Confirmation and Characterization of the First Case of Acetolactate Synthase (ALS)-Inhibitor—Resistant Wild Buckwheat (Polygonum convolvulus L.) in the United States

Balaji Aravindhan Pandian,Abigail Friesen,P V Vara Prasad,Mithila Jugulam,Dallas E Peterson,Martin Laforest

doi:10.3390/agronomy10101496

Balaji Aravindhan Pandian, Abigail Friesen + Show 4 more

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https://doi.org/10.3390/agronomy10101496

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Abstract

Wild buckwheat (Polygonum convolvulus L.) is a problem weed and ALS-inhibitors (e.g., chlorsulfuron) are commonly used for its management. Recently, a population of wild buckwheat (KSW-R) uncontrolled with ALS-inhibitors was found in a wheat field in Kansas, USA. The objectives of this research were to determine the level and mechanism of resistance to chlorsulfuron and cross resistance to other ALS-inhibitors in the KSW-R population. In response to chlorsulfuron rates ranging from 0 to 16x (x = 18 g ai/ha), the KSW-R wild buckwheat was found >100-fold more resistant compared to a known ALS-inhibitor susceptible (KSW-S) wild buckwheat. Also, >90% of KSW-R plants survived field recommended rates of sulfonylurea but not imidazolinone family of ALS-inhibitors. A portion of the ALS gene covering all previously reported mutations known to bestow resistance to ALS-inhibitors was sequenced from both KSW-R and KSW-S plants. The Pro-197-Ser substitution that confers resistance to the sulfonylurea herbicides was found in KSW-R plants. Our results support the evolution of high level of chlorsulfuron resistance as a result of a mutation in the ALS-gene in KSW-R buckwheat. This is the first case of resistance to any herbicides in wild buckwheat in the US.

Highlights

Wild buckwheat (Polygonum convolvulus L.) is a summer annual weed, commonly found in small grain crops such as wheat (Triticum aestivum) and oats (Avena sativa)
This population was designated as KSW-R and a biotype known to be susceptible to acetolactate synthase (ALS)-inhibitors, collected in Kansas (KSW-S) was used in this study for comparison
The GR50 of the KSW-R buckwheat was higher than the highest rate used (288 g ai ha−1 ) in this study; and the biomass reduction of KSW-R buckwheat was

Summary

Introduction

Wild buckwheat (Polygonum convolvulus L.) is a summer annual weed, commonly found in small grain crops such as wheat (Triticum aestivum) and oats (Avena sativa). This weed was introduced into the US from Europe via grain transport and became a problem weed throughout the Great Plains, Northern Plains, Canada’s Prairie provinces, and US Midwest. Wild buckwheat is a competitive weed that can cause yield losses of up to 66% in wheat. Apart from competing for nutrients, the vines of wild buckwheat can tangle and climb on the shoots of host plants which interferes in harvesting operations leading to lower yields and poor quality [1,2]. Control of wild buckwheat in these crops is largely dependent on the use of acetolactate synthase (ALS)-inhibiting herbicides

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