Subcellular Trafficking of Plant Secondary Metabolites Lin, Y. and E. Grotewold Department of Plant Biology and Plant Biotechnology Center, The Ohio State University, Columbus Ohio. We have used flavonoid biosynthesis as a model system to investigate plant metabolic pathways and the mechanisms by which plants control gene expression. In maize, two branches of flavonoid biosynthesis are independently regulated by the Myb-domain proteins P and C1, providing one of the best understood regulatory networks in plants. The analysis of the compounds induced by the ectopic expression of these Myb factors indicated that they play novel regulatory functions, not obvious from previous studies. Autofluorescent compounds induced by P provide unique markers to investigate trafficking and subcellular localization of secondary metabolites.
P induces the accumulation of two fluorescent compounds targeted to distinct subcellular structures.
A yellow fluorescent compound accumulates in discrete bodies within the vacuolar compartment. Bodies filled with a green fluorescent compound accumulate, upon P induction, in the cytoplasm of BMS cells. These bodies move to the cell surface, fuse with the cell membrane, and release the green fluorescent compound to the cell wall. Rather, the number of cells with green fluorescent bodies and green fluorescence in the cell wall increases. In contrast, the transport of the yellow fluorescent compound to the vacuole is not affected by these treatments.