Abstract:

The DII auxin sensor has been an invaluable tool for mapping the spatiotemporal auxin response and distribution in the model plant Arabidopsis thaliana. The DII sensor and the mDII control sensor are driven by the widely used constitutive 35S promoter. Recently, however, the reliability of the DII sensor has been questioned (Bhatia et al. 2019). They argued that the 35S promoter activity is biased toward leaf primordium adaxial side that face the shoot apical meristem (SAM). Here, we provide additional evidence to show that the mDII control sensor is indeed uniformly distributed in early leaf primordia, in agreement with the original reports (Vernoux et al. 2011; Brunoud et al. 2012). We used the DII/mDII and RPS5A promoter‐driven R2D2 sensors to confirm the presence of asymmetric auxin signaling in early leaf primordia. In addition to these analyses, we show that the imaging data reported by Bhatia et al. (2019) may suffer from artefacts, and that their analysis was artificially biased due to an arbitrary domain demarcation.