Abstract
Previously tissue specificity of MSG2/IAA19 gene expression was examined by northern blot hybridization or MSG2 promoter-GUS reporter (Tatematsu et al., 2004). In the present study, firefly luciferase (LUC) was employed for the live tissue imaging of the MSG2 promoter activity as well as the MSG2 protein level. The 3 kb-long MSG2 promoter fusion of LUC gene was stably introduced into Arabidopsis plants. An ultra-sensitive camera system revealed the luciferase images of hypocotyls which were similar to those of promoter-GUS and showed transient auxin induction of the LUC signals. Hypocotyls expressing the MSG2-LUC fusion protein showed much weaker signals than those of the promoter fusion. Signals of the protein fusion with the mutant msg2 protein were stronger than those with the wild-type protein. Auxin treatment transiently increased signals from both of the fusion proteins. We showed, for the first time, spatial and temporal expression of Aux/IAA genes in living plants.
