Transfer and Expression of ALS Inhibitor Resistance from Palmer Amaranth (Amaranthus palmeri) to an A. spinosus × A. palmeri Hybrid

Transfer of herbicide resistance among closely related weed species is a topic of growing concern. A spiny amaranth × Palmer amaranth hybrid was confirmed resistant to several acetolactate synthase (ALS) inhibitors including imazethapyr, nicosulfuron, pyrithiobac, and trifloxysulfuron. Enzyme assays...

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Bibliographic Details
Published in:Weed science 2016-04, Vol.64 (2), p.240-247
Main Authors: Molin, William T, Nandula, Vijay K, Wright, Alice A, Bond, Jason A
Format: Article
Language:English
Subjects:
Acetolactate synthase
ALS enzyme
Cloning
Crops
cross resistance
Herbicides
hybrid
Hybridization
Mutation
PHYSIOLOGY/CHEMISTRY/BIOCHEMISTRY
Population
Weeds
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Summary:Transfer of herbicide resistance among closely related weed species is a topic of growing concern. A spiny amaranth × Palmer amaranth hybrid was confirmed resistant to several acetolactate synthase (ALS) inhibitors including imazethapyr, nicosulfuron, pyrithiobac, and trifloxysulfuron. Enzyme assays indicated that the ALS enzyme was insensitive to pyrithiobac and sequencing revealed the presence of a known resistance conferring point mutation, Trp574Leu. Alignment of the ALS gene for Palmer amaranth, spiny amaranth, and putative hybrids revealed the presence of Palmer amaranth ALS sequence in the hybrids rather than spiny amaranth ALS sequences. In addition, sequence upstream of the ALS in the hybrids matched Palmer amaranth and not spiny amaranth. The potential for transfer of ALS inhibitor resistance by hybridization has been demonstrated in the greenhouse and in field experiments. This is the first report of gene transfer for ALS inhibitor resistance documented to occur in the field without artificial/human intervention. These results highlight the need to control related species in both field and surrounding noncrop areas to avoid interspecific transfer of resistance genes. Nomenclature: Imazethapyr, nicosulfuron, pyrithiobac, trifloxysulfuron, Palmer amaranth Amaranthus palmeri S. Wats, spiny amaranth (Amaranthus spinosus L.).
ISSN:0043-1745
1550-2759
DOI:10.1614/WS-D-15-00172.1