The effect of temperature on the photosynthetic rate of wild-type and mutant Chlamydomonas reinhardtii

Abstract

The effect of temperature on the photosynthetic rate of Chlamydomonas reinhardtii wild type (CC-1690 - wild type mt+ 21 gr) and mutant (CC-3913 - pf9-3-mt-) was studied in this experiment by the measurement of oxygen production under treatments of 15°C, 22°C, and 27°C. We predicted that the mutant would produce less oxygen than the wild type due to the lack of flagella, and that decreasing temperature would decrease the photosynthetic rate due a decrease in kinetic energy (Lambers et al. 2008, Petrucci et al. 2011). Our results showed that the wild type produced significantly more oxygen than the mutant for the 15°C and 27°C treatments (0.27mg/L and 1.24 mg/L more oxygen, respectively), allowing us to reject Ho₁ for these treatments.We also found that decreasing temperature decreases oxygen production of the wild type with significant differences in the oxygen production between the 15°C (0.27±0.1mg/L) and 22°C (1.2±0.2mg/L) treatments, as well as between the 15°C (0.27±0.1mg/L) and 27°C (1.6±0.4mg/L) treatments.  This trend, however, is not consistent with the results of the mutant; therefore, we were failed to reject Ho₂. The mutant’s oxygen production peaked at 22°C with a production of 0.84±0.1mg/L, and then dropped at 27°C to a production of 0.36±0.1mg/L.These results suggest that mutant strain CC-3913 - pf9-3-mt- may be a temperature-sensitive mutant, and likely has reduced RuBisCO carboxylase activity at certain temperatures (Spreitzer et al. 1988).