Overexpression of Arabidopsis Wali7 Domain-Containing Protein ASR Produces Auxin-Mediated Short-Root Phenotype

Wali7 domain-containing protein has been isolated from roots and root hairs. However, the function of this protein has not been reported yet. This study demonstrated that overexpression of a gene encoding Arabidopsis Wali7 domain-containing protein, called auxin-mediated short root (ASR), produced a short-root phenotype. Expression analysis indicated that ASR was induced by auxin. ASR overexpression resulted in a lower level of auxin in transgenic plant roots as indicated by lower DR5::b-glucuronidase (GUS) activity and lower expressions of genes encoding the rate-limited enzymes of auxin synthesis. Our results also suggested that ASR overexpression caused decreased meristematic activity and impaired stem cell division as indicated by CycB1:1::GUS activity and lower expression of a plethora of stem cell transcription factors, respectively. In addition, exogenous application of auxin (NAA and indole-3-acetic acid) could repair root development defects. ASR overexpression decreased auxin levels in transgenic Arabidopsis roots, caused decreased meristematic activity and impaired stem cell division, and resulted in a short-root phenotype.