Differential Growth Response of Acetolactate Synthase Inhibitors-resistant Sagittaria trifolia Originated from Seeds and Tubers

WeiQiang Jia1   Sug-Won Roh2   Sung Hwan Choi3   Jong Chan Won4   Soo Yong Shim5   Jung-Sung Chung6   Le Thi Hien1   Aung Bo Bo1   Kee Woong Park1,*   Jeung Joo Lee4,*   

1Department of Crop Science, Chungnam National University, Daejeon 34134, Korea
2Rural Development Administration Food Crop Industry Technology Service Division, Jeonju 54875, Korea
3Department of Horticulture, Gyeongnam National University of Science and Technology, Jinju 52725, Korea
4Department of Plant Medicine, IALS, Gyeongsang National University, Jinju 52828, Korea
5Division of Applied Life Science (BK21 Plus), Gyeongsang National University, Jinju 52828, Korea
6Institute of Agriculture and Life Science (IALS), Gyeongsang National University, Jinju 52828, Korea


Continuous use of acetolactate synthase (ALS) inhibitors has led to the selection of herbicide-resistant Sagittaria trifolia in paddy fields. Herbicide-resistant (R) S. trifolia was first reported in 2011 in Korea. The objective of this study was to investigate the level and mechanism of resistance and understand the fitness of R biotypes using R and susceptible (S) S. trifolia biotypes originated from seeds and tubers. Whole plant dose-response showed that the R biotypes originated from tubers were highly resistant to cyclosulfamuron and moderately resistant to penoxsulam and imazaquin, with R/S ratios of 250, 13 and 8, respectively. Compared to the S biotype, the R biotype originated from tuber had an amino acid substitution at the position of a Pro197-Leu residue of als gene, a well-known mutation site that could confer resistance to sulfonylurea, triazolopyrimidine, and imidazolinone herbicides. Additionally, the germination rate and growth of the S biotypes originated from seeds were lower than those of the R biotypes. The growth of the S biotypes originated from tubers was more vigorous than that of the R biotypes. Once the seed of R biotypes move to uninfected paddy fields, the germination rate of R biotypes is probably more than that of existing S biotypes. If ALS inhibitors are applied into paddy fields, R biotypes can survive and even produce tubers that can continually propagate and probably become dominant in the population in uninfected paddy fields. Thus, increasing the application rate of ALS inhibitors to kill R biotypes probably can enhance ALS-inhibitors’ selection-pressure.

Figures & Tables

Fig. 1. Dose-response of biotypes (○: susceptible, ●: resistant) to three acetolactate synthase (ALS) inhibitors (cyclosulfamuron, penoxsulam, and imazaquin).