Molecular Basis of Evolved Resistance to Glyphosate and Acetolactate Synthase-Inhibitor Herbicides in Kochia (Kochia scoparia) Accessions from Montana

Content Provider	Scilit
Author	Kumar, Vipan Jha, Prashant Giacomini, Darci Westra, Eric P. Westra, Philip
Copyright Year	2015
Description	The rapid evolution and spread of glyphosate-resistant (GR) kochia in the Northern Great Plains is an increasing threat to GR cropping systems and conservation tillage practices common in this region. GR kochia accessions with 4.6- to 11-fold levels of resistance to glyphosate have recently been reported in Montana. Those GR kochia accessions were also suspected to be resistant to acetolactate synthase (ALS) inhibitors, i.e., multiple herbicide-resistant (MHR) kochia. In this research, the level of resistance to the ALS-inhibitor herbicides (sulfonylureas) and the molecular mechanisms conferring resistance to glyphosate and ALS-inhibitor herbicides in MHR kochia was investigated. On the basis of whole-plant dose–response assays, MHR kochia accessions (GIL01, JOP01, and CHES01) were 9.3- to 30-fold more resistant to premixed thifensulfuron methyl + tribenuron methyl + metsulfuron methyl than the susceptible (SUS) accession. In an in vivo leaf-disk shikimate assay, MHR plants accumulated less shikimate than the SUS plants at a discriminate dose of 100 μM glyphosate. Sequencing of the conserved region ofEPSPSrevealed no target-site mutation at $Thr_{102}$or $Pro_{106}$residue. MHR kochia accessions had increased relativeEPSPSgene copies (~ 4 to 10) compared with the SUS accession (single copy). Furthermore, MHR kochia accumulated higher EPSPS protein compared with the SUS plants. Resistance to the ALS-inhibitor herbicides was conferred by $Pro_{197}$amino acid substitution (proline to glutamine).EPSPSgene amplification and a single target-site mutation at $Pro_{197}$inALSgene confer resistance to glyphosate and ALS-inhibitor herbicides, respectively, in MHR kochia accessions from Montana. This is the first confirmation of occurrence of MHR kochia in Montana.
Related Links	https://www.cambridge.org/core/services/aop-cambridge-core/content/view/437557374C5019C3E36CABCD99B683CC/S004317450001479Xa.pdf/div-class-title-molecular-basis-of-evolved-resistance-to-glyphosate-and-acetolactate-synthase-inhibitor-herbicides-in-kochia-span-class-italic-kochia-scoparia-span-accessions-from-montana-div.pdf
Ending Page	769
Page Count	12
Starting Page	758
ISSN	00431745
e-ISSN	15502759
DOI	10.1614/ws-d-15-00021.1
Journal	Weed Science
Issue Number	4
Volume Number	63
Language	English
Publisher	Cambridge University Press (CUP)
Publisher Date	2015-12-01
Access Restriction	Open
Subject Keyword	Weed Science Inhibitor Herbicides Kochia Accessions
Content Type	Text
Resource Type	Article
Subject	Plant Science Agronomy and Crop Science