Nucleotide sequences encoding anthranilate synthase

A 5-methyltryptophan resistant Nicotiana anthranilate synthase genes are disclosed, in particular the ASA2 gene of Nicotiana tabacum. Constructs containing the genes are also disclosed. This genes are useful for transforming plant cells and producing transformed plants and progenies which, compared to untransformed plant cells and plants, are more resistant to tryptophan analogs and/or produce increased levels of tryptophan. The transformed seeds are also disclosed. The genes are also useful as selectable markers. The amino acid sequence of ASA2, purified ASA2, and recombinant ASA2 are also disclosed.