Distribution and genetic diversity of Echinochloa oryzicola resistant to ALS and ACCase inhibitors in Korea

Abstract

The emerging incidence of herbicide resistance in weeds is a serious problem for rice production in Korea. Echinochloa oryzicola has been reported as multiple resistant to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibitors. The objectives of this study were to monitor distribution and genetic diversity of E. oryzicola suspected to have herbicide resistance to ALS and ACCase inhibitors in Korean paddy fields by using simple sequence repeat (SSR) marker. The occurrence and propagation of herbicide-resistant E. oryzicola were found at serious levels in Jeonbuk and Chungnam provinces. The worst affected regions were Gimje, Gunsan, and Iksan of Jeonbuk province. Herbicide resistance levels of E. oryzicola populations to ALS inhibitors were much greater than those to ACCase inhibitors. SSR analysis showed very low genetic differentiation between ALS and ACCase on resistance and susceptibility. While genetic diversity has been confirmed by province scale, herbicide-resistant E. oryzicola was found to be spreading severely throughout Korea. Thus, it is necessary to monitor herbicide resistance regularly and develop a long-term strategy of integrated pest management for infested paddy fields.