The Resistance Levels and Target-Site Based Resistance Mechanisms to Glyphosate in Eleusine indica from China

Abstract

The Dongting and Poyang Lakes are the important rice growing areas, and the Bohai Rim and Loess Plateau are the main producing areas of apples in China, where glyphosate has been used continuously to control weeds including Eleusine. indica for many years. In this study, the resistance levels and target-site based resistance (TSR) mechanisms to glyphosate in E. indica populations, which were collected from above areas were investigated. A total of 35 out of 50 (70%) E. indica populations have evolved resistance to glyphosate with resistance index (RI) of 2.01~10.43. The glyphosate-resistant (GR) E. indica accumulated less shikimic acid than glyphosate-susceptible (GS) populations, when treated by 1.0 mg/L, 10 mg/L or 100 mg/L glyphosate. There was no mutation at Thr102 and Pro106 in 5-enolpyruvate shikimate-3-phosphate synthase (EPSPS), which endowed glyphosate resistance in E. indica and other weed species. A Pro-381-Leu was found in EPSPS in GR populations. In contrast, the expression level of EPSPS gene was highly correlated with glyphosate resistance in E. indica with a Pearson coefficient of 0.73. These indicate that the glyphosate resistance in aforementioned E. indica populations was mainly caused by the overexpression of EPSPS, not by amino acid mutation in EPSPS.

Advances in molecular plant pathology, plant abiotic and biotic stress

“…Previously, many studies have demonstrated that silencing of NbHSP90 in N. benthamiana will lead to the reduction of PR gene expression level and promote the infection of potato virus X (PVX), P. syringae and TMV (Sangster and Queitsch, 2005). In contrast, a recent study indicated that silencing the homologous gene of potato StHSP90.5 in N. benthamiana reduced PVY accumulation and induced defense-related gene expression (Li et al, 2022). Silencing NbHSP90 gene in N. benthamiana could inhibit Ralstonia solanacearum infection by inducing PR gene expression (Ito et al, 2015).…”

“…During the last decade, red stripe outbreaks occurred in two main sugarcanegrowing provinces in China. In the Guangxi province, disease incidences in the field reached 23% in variety FN38 (Fu et al, 2017), 39% in BT15-173 , 50% in GT58, and 22% in LC05-136 (Li et al, 2022). In the Yunnan province, 80% of plants of variety YZ03-194 were symptomatic (Shan et al, 2017).…”

“…South China is one of the first areas in China to control weeds with glyphosate (Yang et al, 2012). Similar to other countries, the long-term application of glyphosate has resulted in development of glyphosate resistance in some weed species in China (Song et al, 2011;Zhang et al, 2015a;Li et al, 2022), especially in E. indica. Considering that paraquat use has been banned and the extent of glyphosate-resistant crops may increase significantly in the near future, it is likely that glyphosate will continue to play an important role in the nonselective herbicide market in China for the foreseeable future .…”

Temperature influences glyphosate efficacy on glyphosate-resistant and -susceptible goosegrass (Eleusine indica)

“…South China is one of the first areas in China to control weeds with glyphosate ( Yang et al., 2012 ). Similar to other countries, the long-term application of glyphosate has resulted in development of glyphosate resistance in some weed species in China ( Song et al., 2011 ; Chen et al., 2015 ; Zhang et al., 2015a ; Deng et al., 2020 ; Li et al., 2022 ), especially in E. indica . Considering that paraquat use has been banned and the extent of glyphosate-resistant crops may increase significantly in the near future, it is likely that glyphosate will continue to play an important role in the nonselective herbicide market in China for the foreseeable future ( Liu et al., 2021 ; Zhang et al., 2022 ).…”

Subtelomeric 5-enolpyruvylshikimate-3-phosphate synthase copy number variation confers glyphosate resistance in Eleusine indica

“…Glyphosate is a non-selective herbicide that targets the protein 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) 1 , an essential enzyme for aromatic amino acid synthesis in plants. In some cases, glyphosate resistance in goosegrass is caused by EPSPS target site mutations, such as the Pro106 single mutations and the Thr102Ile and Pro106Ser (i.e., TIPS) double mutation 2 ; however, increased EPSPS copy number variation (CNV) 3 , a type of genomic structural variation (SV), is the more frequent mechanism 3 in this species. With both mechanisms present in goosegrass, some populations, or even individuals, can have both EPSPS CNV and target-site mutations 4 , with some, most, or all the copies of EPSPS having one or multiple mutations.…”