Isolation and expression analysis of aspartokinase gene fragment from Carthamus tinctorius Molecular cloning, sequence analysis, and construction of expression vector of monofunction feedback inhibition sensitive CtAK1 gene in Carthamus tinctorius The effects of three cultivation methods on amino acid content of rice grains and preliminary study on its mechanism Selection and Characterization of Maize Variants Resistant to S-(2-Aminoethyl)-L-Cysteine and 5-Methyltryptophan