Phosphorus recycling in photorespiration maintains high photosynthetic capacity in woody species
Phosphorus recycling in photorespiration maintains high photosynthetic capacity in woody species
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DOI：
10.1111/pce.12468
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发表时间：
2015-06-01
影响因子：
7.3
通讯作者：
Cooke, Julia
中科院分区：
文献类型：
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作者：
Ellsworth, David S.;Crous, Kristine Y.;Cooke, Julia
叶片光合作用对CO2的响应可以深入了解主要营养物质，如磷(P)如何限制叶片CO2同化速率（A（净））。然而，在经典的光合作用模型中很少采用三磷酸限制，并且不确定这些限制在多大程度上发生在田间情况下。与光合作用生化理论的预测相反，我们发现高[CO2]和低[O-2]条件下的A（净）比环境[O-2]条件下的低。10种乔灌木在不同土壤磷有效性范围内，均未表现出饱和[CO2]（即a (max)）至2kPa O-2时a（净）的正响应。在低[O-2]条件下，3个物种的A（max）降低了约20%，这一现象可能是光呼吸过程中正磷酸盐（P-i）的节约。与生长在缺磷土壤中的物种相比，这些物种光合能力最大，P-i含量为2mmol Pm-2，对光呼吸所提供的额外P-i依赖最大。结果表明，很少使用生化光合作用模型的调整有助于预测a (max)，并深入了解叶片P浓度范围内光合作用速率的生化限制。磷酸盐对光合能力的限制在田间可能比以前认为的更常见。
Leaf photosynthetic CO2 responses can provide insight into how major nutrients, such as phosphorus (P), constrain leaf CO2 assimilation rates (A(net)). However, triose-phosphate limitations are rarely employed in the classic photosynthesis model and it is uncertain as to what extent these limitations occur in field situations. In contrast to predictions from biochemical theory of photosynthesis, we found consistent evidence in the field of lower A(net) in high [CO2] and low [O-2] than at ambient [O-2]. For 10 species of trees and shrubs across a range of soil P availability in Australia, none of them showed a positive response of A(net) at saturating [CO2] (i.e. A(max)) to 2kPa O-2. Three species showed >20% reductions in A(max) in low [O-2], a phenomenon potentially explained by orthophosphate (P-i) savings during photorespiration. These species, with largest photosynthetic capacity and P-i>2mmol Pm-2, rely the most on additional P-i made available from photorespiration rather than species growing in P-impoverished soils. The results suggest that rarely used adjustments to a biochemical photosynthesis model are useful for predicting A(max) and give insight into the biochemical limitations of photosynthesis rates at a range of leaf P concentrations. Phosphate limitations to photosynthetic capacity are likely more common in the field than previously considered.