Abstract: Phytoene synthase (Psy) gene , a primary rate-limiting enzyme in the biosynthesis pathway of wheat yellow pigment (YP) , was cloned and sequenced in this study , at the same time , the Psy gene sequences between wheat and maize were compared . The results showed that, a 1 192 bp DNA fragment was amplified by polymerase chain reaction in DNA
samples extracted from the high YP and low YP content wheat cultivar , the gene fragment contains a intact exon of Psy gene, which codes 78 amino acids . Sequence analysis showed that the wheat DNA fragment was closely homologous to those of the maize 4th exon, with homology rate of nucleotide and amino acids sequences at 80 . 74% and 85 .89% . Although there were 47 SNPs in the homology area of wheat and maize, only 11 SNPs led to the variation of amino acid sequences, which indicates Psy gene was, conservative in different species. Blast clustering analysis showed , the class of Psy gene was significantly related to their genetic relationship in gramineous plants, the Psy gene of wheat was more advanced than other cereal plants in system evolution .

Key words: Wheat