Expression of genes related to the mechanism of resistance of Conyza sumatrensis to glyphosate

Theodoro Schneider,Magali Ferrari Grando,Anderson Luis Nunes,Mauro Antônio Rizzardi,Cássia Canzi Ceccon,Dielli Didone

doi:10.4025/actasciagron.v43i1.44824

Abstract

The elucidation of the resistance mechanism of weeds to herbicides is important for management practices. The objective of this work was to investigate the resistance mechanism of glyphosate-resistant C. sumatrensis biotypes by determining the expression levels of the constitutive gene epsps and two ABC transport protein-coding genes designated m7 and m11 with RT-qPCR. Two biotypes of C. sumatrensis were evaluated: one resistant and one susceptible to glyphosate. The treatments consisted of the absence or application of two doses of glyphosate (1,080 and 8,640 g a.e. ha-1). Plant leaves were collected at 1 and 4 days after herbicide application. No difference was observed in epsps gene expression between the studied biotypes. The expression of the m7 and m11 genes revealed that both genes had higher relative expression in the resistant biotype with the application of glyphosate at both doses. The overexpression of the m7 and m11 genes in the resistant biotype treated with glyphosate reveals that these genes play a role in herbicide resistance. These genes may be involved in the sequestration of glyphosate into the vacuole lumen in the resistant C. sumatrensis biotype studied.

Highlights

Over the last few years, agriculture has substantially contributed to the evolution of herbicide-resistant weed populations in different continents
These results suggest that the higher expression or number of copies of the epsps gene do not act as a resistance mechanism to glyphosate in this population of C. sumatrensis
Corroborating the results found in this work, the 8x dose of glyphosate applied to C. canadensis biotypes promoted a higher relative expression of the m11 gene than the 1x dose (Tani et al, 2015)

Summary

Introduction

Over the last few years, agriculture has substantially contributed to the evolution of herbicide-resistant weed populations in different continents. The extensive use of this herbicide exerts high selection pressure on various species of weeds, leading to the selection of resistant biotypes. Conyza sumatrensis is a weed species belonging to the Asteraceae family and, along with C. canadensis and C. bonariensis, is considered the most important and problematic weed for various agricultural crops (Chachalis & Travlos, 2014). In C. canadensis and C. bonariensis, the reported mechanisms of resistance to glyphosate are related to the overexpression of EPSPs, vacuole sequestration, differential translocation and metabolization (Feng et al, 2004; Ge, D’Avignon, Ackerman, & Sammons, 2010; Gonzáles-Torralva, Rojano-Delgado, Castro, Mulleder, & De Prado, 2012; Tani, Chachalis, & Travlos, 2015). The mechanism of resistance is hypothesized to be similar to that of other Conyza species

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