Abstract
Degradation of the Aux/IAA proteins has been recently found to be the primary reaction of auxin response that is mediated through the auxin receptors. To better understand the degradation of Aux/IAA in the context of physiological responses of auxin, we have conducted measurements of half lives of luciferase (LUC) fused with IAA17/AXR3 or IAA19/MSG2 expressed constitutively by 35S promoter in Arabidopsis. When cycloheximide was added to the transgenic seedlings grown hydroponically for 4 - 5 days in the dark, luminescence decreased rapidly, from whose kinetics half life was determined. When LUC was not fused to any Aux/IAA proteins, its half life was longer than 60 min. In contrast, half life of IAA17- and IAA19-LUC was about 10 and 15 min respectively. Rapid degradation of IAA17 has been reported by Dreher et al. (2006). Our results showed that IAA19 was also degraded as readily as IAA17.
