Preliminary Identification Of CrGNAT Regulating Tolerance Of Chlamydomonas Reinhardtii To Copper Toxicity

With the development of society, heavy metals have become environmental pollutants, especially for the pollution to water, which has become a global issue. With a certain effect, utilizing algae to repair and purify water polluted by heavy metals has drawn much attention. Studies on the mechanism for heavy metal pollution by algae and generating transgenic algae lines with high tolerance and metal enrichment have become the focus of significant biology research.Histone acetylation can influence transcriptional expression activity of genes and play a important role as a signal inducing incorporation between transcription factors and in the regulation of gene transcription. In the thesis, we identified the gene CrGNAT, which belongs to a subfamily of histone acetyltransferases, whose function is unclear.To explore the function of CrGNAT, we cloned the full length gene from Chlamydomonas reinhardtii and constructed a CrGNAT overexpressing algae (35S::CrGNAT) and a 35S::Anti-CrGNAT anti-expressing algae. Through the glass bead transformation method, we successfully obtained two lines of transgenic algae with genetic stability. Copper (Cu) was used for heavy metal treatment. We performed the heavy metal treatment with a certain concentration to transgenic lines and developed a series of determation and analysis of physiological and biochemical indexes. According to our results,35S:.CrGNAT transgenic lines showed a higher tolerance than wide-type algae under Cu treatment, which specifically exhibited as higher cell growth number and cellular chlorophyll content. In contrast, the 35S::Anti-CrGNAT anti-expressing algae were more sensitive to Cu toxicity than wild-type, because they were easier to die under the heavy metal treatment. Furthermore, expression levels of the gene were positively proportional to the toxic degree of cells under Cu treatments. All these results indicated that the gene CrGNAT could regulate the tolerance of Chlamydomonas reinhardtii to heavy metal stress.