A method is disclosed for reducing the level of gossypol in cottonseed. The method generally includes selectively inducing RNA gene silencing in the seed of a transgenic cotton plant, to interfere with expression of the δ-cadinene synthase gene or the δ-cadinene-8-hydroxylase gene in the seed of the cotton plant without substantially affecting expression of that gene in the foliage, floral parts, and roots of the plant. The transgenic cotton plant comprises at least one of a δ-cadinene synthase gene trigger sequence and/or a δ-cadinene-8-hydroxylase gene trigger sequence operably linked to one or more a seed-specific promoter gene sequences, and the trigger sequence(s) is/are able to induce RNA gene silencing when expressed in cottonseed of the plant. Also disclosed are expression cassettes, vectors, cells, seeds, and plants containing at least one of a δ-cadinene synthase gene trigger sequence and/or a δ-cadinene-8-hydroxylase gene trigger sequence operably linked to one ore more a seed-specific promoter DNA sequences.