CYP72A1182 is involved in metabolic resistance evolution to tembotrione in Palmer amaranth

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 analyzed. We performed QTL mapping to identify genomic regions associated with resistance. CYP72A1182 deactivated tembotrione. This gene had increased expression in other A. palmeri populations resistant to multiple herbicides, including-tembotrione. Resistant plants exhibited polymorphisms in the promoter of CYP72A1182. We identified QTLs linked to herbicide resistance, including one on chromosome 4 approximately 3 Mb away from CYP72A1182. CYP72A1182 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; however further studies are in progress to test this hypothesis. The elucidation of regulatory genes is crucial for developing innovative weed management approaches and target-based novel molecules. Pseudo-F2 plants were generated by crossing HPPD-resistant population of Plamer amaranth (NER) and susceptible (NES). Six most susceptible and 6 most resistance were used for gene expression analysis. Time-points analyzed were 0, 6 and 12 h after tembotrione application. Plants from two crosses were used for analysis, cross 4 and cross 5. The total samples are 72.