Prephenate dehydrogenases and arogenate dehydrogenase polynucleotide and polypeptide sequences are provided herein. These polypeptides are all insensitive to effector based feedback inhibition. Polypeptides with these activities and lacking feedback inhibition by the product were not previously identified and characterized from plants. The polypeptides may be used to generate constructs and transgenic cells or plants. Methods of increasing production of products of the tyrosine or HPP pathway by increasing expression of the polynucleotides provided herein in plants or cells overexpressing the polypeptides are provided. In addition overexpression of the polypeptides in plant cells increases resistance to herbicides.