Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan CREST, JST, Tokyo, Japan.
Physiol Plant. 2012 Dec;146(4):404-12. doi: 10.1111/j.1399-3054.2012.01631.x. Epub 2012 May 10.
The limiting step of photosynthesis changes depending on CO(2) concentration and, in theory, photosynthetic nitrogen use efficiency at a respective CO(2) concentration is maximized if nitrogen is redistributed from non-limiting to limiting processes. It has been shown that some plants increase the capacity of ribulose-1,5-bisphoshate (RuBP) regeneration (evaluated as J(max) ) relative to the RuBP carboxylation capacity (evaluated as V(cmax) ) at elevated CO(2) , which is in accord with the theory. However, there is no study that tests whether this change is accompanied by redistribution of nitrogen in the photosynthetic apparatus. We raised a perennial plant, Polygonum sachalinense, at two nutrient availabilities under two CO(2) concentrations. The J(max) to V(cmax) ratio significantly changed with CO(2) increment but the nitrogen allocation among the photosynthetic apparatus did not respond to growth CO(2) . Enzymes involved in RuBP regeneration might be more activated at elevated CO(2) , leading to the higher J(max) to V(cmax) ratio. Our result suggests that nitrogen partitioning is not responsive to elevated CO(2) even in species that alters the balance between RuBP regeneration and carboxylation. Nitrogen partitioning seems to be conservative against changes in growth CO(2) concentration.
光合作用的限速步骤取决于 CO2 浓度，并且在理论上，如果氮从非限制过程重新分配到限制过程，那么在相应的 CO2 浓度下，光合作用的氮利用效率将达到最大化。已经表明，一些植物在高 CO2 下增加了核酮糖-1,5-二磷酸（RuBP）再生的能力（评估为 J(max)）相对于 RuBP 羧化能力（评估为 V(cmax)），这与理论相符。然而，尚无研究测试这种变化是否伴随着光合器官中氮的重新分配。我们在两种 CO2 浓度下的两种养分供应条件下培养了一种多年生植物，Polygonum sachalinense。J(max) 与 V(cmax) 的比值随 CO2 增加而显著变化，但光合器官中的氮分配对生长 CO2 没有反应。在高 CO2 下，可能会更激活参与 RuBP 再生的酶，从而导致更高的 J(max) 与 V(cmax) 比值。我们的结果表明，即使在改变 RuBP 再生和羧化之间平衡的物种中，氮的分配也不会对升高的 CO2 做出响应。氮的分配似乎对生长 CO2 浓度的变化具有保守性。
