Weed resistance diagnostic technologies to detect herbicide resistance in cerealgrowing areas. A review

Cereals are major crops used for food and feed. By 2050, the world population is expected to be close to 10 billion requiring a doubling of the food production from a fixed area of arable land. The control of weeds in cropping systems is one key step to optimize yield. In the last several decades, herbicides have become the most effective management tool for adequate weed control. However, their repetitive use, as well as the limited number of modes of action (MoA) available, has led to the development of resistance in weeds. It has become imperative to change practices that lead to the development of weed resistance in order to protect those MoAs which are still effective in cereals. Several mechanisms of resistance have been developed by weeds to survive herbicide applications. Among them, gene mutations reducing or inhibiting herbicide binding by conferring amino-acid changes in a target enzyme (Target Site Resistance, TSR) and detoxification of the herbicide (Enhanced Metabolic Resistance, EMR) are the main mechanisms in key grass weeds found in cereal crops. These two mechanisms have been extensively studied during the last years and, thus, enabled the development of analytical tools for resistance diagnosis. Sustainable strategies for weed management using herbicides rely on accurate resistance diagnostics that permit optimization of treatment solutions that will lead to herbicide longevity. Greenhouse and laboratory tests used for resistance diagnosis will be reviewed with an emphasis on biochemical and molecular biology technologies. Cases of resistance to ACCase inhibitor herbicides will be presented as examples. Finally, the future development of these technologies will be discussed in the perspective of more practical uses.