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| The Weed Physiology lab at
M.S.U. studies applied
agricultural problems using the tools of molecular biology and genetics.
We seek to understand the physiological strategies used by plants
that are highly successful as weeds in agricultural settings. |
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| Papers and Information from Weed Physiology | ||||||
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The Team!
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| One widespread strategy used by many weedy species is the production of dormant seeds. By shedding seeds with multiple dormancy phenotypes, parental plants spread out their reproductive effort over time and ensure a steady supply of individuals in the soil seedbank that can reinfest crop fields. Even though seed dormancy has been studied for over 100 years, our understanding of the underlying mechanisms controlling its maintenance and release remains rudimentary. Our approach has been to use differential display to obtain more than 30 cDNAs for mRNAs differentially expressed in dormant or nondormant Avena fatua (wild oat) embryos during early imbibition. | ||||||
| Dyer,
W. E. 1993. Dormancy-associated embryonic mRNAs and proteins in imbibing Avena
fatua L. caryopses.Physiol.
Plant. 88:201-211.
Dyer,
W.E. 1995. Exploiting Weed Seed Dormancy and Germination
Requirements through Agronomic Practices. Weed Sci. 43:498-503.
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| mRNAs expressed early during imbibition of nondormant embryos were determined to encode proteins such as alanine aminotransferase, cyc07 (a cyclin), and a sar-like monomeric GTP-binding protein, and these may have utility as markers for the very early events of germination. | ||||||
| Cranston,H. J., A. J. Kern, S. A.
Gerhardt, and W. E. Dyer.
1996. Wound-induced ethylene and germination of embryos excised
from dormant Avena fatua L. caryopses.
Intl. J. Plant Sci. 157:153-158.
Cranston, H.J., R.R. Johnson, M.E. Chaverra, and W.E. Dyer.1999. Isolation and characterization of a cDNA encoding a sar-like monomeric GTP-binding protein in Avena fatua L. Plant Sci. 145:75-81. |
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| In dormant seeds, endosperm tissue contained full-length mRNAs as well as very stable mRNA decay intermediates for homologs of the barley protein z and the wheat puroindoline a. Following a 14-month dry after-ripening period to relieve dormancy, intact mRNAs for these proteins were not detectable although decay intermediates were maintained at similar levels. Our current studies focus on the mechanism(s) by which these mRNA decay intermediates are stabilized in mature endosperm tissue. | ||||||
| Johnson,
R.R., M.E. Chaverra, H.J. Cranston, and W.E. Dyer. 1999.
Degradation of oat mRNAs during seed development. Plant Mol.
Biol.
39:823-833. Johnson, R.R. and W.E. Dyer. 2000. Degradation of endosperm mRNAs during dry after-ripening of cereal grains. Seed Sci. Res. (In press). |
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| We have also taken a genetic approach to investigate quantitative trait loci (QTL) that control seed dormancy and resistance to pre-harvest sprouting in barley. | ||||||
| Oberthur,
L., W. E. Dyer, S. E. Ullrich, and T. K. Blake. 1995. Genetic
analysis of seed dormancy in barley (Hordeum
vulgare). J. Quant. Trait
Loci
1:5 http://probe.nalusda.gov:8000/otherdocs/jqtl1995-05/dormancy.html Larson, S., G. Bryan, W. Dyer, and T. Blake. 1996. Evaluation of gene effects of a major barley seed dormancy QTL in reciprocal backcrosses. J. Quant. Trait Loci http://probe.nalusda.gov:8000/otherdocs/jqtl/jqtl1996-04/larson15a.htm |
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| A second major focus of the lab concerns the mechanisms of evolved herbicide resistance in several weed species. Research on sulfonylurea herbicide-resistant Kochia scoparia populations showed that resistance was due to several different mutations conferring multiple patterns of cross-resistance to related herbicide families. Further, resistance was correlated with increased levels of branched chain amino acids in seed tissues, and resistant lines germinated faster at low temperatures than their susceptible counterparts. | ||||||
| Dyer,
W. E., P. W. Chee, and P. K. Fay. 1993.
Rapid germination of sulfonylurea-resistant Kochia
scoparia accessions is associated with elevated
seed levels of branched chain amino acids.
