There is described herein a mutant, non-naturally occurring or transgenic plant or part thereof having reduced expression or activity of asparagine synthetase, said asparagine synthetase comprising, consisting or consisting essentially of: (i) a polynucleotide sequence comprising, consisting or consisting essentially of a sequence having at least 90% sequence identity to SEQ ID NO:1 or at least 72% sequence identity to SEQ ID NO:3 or SEQ ID NO:5 or SEQ ID NO:7; or (ii) a polypeptide encoded by the polynucleotide set forth in (i); or (iii) a polypeptide having at least 78% sequence identity to SEQ ID NO:2 or SEQ ID NO:4 or SEQ ID NO:6 or SEQ ID NO:8; wherein the expression or activity of the asparagine synthetase set forth in (i), (ii) or (iii) is reduced as compared to a control plant.