Independent colimitation for carbon dioxide and inorganic phosphorus.
Independent colimitation for carbon dioxide and inorganic phosphorus.
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DOI：
10.1371/journal.pone.0028219
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Gaedke U
中科院分区：
文献类型：
--
作者：
Spijkerman E;de Castro F;Gaedke U
两种或两种以上营养物质同时限制植物生长是自然界中的一种普遍现象，但其细胞机制尚不清楚。研究了在二氧化碳和磷的限制条件下，嗜酸衣藻对二氧化碳和磷的吸收动力学。此外，我们将数据与四个不同的Monod型模型进行了拟合：一个假设利比斯最小定律，一个假设对一种养分的吸收亲和力不受另一种养分的供应的影响(独立比较)，以及两种模型，其中一种养分的吸收亲和力取决于另一种养分的供应(依赖比较)。此外，我们还询问了共培养条件下的生理反应是否与单一营养限制下的生理反应不同。我们发现摄取这两种营养素的亲和力之间没有负相关，因此拒绝了依赖的比较。动力学数据得到了更好的模型拟合，假设独立吸收共生营养物质，而不是假设利比斯最小定律或依赖共生共生。结果表明，细胞营养动态平衡调节了营养物质的获取，导致了二氧化碳和磷的最大吸收速率的权衡，这可能是由于细胞膜上不同营养物质的转运蛋白的空间限制所致。因此，对混配的反应偏离了对单一营养限制的反应。总而言之，对单一营养限制的反应不能外推到多种营养限制的情况，这需要比较实验和模型来正确预测对不断变化的自然环境的生长反应。在共生和独立共生条件下，这些偏离单一营养限制反应的情况也可能适用于藻类和高等植物中的其他营养物质。
Simultaneous limitation of plant growth by two or more nutrients is increasingly acknowledged as a common phenomenon in nature, but its cellular mechanisms are far from understood. We investigated the uptake kinetics of CO2 and phosphorus of the algae Chlamydomonas acidophila in response to growth at limiting conditions of CO2 and phosphorus. In addition, we fitted the data to four different Monod-type models: one assuming Liebigs Law of the minimum, one assuming that the affinity for the uptake of one nutrient is not influenced by the supply of the other (independent colimitation) and two where the uptake affinity for one nutrient depends on the supply of the other (dependent colimitation). In addition we asked whether the physiological response under colimitation differs from that under single nutrient limitation. We found no negative correlation between the affinities for uptake of the two nutrients, thereby rejecting a dependent colimitation. Kinetic data were supported by a better model fit assuming independent uptake of colimiting nutrients than when assuming Liebigs Law of the minimum or a dependent colimitation. Results show that cell nutrient homeostasis regulated nutrient acquisition which resulted in a trade-off in the maximum uptake rates of CO2 and phosphorus, possibly driven by space limitation on the cell membrane for porters for the different nutrients. Hence, the response to colimitation deviated from that to a single nutrient limitation. In conclusion, responses to single nutrient limitation cannot be extrapolated to situations where multiple nutrients are limiting, which calls for colimitation experiments and models to properly predict growth responses to a changing natural environment. These deviations from single nutrient limitation response under colimiting conditions and independent colimitation may also hold for other nutrients in algae and in higher plants.