Determination of Photosynthesis-Related and Ascorbate Peroxidase Gene Expression in the Green Algae (Chlorella vulgaris) Under High-Temperature Conditions

Increasing water temperatures because of climate change resulted in population shifts and physiological responses in aquatic environments. In this study, short-term high-temperature condition effects on green algae Chlorella vulgaris were investigated at transcriptional and physiological levels. The photosystem II D1 protein ( psbA ) gene, a large unit of Rubisco ( rbcL ) gene and chloroplastic ascorbate peroxidase ( cAPX ) gene expressions were quantified using semi-quantitative real time-PCR. The psbA gene transcription level at 45˚C for 48 and 72 h was reduced by approx. 2.22 and 2.86-folds, respectively. The rbcL gene transcription level was also reduced by 1.54 relative to the control at 72 h. Our APX gene transcriptional level results indicated that the transcription of this gene was significantly increased at 35˚C at 24, 48, and 72 h. In contrast, the cAPX mRNA transcript level was reduced by approx. 2 times compared with the control. Our data demonstrated that alteration cAPX gene expression could play an essential role in high-temperature acclimation in C. vulgaris .