Production of high tryptophan maize by chloroplast targeted expression of anthranilate synthase

An expression vector comprising a polynucleotide molecule encoding a chloroplast transit peptide fused to a monomeric anthranilate synthase, wherein the chloroplast transit peptide is heterologous to the monomeric anthranilate synthase, wherein:

• a) the chloroplast transit peptide comprises the polypeptide sequence of SEQ ID NO:
• 28;
• or
• b) the polynucleotide molecule encoding the chloroplast transit peptide comprises SEQ ID NO:
• 9;
• wherein said chloroplast transit peptide provides enhanced targeting of said monomeric anthranilate synthase to a chloroplast of a plant cell when compared to the targeting of said anthranilate synthase by chloroplast transit peptide 1 (CTP1) of SEQ ID NO:19;
• wherein said polynucleotide molecule provides enhanced levels of at least tryptophan in a transgenic plant cell comprising said polynucleotide molecule when compared to a plant cell of the same genotype but lacking said polynucleotide molecule;
• and wherein said monomeric anthranilate synthase is feedback insensitive to tryptophan.