Expression and function analysis of the metallothionein-like (MT-like) gene from Festuca rubra in Chlamydomonas reinhardtii chloroplast.

The cDNA of the metallothionein-like (MT-like) gene from Festuca rubra cv. Merlin was optimized with bias codon of Chlamydomonas reinhardtii chloroplast genome. The optimized MT-like gene was delivered into C. reinhardtii chloroplast and the transgenic strains expressing MT-like gene was obtained. PCR-Southern blot and RT-PCR-Southern blot analysis demonstrated that the MT-like gene was integrated into chloroplast genome of C. reinhardtii and expressed at the transcriptional level. The cadmium binding capacity of the transgenic C. reinhardtii was determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) and the binding properties were analyzed. Results showed that the transgenic C. reinhardtii expressing the MT-like gene exhibited remarkably higher Cd(2+) binding capacity and grew to higher densities at toxic Cd(2+) concentrations (40-100 micromol/L) than the wild type strain, and that the IC(50) of Cd(2+) (3-d treating) to algal cell growth of transgenic strain was 55.43% higher than that of the wild type strain, indicating that the Cd(2+) binding capacity and Cd(2+) tolerance of C. reinhardtii was enhanced through the expression of the foreign MT-like gene in chloroplast.