Arabinogalactan protein motif-containing receptor-like kinases are likely to play the negative feedback factor to maintain proper root hair length.

Coordination of the events between cytoplasm and cell wall is necessary for the proper cellular activity of plants. Cell wall-associated receptor kinases are likely to play the interface for the extra-to-internal signaling process. Arabidopsis ROOT HAIR SPECIFIC 10 (RHS10), belonging to the proline-rich extensin-like receptor kinase (PERK) family, is a Ser/Thr protein kinase with arabinogalactan protein (AGP) motifs in its extracellular domain (ECD). RHS10 and other angiosperm PERK homologs are inhibitory in root hair tip growth. The ECD deletion analysis of RHS10 indicates that proline residues, including AGP motifs, in the ECD are required for the root hair inhibition. The kinase domain of RHS10 physically interacts with an RNase (RNS2), and both RHS10 and RNS2 show the consistent genetic interaction in terms of root hair phenotype and root RNA levels. The root hair-inhibitory function of the cell wall-associated receptor kinase RHS10 may provide a negative feedback tool between cell wall and cytoplasm for the determination of proper length of the root hair.