Glyphosate resistance in barnyard grass (Echinochloa colona)

Abstract

Echinochloa colona is an important summer-growing weed species in northern Australian cropping regions. As a result of the intensive use of glyphosate in summer fallows, glyphosate resistant populations of E. colona have evolved, with the number of resistant populations identified rapidly growing. This study identified glyphosate resistance in E. colona collected from different locations in Australia and investigated the mechanism of glyphosate resistance. Pot trials conducted on populations ofE. colona collected from northern Australia identified resistance to glyphosate in 11 populations of this weed species. The level of resistance varied among the populations from 2- to 11-fold. Sequencing of the target-site (EPSPS) identified a mutation at position 106 leading to a change from proline to serine in the most resistant population A533.1 only. With the range of resistance levels identified, it is expected that different mechanisms of resistance will be present among the rest of the resistant populations.