Abstract
Auxin responses are mainly mediated by three molecules, AUX/IAA, auxin receptor, Tir1 and transcription factor, ARFs. Gravitropism and phototropism of Arabidopsis hypocotyls are mediated by ARF7 and IAA19 (Tatematsu et al., 2004, Watahiki and Yamamoto., 1996). Initial action of auxin ignites degradation of IAA19 protein and induces early-auxin-inducible genes. Although the monitoring the level of IAA19 protein is important for the understanding of molecular mechanisms of auxin action, the native or GFP-fused IAA19 protein were barely detectable. However combination of ultra-sensitive CCD camera and new luciferase gene fusion enabled not only monitoring IAA19 promoter activity, but IAA19 fusion protein. We report here that a spatial and temporal action of auxin during Arabidopsis morphogenesis.
