Abstract
Recently, we have reported that a shift of the optimum temperature for photosynthesis in spinach (Spinacia oleracea) is largely attributed to changes in the temperature dependence of Rubisco carboxylation. In this study, to clarify biochemical and molecular mechanisms of the shift of the optimum temperature for photosynthesis, we grew spinach at 15C or 30C and examined Rubisco characteristics.
Purified Rubisco from leaves grown at 15C was less thermally stable than that at 30C. Using the two-dimensional gel electrophoresis, we revealed that the isoelectric points in Rubisco small subunits were different between the growth temperatures. These results would indicate that, in spinach grown at the lower temperature, Rubisco isozyme(s) having greater activity at the lower temperature are expressed, or some post-translational modifications of Rubisco small subunits occur differently depending on the growth temperatures. These changes of Rubisco characteristics may contribute to the shift of the optimum temperature for photosynthesis.
