EPSPS duplication and mutation involved in glyphosate resistance in the allotetraploid weed species Poa annua L.

Background: Poa annua is a widespread winter annual weed species in California. Recently, poor control of this species with glyphosate was reported by growers in an almond orchard in California with a history of repetitive glyphosate use. The objectives of this research were to evaluate the level of glyphosate resistance in a developed S P.

Multiple target site resistance to glyphosate in junglerice (Echinochloa colona) lines from California orchards.

Background: In California specialty cropping systems such as vineyards and orchards, Echinochloa colona is present as a summer annual weed. It is able to germinate throughout the growing season whenever favorable conditions are present, and management relies heavily on glyphosate applications. Glyphosate-resistant (GR) E.

Transcription of putative tonoplast transporters in response to glyphosate and paraquat stress in Conyza bonariensis and Conyza canadensis and selection of reference genes for qRT-PCR.

Herbicide resistance is a challenge for modern agriculture further complicated by cases of resistance to multiple herbicides. Conyza bonariensis and Conyza canadensis are invasive weeds of field crops, orchards, and non-cropped areas in many parts of the world. In California, USA, Conyza populations resistant to the herbicides glyphosate and paraquat have recently been described.

Glyphosate resistance in Ambrosia trifida: Part 2. Rapid response physiology and non-target-site resistance.

Background: The glyphosate-resistant rapid response (GR RR) resistance mechanism in Ambrosia trifida is not due to target-site resistance (TSR) mechanisms. This study explores the physiology of the rapid response and the possibility of reduced translocation and vacuolar sequestration as non-target-site resistance (NTSR) mechanisms.

Results: GR RR leaf discs accumulated hydrogen peroxide within minutes of glyphosate exposure, but only in mature leaf tissue.

Glyphosate resistance in Ambrosia trifida: Part 1. Novel rapid cell death response to glyphosate.

Background: Glyphosate-resistant (GR) Ambrosia trifida is now present in the midwestern United States and in southwestern Ontario, Canada. Two distinct GR phenotypes are known, including a rapid response (GR RR) phenotype, which exhibits cell death within hours after treatment, and a non-rapid response (GR NRR) phenotype. The mechanisms of resistance in both GR RR and GR NRR remain unknown.