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Title: Mutations conferring increased glyphosate resistance in spring wheat, Triticum aestivum (L.)

item ARAMRAK, ATTAWAN - Washington State University
item LAWRENCE, NEVIN - Washington State University
item DEMACON, VICTOR - Washington State University
item CARTER, ARRON - Washington State University
item KIDWELL, KIMBERLEE - Washington State University
item BURKE, IAN - Washington State University
item Steber, Camille

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2017
Publication Date: 1/15/2018
Citation: Aramrak, A., Lawrence, N.C., Demacon, V.L., Carter, A.H., Kidwell, K.K., Burke, I.C., Steber, C.M. 2018. Mutations conferring increased glyphosate resistance in spring wheat, Triticum aestivum (L.). Crop Science. 58:84-97.

Interpretive Summary: This paper describes the identification of induced mutations in wheat that give increased resistance to the herbicide glyphosate, known commercially at Round Up(TM). This data tells us that it is possible to develop non-GMO glyphosate resistant lines in wheat. The genetics of these mutants was investigated.

Technical Abstract: A mutation breeding approach was used to recover glyphosate-resistant wheat lines as a first step towards exploring whether it is possible to develop non-genetically-modified (GM) glyphosate-resistant wheat lines. Currently, no GM glyphosate-resistant wheat cultivars are in production due to lack of consumer acceptance. Large-scale screening experiments recovered mutants able to tolerate 360 to 480 g ae ha-1 glyphosate in four spring wheat cultivars, ‘Hollis’, ‘Louise’, ‘Macon’, and ‘Tara2002’, indicating that it is possible to recover resistance in a wide range of genetic backgrounds. Glyphosate rates of 420 to 530 g ae ha-1 were sufficient to control the susceptible wild type (WT) parents. The genetics and physiology of seven glyphosate-tolerant (GT) mutants with promising levels of glyphosate resistance were characterized in depth. Glyphosate resistance was examined at the whole plant level based on dose-response experiments. Three mutant lines GTL33, GTH9-5, and GTT20 exhibited promising resistance based on a significant increase in GR50 (the dose required for a 50% growth reduction) compared to the corresponding susceptible wild type. When F2 segregation analysis was performed with 420 g ae ha-1 glyphosate, GTL1, GTL65, and GTT20 segregated as a single dominant gene, whereas GTL33, GTH9-5, and GTH9-8 appeared to be either a single semi-dominant or polygenic trait. The GTL33 and GTH9 mutations were not associated with nucleotide changes within the coding region of wheat EPSPS genes. Results suggest that glyphosate resistance can result from multiple genetic mechanisms.