Researchers Find Herbicide Resistance in Blackgrass Caused by Pre-existing Genetic Variation

A team led by researchers of the Max Planck Institute for Biology Tübingen and the University of Hohenheim in Stuttgart has found that resistance to herbicides is mostly attributed to genetic variants predating the use of herbicides.

In Europe, blackgrass has become the most economically damaging herbicide-resistant weed. Farmers all over Europe face an increasingly difficult battle against blackgrass. The team of scientists led by Detlef Weigel (Max Planck Institute for Biology Tübingen) and Karl Schmid (University of Hohenheim) studied the evolutionary mechanisms of how resistances arise. The two most common herbicides that have been used against blackgrass impede the activity of either one of two proteins, which are both vital for the weed to thrive.

The researchers generated a reference genome of blackgrass and analyzed the genetic structure of resistant populations. The team found that variation in most resistant populations indicates that the spread of the resistances is the result of pre-existing gene variants, and only to a lesser degree of spontaneous mutations. The researchers then compared their empirical data with simulations of different scenarios for adaptation, confirming that the target-site resistance variants were likely present already before herbicides started to exert selective pressure.

For more details, read the news article in the Max-Planck Society's Newsroom.