Gesch RW, Boote KJ, Vu JC, Bowes G
Department of Agronomy (R.W.G., K.J.B.).
Plant Physiol. 1998 Oct;118(2):521-9. doi: 10.1104/pp.118.2.521.
The accumulation of soluble carbohydrates resulting from growth under elevated CO2 may potentially signal the repression of gene activity for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcS). To test this hypothesis we grew rice (Oryza sativa L.) under ambient (350 &mgr;L L-1) and high (700 &mgr;L L-1) CO2 in outdoor, sunlit, environment-controlled chambers and performed a cross-switching of growth CO2 concentration at the late-vegetative phase. Within 24 h, plants switched to high CO2 showed a 15% and 23% decrease in rbcS mRNA, whereas plants switched to ambient CO2 increased 27% and 11% in expanding and mature leaves, respectively. Ribulose-1,5-bisphosphate carboxylase/oxygenase total activity and protein content 8 d after the switch increased up to 27% and 20%, respectively, in plants switched to ambient CO2, but changed very little in plants switched to high CO2. Plants maintained at high CO2 showed greater carbohydrate pool sizes and lower rbcS transcript levels than plants kept at ambient CO2. However, after switching growth CO2 concentration, there was not a simple correlation between carbohydrate and rbcS transcript levels. We conclude that although carbohydrates may be important in the regulation of rbcS expression, changes in total pool size alone could not predict the rapid changes in expression that we observed.
在二氧化碳浓度升高条件下生长所导致的可溶性碳水化合物积累，可能会潜在地引发对1,5-二磷酸核酮糖羧化酶/加氧酶（rbcS）小亚基基因活性的抑制。为验证这一假设，我们在室外阳光充足且环境可控的生长箱中，让水稻（Oryza sativa L.）分别在环境二氧化碳浓度（350 μL L-1）和高二氧化碳浓度（700 μL L-1）下生长，并在营养生长后期对生长二氧化碳浓度进行交叉切换。在切换后的24小时内，转至高二氧化碳环境的植株rbcS mRNA分别下降了15%和23%，而转至环境二氧化碳环境的植株，其正在伸展的叶片和成熟叶片中的rbcS mRNA分别增加了27%和11%。切换8天后，转至环境二氧化碳环境的植株中，1,5-二磷酸核酮糖羧化酶/加氧酶的总活性和蛋白质含量分别增加了高达27%和20%，而转至高二氧化碳环境的植株变化很小。与处于环境二氧化碳浓度下的植株相比，维持在高二氧化碳浓度下的植株具有更大的碳水化合物库规模和更低的rbcS转录水平。然而，在切换生长二氧化碳浓度后，碳水化合物与rbcS转录水平之间并没有简单的相关性。我们得出结论，虽然碳水化合物在rbcS表达调控中可能很重要，但仅碳水化合物库规模的变化并不能预测我们所观察到的rbcS表达的快速变化。