Weed Sci. 41:18-22. Sivakumaran, K., D. Mulugeta, P. K. Fay, and W. E. Dyer. 1993. Differential herbicide response among sulfonylurea-resistant Kochia scoparia L. accessions. Weed Sci. 41:159-165. Mulugeta, D., Dyer, W. E., B. D. Maxwell, and P. K. Fay. 1994. Kochia scoparia L. (Schrad) pollen dispersion, viability, and germination. Weed Sci. 42:548-552. |
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| Long term use of the herbicide triallate (Far-Go) in Montana and Canada has led to selection of resistant A. fatua accessions. Greenhouse studies showed that all accessions were also cross-resistant to the unrelated herbicide difenzoquat (Avenge). We showed that triallate resistance was due to a lack of metabolic activation of the herbicide and that difenzoquat resistance was conferred by binding of the herbicide in plant cell walls. | ||||||
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Kern, A. J., C. Colliver, B. D. Maxwell, P. K.
Fay, and W. E. Dyer. 1996.
Characterization of Wild Oat (Avena fatua L.) populations and an inbred
line with multiple herbicide resistance.
Weed Sci. 44:847-852.
Kern, A.J., D.M. Peterson, E.K. Miller, C.T. Colliver, and W.E. Dyer. 1996. Triallate resistance in Avena fatua L. is due to reduced herbicide activation. Pestic. Biochem. Physiol. 56:163-173. Kern, A.J., L.L. Jackson, and W.E. Dyer. 1997. Fatty acid and wax biosynthesis in susceptible and triallate-resistant Avena fatua L. Pestic. Sci. 51:21-26. Kern, A.J. and W.E. Dyer. 1998. Compartmental analysis of herbicide efflux in susceptible and difenzoquat-resistant Avena fatua L. suspension cells. Pestic. Biochem. Physiol. 61:27-37. Kern, A.J., B.E. Murray, M. Jasieniuk, B.D. Maxwell, and W.E. Dyer. 200_. Triallate resistance in wild oats (Avena fatua L.) is conferred by two recessive nuclear genes. (In preparation). |
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| A current project in the laboratory concerns the mechanisms, spatial population structure, and genetics of dicamba resistance in Kochia scoparia. Results to date show that resistance is not explained by reduced herbicide uptake or translocation, nor by increased metabolism. Efforts to examine herbicide binding and structures of auxin binding proteins are underway. | ||||||
| Cranston,
H.J., A. J. Kern, J.L. Hackett, E.K. Miller, B.D. Maxwell, and W.E. Dyer. 200_.
Dicamba resistance in Kochia scoparia
L. Schrad. (Dept. review). Jasieniuk, M., B.D. Maxwell, W.E. Dyer and T.K. Blake. 200_. Spatial structure of Kochia scoparia populations under directional selection. (In preparation). |
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| Increasing crop competitiveness is the most efficient weed management available. Developing crop cultivars with improved adaptations is the focus of many crop breeding programs. | ||||||
| Sivamani, Elumalai, Ahmed Bahieldin, Jon M. Wraith, Thamir Al-Niemi, William E. Dyer, Tuan-Hua David Ho, Rongda Qu. 2000. Improved biomass productivity and water use efficiency under water deficit conditions in transgenic wheat constitutively expressing the barley HVA1 gene. Plant Science. 155: 1-9. | ||||||
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Links to the homepage of publishers cited above:
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This
page is maintained by Meghan Trainor |
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Copyright notice: The materials listed below have been published in the respective journals cited, the only definitive repository of the content that has been certified and accepted after peer review. Copyright and all rights therein are retained by the respective publisher. This material may not be copied or reposted without explicit permission. |
