Phytotropins. IV. Effect of Phytotropins on Cultured Plant Cells and Protoplasts

Abstract

The phytotropins l-(2'-carboxyphenyl)-3-phenylpropane-1,3-dione (CPP) and 5-(2-carboxyphenyl)- 3-phenylpyrazole (CPD) reduced the net efflux of radiolabel from suspension-cultured cells treated with [¹⁴C]2,4-dichlorophenoxyacetic acid when present at concentrations comparable to those that inhibit polar transport of auxins in bean petioles. These phytotropins stimulated division of protoplasts of both Nicotiana debneyi and Petunia hybrida at concentrations of exogenous auxins that were otherwise suboptimal for divisions. The results are consistent with the proposal that phytotropins interact with specific receptors to reduce auxin efflux, resulting in increased intracellular auxin concentrations.