Arabidopsis cationic amino acid transporter (CAT) is a high affinity transporter for a systemic herbicide L-Phosphinothricin
L-phosphinothricin (PPT) is a broad-spectrum herbicide, however its transportation mechanisms remain unidentified. Here we present cationic amino acid transporters (CAT) as the high affinity transporter of PPT, explaining the different sensitivities of flowering and non-flowering plants. Comparative analysis between Arabidopsis thaliana and Marchantia polymorpha revealed non-target site mechanisms for PPT resistance in the latter. LC-MS analysis showed minimal PPT uptake by M. polymorpha, while transcriptomic analysis identified four candidate transporters for PPT uptake. Overexpression of AtCAT1 and AtCAT5 in M. polymorpha increased PPT susceptibility and uptake. Protein molecular dynamics simulation revealed the modes of PPT transportation, allowing for mutagenesis strategies to reduce PPT susceptibility. This study reports the first high affinity PPT transporter, AtCAT, and highlights the natural diversity of PPT susceptibility due to transportation. Overall design: To identify transcriptional response to GS-inhibiting herbicides, RNAseq analysis was perform on Arabidopsis seedlings and Marchantia gemmalings treated with glutamine, phosphinothricin, or methionine sulfoxime for 48h. Untreated plants were used as controls. n=3