The multidrug and toxin extrusion ( <scp>MATE</scp> ) transporter <scp>DTX51</scp> antagonizes non‐cell‐autonomous <scp>HLS1</scp> – <scp>AMP1</scp> signaling in a region‐specific manner

Multidrug and toxin extrusion (MATE) transporters are widely conserved across all domains of life and play diverse roles in plant development. Here, we investigated the role of DETOXIFICATION 51 (DTX51), a MATE transporter in Arabidopsis. Overexpression of DTX51 led to pleiotropic phenotypes resembling those of hls1 hlh1 and amp1 lamp1 loss-of-function mutants, which have disruptions of key developmental regulators that act non-cell-autonomously. Genetic and gene expression analyses revealed that DTX51 and HLS1 act within the same genetic pathway, forming a negative feedback loop at the transcriptional level. Spatially restricted overexpression experiments showed that, in contrast to HLS1 and AMP1, DTX51 acts in a region-specific manner within the shoot apical meristem, suggesting that DTX51 fine-tunes development locally by modulating non-cell-autonomous signals. Impact statement This study reveals a role of the MATE transporter DTX51, whose transport substrate remains unknown, in Arabidopsis development, providing new insights into how this transporter fine-tunes non-cell-autonomous signals generated by the HLS1-AMP1 module.