eLife Assessment
This valuable study concerns a highly interesting and biologically relevant topic, the regulation of the PIN auxin transporter, which is of broad interest to the plant biology community. The authors propose NPY1 to act downstream of PID in auxin-mediated development by modulating PIN phosphorylation, which, if experimentally solidified, would expand our understanding of PIN regulation. While the genetic evidence is solid, the mechanistic role of NPY1 and the functional relevance of phosphorylated PIN residues are still uncertain. There are also concerns regarding experimental rigor and methodological transparency.