Effects of low temperature stress on photosynthesis in sikRbcs2 transgenic tobacco

1,5-Diphosphate ribulose carboxylase/oxygenase (EC 4.1.1.39, Rubisco) is the key enzyme in the metabolism of photosynthetic carbon in higher plants, and it catalyzes CO2 fixation and reduction. Rubisco controls the metabolic rate of photosynthesis and photorespiration and has a critical effect on the net photosynthetic rate. The enzyme comprises eight major subunit (rbcL) and eight small subunit (rbcs) L8S8 polymer composites. The expression of small subunits is important for regulating the expression of large subunits. Enzyme activity is important in photosynthetic electron transport and photochemical quenching. To study the effects of the S. involucrata sikRbcs2 gene on plant photosynthesis under cold conditions, sikRbcs2-transgenic tobacco and non-transgenic tobacco plants were exposed to various temperatures (16, 10, 6,and 4) under low light (70 mu mol m-2 s-1) for 72 h, and the chloroplast pigment content, photosynthetic rate, and chlorophyll fluorescence parameters were measured in the leaves. The results indicate that low temperatures damage non-transgenic tobacco.