Resistance level and target-site mechanism to fenoxaprop-p-ethyl in Beckmannia syzigachne (Steud.) Fernald populations from China

Lingxu Li1, Xiaoyong Luo1, and Jinxin Wang2*
Beckmannia syzigachne (Steud.) Fernald is one of the main grass weeds severely harming wheat (Triticum aestivum L.) production in rice-wheat areas in China. Fenoxaprop-p-ethyl is the main herbicide used to selectively control grass weed in China. Beckmannia syzigachne has evolved resistance to fenoxaprop-p-ethyl due to continuous application. To investigate fenoxaprop-p-ethyl resistant level and mechanism in B. syzigachne in a portion of the rice-wheat area in China, samples from 31 field populations were collected and treated with fenoxaprop-p-ethyl. The results show that 10 of the 31 tested field populations evolved a high level of resistance to fenoxaprop-p-ethyl. A portion of the acetyl-coenzyme A carboxylase (ACCase) gene was amplified, sequenced and aligned. The known Ile-1781-Leu, Ile-1781-Val, Ile-2041-Asn, Asp-2078-Gly and Gly-2096-Ala mutations were identified in five resistant populations. None of the known resistant substitutions was identified in the other five resistant populations, which means the resistance to fenoxaprop-p-ethyl in these populations is likely endowed by non-target-site resistance mechanism.
Keywords: ACCase, American slough grass, amino acid substitution, resistant level, resistant mechanism.
1Qingdao Agricultural University, College of Agronomy and Plant Protection, Changcheng Road 700, Qingdao, Shandong Province, China.
2Shandong Agriculture University, College of Plant Protection, Daizong Street 61, Tai’an, China.
*Corresponding author (jxwang@sdau.edu.cn).