Location: Crop Genetics Research Unit
Title: Registration of Four Upland Cotton (Gossypium hirsutum L.) Genetic Stock Mutants with Tolerance to Imazamox Authors
Submitted to: Journal of Plant Registrations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 2009
Publication Date: May 1, 2010
Citation: Bechere, E., Auld, D.L., Dotary, P., Kebede, H.A. 2010. Registration of Four Upland Cotton (Gossypium hirsutum L.) Genetic Stock Mutants with Tolerance to Imazamox. Journal of Plant Registrations. 4:155-158 Interpretive Summary: Weed control in most cotton fields is by almost exclusive use of the broad-spectrum herbicide glyphosate. With such dependence on one herbicide has come concern for development and spread of weeds that are tolerant (not killed) to this herbicide. Cotton lines with tolerance to another herbicide with a different mode of action will increase weed management tools available to cotton growers. Eight commercial cotton varieties were treated with a chemical that causes changes to plant DNA, and selections from these mutant populations produced four lines that exhibited elevated levels of tolerance to imazamox, another herbicide that kills a broad spectrum of weeds. The imazamox-tolerant mutants developed into normal plants when sprayed with the herbicide, while the non-mutated cultivars turned yellow, were stunted and their lint yield were substantially reduced. Application of imazamox at twice the normal rate reduced lint yield of the tolerant lines by only 2-3 % whereas the yields of the non-mutated susceptible lines were reduced by 22-41 %. Imazamox doses did not have significant effect on fiber quality. These cotton lines with tolerance to imazamox can be used to develop cultivars that can be used in fields where the use of glyphosate is no longer an effective option.
Technical Abstract: Few mutants conferring herbicide tolerance in cotton (Gossypium hirsutum L.) have been developed. Imazamox is a broad spectrum imidazolinone herbicide that could give growers a new tool to control many troublesome annual broadleaf and grass weeds. The objective was to identify imazamox tolerance in chemical mutation derived cotton lines. Four imazamox tolerant mutant cotton (Gossypium hirsutum L.) genetic stocks (SCM3-4-3, SCM3-7-3, RM3-8-1 and EM4-3-1 were developed and jointly released by Texas Tech University, Department of Plant and Soil Science and USDA-ARS, Crop Genetics and Production Research Unit, Stoneville, Mississippi in July, 2009. These genetic stocks were obtained through ethyl methanesulfonate (EMS) mutagenesis of seeds of three High Plains cotton cultivars (‘SC 9023’, ‘Rocket’ and ‘Explorer’) and selection with imazamox herbicide. Application of five rates of imazamox (0, 88, 175, 350, and 700 g a.i. ha-1) has shown that these mutants have elevated levels of tolerance to imazamox. These genetic stocks are available for use by the cotton industry and public researchers to create hybrids, parental lines, or germplasm lines with resistance to the imazamox herbicide. The identification of these mutants is expected to increase weed management options available to conventional growers who have become heavily dependent on glyphosate based crop production systems.