Methods for altering levels in plants of one or more phenolic compounds that are intermediates or final products of the plant phenylpropanoid pathway are provided. One method comprises transforming a plant cell with an expression construct comprising a nucleic acid which encodes a transactivator protein comprising the myb domain of the maize "ZmMyb-IF35" protein and an activation domain. Another method comprises transforming a plant cell with an expression construct comprising a transgene which encodes an antisense ZmMyb-IF35 RNA. The present invention also relates to expression constructs and vectors used in the present methods, transformed plant cells and transgenic plants prepared according to the present methods, and the seeds of such transgenic plants.