-cm tall R and S kochia seedlings were compared by determining rates of stem vertical reorientation after the plants were shifted to a horizontal position. The rate of stem bending in two S accessions was 3.9° per 10 min, while the rate of the dicamba-resistant inbred line was only 1.2° per 10 min. Interestingly, the rate of an accession with resistance to both dicamba and fluroxypyr was intermediate at 2.4° per 10 min. These results show that the gravitropic response in R kochia is impaired, and suggest that a perturbation of auxin perception or signal transduction could be responsible for this phenotype. Further studies examining the effects of exogenous indoleacetic acid (IAA) and synthetic auxins on root growth inhibition showed that R plants were less sensitive than S plants. To compare rates of auxin-inducible gene expression in R and S kochia, suspension cell cultures will be treated with IAA and mRNA levels of ACC synthase, a gene known to be rapidly induced by auxin, will be determined. We are currently attempting to clone the kochia ABP using a combination of PCR and library screening with heterologous probes. Our eventual goal is to obtain and compare the DNA sequences of ABP from R and S kochia. The evolution of weed populations like these with resistance to several unrelated herbicides is particularly troubling, and underscores the need to implement effective herbicide resistance management strategies."
Note:"Paper Number 80"
This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Dyer, W. E., H. J. Cranston, and A. J. Kern. 2001. Physiological characterization of dicamba resistance in kochia. Proc. West. Soc. Weed Sci. 54:p. 53.
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    Last checked: 12/10/2013
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MSU catalog number: SB 610 .W43 v.49
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