Arabidopsis PROTEIN S-ACYL TRANSFERASE4 mediates root hair growth angle and morphology

Plants absorb water and nutrients from the soil through their root systems, with root hair cells playing a critical role in this process. Root hair growth is regulated not only by genetic factors but also by environmental cues. Current descriptions of root hair phenotypes primarily focus on root hair density and length. Our previous studies have shown that PAT4 regulates root hair elongation by mediating the plasma membrane localization of ROP2. In this study, we found that loss of PAT4 function leads to a smaller angle between root hairs and the primary root plane, accompanied by abnormal root hair morphology, including branching, upturning, and basal swelling. Conversely, PAT4 overexpression resulted in a significant increase in the root hair growth angle compared to wild-type plants. Exogenous application of auxin exacerbated the morphological abnormalities of root hairs in pat4 mutants. Genetic analysis revealed an additive effect between myosin XIK and PAT4 in regulating root hair elongation. Additionally, although PAT16 is expressed in root hairs and its protein localizes to the Golgi apparatus, phenotypic analysis showed that PAT16 does not participate in root hair growth regulation. Collectively, these findings demonstrate that PAT4 is involved in regulating root hair morphogenesis. Moreover, root hair growth angle provides a new dimension for phenotypic analysis of root hairs.