Extent, cause and regulation of metabolic flufenacet resistance in ryegrass (Lolium spp.)
Ryegrasses (Lolium spp.) are among the most competitive grass weeds, and their ability to rapidly develop resistance to various herbicide modes of action poses a significant challenge to modern agriculture. Originally confined to areas with intensive ryegrass cultivar cultivation, ryegrass populations are now spreading across a wider geographic range, raising concerns over their impact on crop management and herbicide efficacy.
In the laboratory of Dr Eric Patterson (Michigan State University) our research investigated the role of ryegrass cultivars in the spread of herbicide resistance. We have conducted comprehensive resistance screenings across 39 German weedy ryegrass populations, 34 commercial cultivars of the Festuca-Lolium complex available in Germany, and 18 commercial cultivars from the United States. Through this work, we identified prevalent resistance in 77% of weedy populations for ACCase inhibitors, 59% for ALS inhibitors, and 18% for VLCFA inhibitors, including flufenacet. Additionally, we assessed the ploidy levels of the weedy ryegrass populations and performed crossing experiments to understand gene flow dynamics between weeds and cultivars. One of the key findings of our study was the discovery of herbicide resistance in two German cultivars (mainly due to point mutations). Further population genetic analyses using genotyping-by-sequencing (GBS) revealed a close genetic relationship between resistant ryegrass populations and cultivars, highlighting the possibility of gene flow between cultivars and weeds under both controlled and field conditions. These results emphasize the need for caution when using ryegrass cultivars in agricultural systems, as cross-pollination could facilitate the spread of resistance.
In addition to herbicide resistance mechanisms, we have also focused on the regulation of a glutathione transferase (GST), involved in the detoxification of the herbicide flufenacet. Our RNA-Seq and gene co-expression network analysis has uncovered key genes and transcription factors potentially responsible for regulating metabolic resistance. These findings provide important insights into the complex regulatory mechanisms behind herbicide resistance evolution.
We continue to analyze the data from Göttingen, as the project GoodWeedBadWeed got approved during my stay at Michigan State University.
Project team:
- Rebecka Dücker
- Eric Patterson (Host at Michigan State University)
- Jean Wagner
