CYTOCHROME P450 CYP72A219 IS INVOLVED IN EVOLUTION OF METABOLIC RESISTANCE TO TEMBOTRIONE IN Amaranthus palmeri POPULATIONS

Evolution of metabolic herbicide resistance is a major issue for weed management. Few genes and regulatory mechanisms have been identified, particularly in dicotyledonous weed species. We identified putative causal genes and regulatory mechanism for tembotrione-resistance in Amaranthus palmeri. Cytochrome P450 candidate genes were identified through RNA-seq analysis. We validated their functions using heterologous expression in S. cerevisae. Promoters of the candidate P450 genes were tested in transient expression assays. We performed QTL mapping to identify genomic regions associated with resistance. CYP72A219\_4284 deactivated tembotrione. This gene had increased expression in other A. palmeri populations resistant to multiple herbicides, including-tembotrione. A promoter allele of CYP72A219\_4284 from resistant individuals caused increased reporter gene expression. We identified QTLs linked to herbicide resistance, including one on chromosome 4 approximately 3 Mb away from CYP72A219\_4284. CYP72A219\_4284 is involved in tembotrione resistance in A. palmeri. Increased expression of this gene could be due to cis-regulation in the promoter, as well as trans-regulation from transcription factors. The elucidation of regulatory genes is crucial for developing innovative weed management approaches and target-based novel molecules. ### Competing Interest Statement The authors have declared no competing interest.