PPO Inhibitor Resistance

PPO Inhibitor Resistance



A protoporphyrinogen oxidase (PPO-) inhibitor has shown to be an effective pre- and post-herbicide for pigweed control. However, due to its increase in usage to combat the glyphosate-resistant weeds, resistance to PPO-inhibitors is becoming a growing problem in pigweeds. A codon deletion at the 210th amino acid position ∆G210 in the gene coding for the PPO enzyme (PPX2L, also known as PPO2) is the most common mechanism for the resistance to PPO-inhibiting herbicides in waterhemp and Palmer amaranth (Wuerffel et al., 2015).

NAGC’s has expanded the pigweed genotyping panel to include detection of the altered target-site at ∆G210 that is linked to resistance to PPO-inhibiting herbicides. NAGC optimized and validated a DNA-based test for determining the presence of the altered site by expanding upon the information previously published (Wuerffel et al., 2015; Giacomini et al., 2017) as a starting point for the validation. The allelic-discrimination assay for detecting the wild-type and mutated forms of the PPX2L gene will help assess the level of PPO-inhibiting herbicide resistance in pigweed populations.

This project was funded in part by the North Dakota Department of Agriculture Bioscience Innovation Grant, the North Dakota Soybean Council, and the North Harvest Bean Growers Association.


Giacomini, D., Westra, P. & Ward, S. M. 2017. Impact of Genetic Background in Fitness Cost Studies: An Example from Glyphosate-Resistant Palmer Amaranth. Weed Science, 62, 29-37.

Wuerffel, R., Young, J., Tranel, P. & Young, B. 2015. Soil-Residual PPO-Inhibiting Herbicides Influence the Frequency of Associated Resistance in Amaranthus tuberculatus. Weed Science, 63, 150304134216007.

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