The present invention provides compositions and methods for regulating expression of heterologous nucleotide sequences in a plant. Compositions include a novel nucleotide sequence for a root-preferred promoter for the gene encoding Cyclo1. A method for expressing a heterologous nucleotide sequence in a plant using the promoter sequences disclosed herein is provided. The method comprises stabling incorporating into the genome of a plant cell a nucleotide sequence operably linked to the root-preferred promoter of the present invention and regenerating a stably transformed plant that expresses the nucleotide sequence. The present invention also relates to isolated nucleic acids encoding plant cyclotides. The invention relates to the construction of a chimeric gene encoding all or a portion of the plant cyclotides, in sense or antisense orientation, wherein expression of the chimeric gene results in the production of altered levels of plant cyclotides in a transformed host cell.