Molecular and physiological bases of glyphosate weed resistance: current status and future perspectives

In the present key lecture a general overview of molecular and physiological bases of glyphosate weed resistance will be shown. A dramatic increase in the frequency and diversity of herbicide-resistant weed biotypes over the past two decades has occurred. Weed resistance poses a threat to the sustainability of agriculture at both local and global levels. When reviewed a decade ago, there were no cases of evolved glyphosate resistance, despite 20 yr of use. Most of the reported cases of glyphosate resistance are linked to Roundup Ready (RR) crops. In particular, the trend of glyphosate weed resistant biotype in RR crops is really worrying. After a detailed analysis of the available literature, glyphosate is not prone in developing resistance phenomena when it is used as a not selective herbicide. However, when it is used as selective herbicide in RR crops, the selection pressure exerted is relevant and can strongly promote the selection of resistant weed biotypes.