Cloning of PCS gene (TpPCS1) from Tagetes patula L. and Expression analysis under Cadmium Stress.

Phytochelatins (PCs) is an important mechanism for plants to resist heavy metal stress. Widely found in higher plants, small heavy metal binding peptides, synthesized under the catalysis of phytochelatin synthase (PCS); the process involves the metal ion sequestration, detoxification and transportation of metal in plants. Peacock grass (Tagetes patula L.), a species of annual herbage of Asteraceae, is characterized with rich in heavy metal, especially with strong cadmium resistance. Through rapid amplification of cDNA ends (RACE) technology, the full-length cDNA sequence of PCS gene is obtained from Tagetes patula L. Meanwhile, the relative expression of TpPCS1 gene under different concentrations of cadmium (Cd) stress is analyzed by quantitative real-time polymerase Chain Reaction (qRT-PCR). Results obtained under cadmium stress are as follow: ORF analysis show a gene length of 1970bp, a gene coding area length of 1764bp and the coding of 587 amino acids. The expression of TpPCS1 gene has tissue specificity, the expression of different growth periods varies from organ to organ, the TpPCS1 gene in the root showed higher expression, the expression of the TpPCS1 gene in the leaf and seed was relatively low, with the increase of cadmium stress concentration and the increase of stress time, the expression of TpPCS1 gene in plant roots, stems and leaves showed an upward trend. This research shows that the TpPCS1 gene coding protein gives peacock grass great the ability to transport heavy metal cadmium, which can be used to construct plant hyperexpression carrier to provide new ideas for plant restoration technology.