EPSPS gene amplification conferring resistance to glyphosate in windmill grass (Chloris truncata) in Australia

Abstract

This study has identified EPSPS gene amplification contributing to glyphosate resistance in C. truncata. In addition, a Glu-91-Ala mutation within EPSPS was identified that may contribute to glyphosate resistance in this species. © 2017 Society of Chemical Industry.

EPSPS gene amplification confers resistance to glyphosate resistant populations of Hordeum glaucum Stued (northern barley grass) in South Australia

“…EPSPS gene amplification is becoming a common glyphosate resistance mechanism identified in weed populations from situations where glyphosate is applied intensively, such as transgenic crops and other crop situations . The majority of examples of EPSPS gene amplification were reported from the USA and a few from Australia . This mechanism usually provides a higher level of glyphosate resistance compared with target site mutations.…”

“…The selection intensity imposed by a single annual application is lower than situations where several applications may occur each year but is still sufficient to select for resistance. However, the gene copy numbers identified in these populations are lower than reported in other species such as A. palmeri with 5 to > 160 gene copy numbers, Bromus diandrus up to 25 copy numbers and Chloris truncata with 16–25 copy numbers . There is not always a clear relationship between EPSPS copy number and the level of glyphosate resistance .…”

“…Glyphosate inhibits the enzyme EPSPS in the shikimic pathway of plants, which leads to massive accumulation of shikimate . As reported in several previous studies, glyphosate‐resistant weeds tend to accumulate less shikimate compared with susceptible populations . According to Shaner et al ., if shikimate accumulation in a glyphosate‐susceptible population is higher than the resistant populations at both low and high rates of glyphosate, it indicates that the resistant population likely contains a target site mechanism (gene mutation or amplification) or an unknown mechanism.…”

“…Shikimate accumulation in leaves was assessed following the methods of Ngo et al . with some modifications.…”

Alterations in the 5′ untranslated region of the 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) gene influence EPSPS overexpression in glyphosate‐resistant Eleusine indica

“…The sequential evolution of a double amino acid substitution [T102I + P106S (TIPS)] mutation, resulting in high glyphosate resistance, has also been documented in E. indica . Overexpression of EPSPS as a result of gene amplification has been reported in seven glyphosate‐resistant weed species . However, EPSPS amplification may not be the only factor that leads to up‐regulation of EPSPS expression and thus may not fully explain glyphosate resistance.…”