Herbicide resistance in grain sorghum

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dc.contributor.author Kershner, Kellan Scott
dc.date.accessioned 2011-11-04T15:25:34Z
dc.date.available 2011-11-04T15:25:34Z
dc.date.issued 2011-11-04
dc.identifier.uri http://hdl.handle.net/2097/13069
dc.description.abstract Sorghum acreage is declining throughout the United States because management options and yield have not maintained pace with maize improvements. The most extreme difference has been the absence of herbicide technology development for sorghum over the past twenty years. The objectives of this study were to evaluate the level of resistance, type of inheritance, and causal mutation of wild sorghums that are resistant to either acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides or acetohydroxyacid synthase (AHAS)-inhibiting herbicides. ACCase-inhibiting herbicides used in this study were aryloxyphenoxypropionate (APP) family members fluazifop-P and quizalofop-P along with cyclohexanedione (CHD) family members clethodim and sethoxydim. The level of resistance was very high for APP herbicides but low to nonexistent to CHD herbicides. With genetic resistance to APP herbicides, the resistance factors, the ratio of resistance to susceptible, were greater than 54 to 64 for homozygous individuals and greater than 9 to 20 for heterozygous individuals. Resistance to CHD herbicides was very low with resistance factors ranging from one to about five. Genetic segregation studies indicate a single gene is the cause of resistance to APP herbicides. Sequencing identified a single mutation that results in cysteine replacing tryptophan (Trp-2027-Cys). Trp-2027-Cys has previously been reported to provide resistance to APP but not CHD herbicides. The other wild sorghum evaluated in this study was resistant to AHAS-inhibiting herbicides including imidazolinone (IM) family member, imazapyr, and sulfonylurea (SU) family member, nicosulfuron. Resistance factors in this genotype were very high, greater than 770 for the IM herbicide and greater than 500 for the SU herbicide, for both herbicide chemical families. Genetic segregation studies demonstrate that resistance was controlled by one major locus and two modifier loci. DNA sequencing of the AHAS gene identified two mutations, Val-560-Ile and Trp-574-Leu. Val-560-Ile is of unknown importance, but valine and isoleucine are similar and residue 560 is not conserved. Trp-574 is a conserved residue and Leu-574 is a known mutation that provides strong cross resistance to IM and SU herbicides. The results of these studies suggest that these sources of APP, SU, and IM resistance may provide useful herbicide resistance traits for use in sorghum. en_US
dc.language.iso en_US en_US
dc.publisher Kansas State University en
dc.subject Target site resistance of genetic herbicide resistance en_US
dc.subject Acelolactate synthase (ALS) en_US
dc.subject Herbicide resistance grain sorghum dose response en_US
dc.subject Acetohydroxyacid synthase (AHAS) en_US
dc.subject Herbicide resistance weeds dose response en_US
dc.subject Acetyl-coenzyme A carboxylase (ACCase) en_US
dc.title Herbicide resistance in grain sorghum en_US
dc.type Dissertation en_US
dc.description.degree Doctor of Philosophy en_US
dc.description.level Doctoral en_US
dc.description.department Department of Agronomy en_US
dc.description.advisor Kassim Al-Khatib en_US
dc.description.advisor Mitchell R. Tuinstra en_US
dc.subject.umi Agronomy (0285) en_US
dc.subject.umi Genetics (0369) en_US
dc.subject.umi Plant Sciences (0479) en_US
dc.date.published 2010 en_US
dc.date.graduationmonth December en_US


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