Plastic and adaptive responses of plant respiration to changes in atmospheric CO2 concentration
Plastic and adaptive responses of plant respiration to changes in atmospheric CO2 concentration
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DOI：
10.1111/j.1399-3054.2009.01262.x
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发表时间：
2009-12-01
影响因子：
6.4
通讯作者：
Gomez-Casanovas, Nuria
中科院分区：
文献类型：
--
作者：
Gonzalez-Meler, Miquel A.;Blanc-Betes, Elena;Gomez-Casanovas, Nuria
大气中CO2的浓度已从低于200亩升-1在末次冰期最大的更新世晚期到近280亩升-1在全新世开始，并不断增加，因为工业革命的开始。植物对大气CO2水平增加的大多数反应导致光合作用、水分利用效率和生物量增加。鲜为人知的是，呼吸作用可能在植物对大气CO2变化的适应性反应中发挥作用。尽管植物呼吸作用不会随着CO2增强的光合作用或生长速率成比例地增加，但在低于环境CO2的条件下生长的植物中呼吸作用成本的降低有助于维持植物正碳平衡（即提高光合作用与呼吸作用的比率）。对植物呼吸作用的理解由于替代途径的存在而进一步复杂化，该替代途径消耗光合产物而不产生化学能[三磷酸腺苷（ATP）]，其有效性与通过正常细胞色素途径的呼吸作用相同。在这里，我们提出的拟南芥植物选择在更新世（200亩升-1），目前全新世（370亩升-1），和升高（700亩升-1）浓度的CO（2）和生长在当前的CO2水平的呼吸反应。我们发现，呼吸速率较低更新世适应的植物相比，全新世的，呼吸的大幅减少是因为减少活动的替代途径。在文献的调查中，我们发现，在不同的植物生长形式和CO2水平的呼吸作用的变化可以部分地解释为维持生物量的呼吸能量需求的差异。这一趋势在拟南芥实验中得到证实，其中更新世适应的植物表现出呼吸作用的减少，而组织中的N含量没有同时减少。有趣的是，适应CO2浓度升高的植物的氮基呼吸速率也降低了。因此，ATP产量每单位的N增加更新世适应的植物相比，目前的CO2适应。我们的研究结果表明，线粒体能量耦合和替代途径介导的呼吸作用对大气CO2变化的反应可能会提高植物在低CO2水平下的生存能力，以帮助克服低碳平衡。因此，在所有情况下，旁路途径的基础活性的增加不一定与植物代谢胁迫相关。
The concentration of atmospheric CO2 has increased from below 200 mu l l-1 during last glacial maximum in the late Pleistocene to near 280 mu l l-1 at the beginning of the Holocene and has continuously increased since the onset of the industrial revolution. Most responses of plants to increasing atmospheric CO2 levels result in increases in photosynthesis, water use efficiency and biomass. Less known is the role that respiration may play during adaptive responses of plants to changes in atmospheric CO2. Although plant respiration does not increase proportionally with CO2-enhanced photosynthesis or growth rates, a reduction in respiratory costs in plants grown at subambient CO2 can aid in maintaining a positive plant C-balance (i.e. enhancing the photosynthesis-to-respiration ratio). The understanding of plant respiration is further complicated by the presence of the alternative pathway that consumes photosynthate without producing chemical energy [adenosine triphosphate (ATP)] as effectively as respiration through the normal cytochrome pathway. Here, we present the respiratory responses of Arabidopsis thaliana plants selected at Pleistocene (200 mu l l-1), current Holocene (370 mu l l-1), and elevated (700 mu l l-1) concentrations of CO(2)and grown at current CO2 levels. We found that respiration rates were lower in Pleistocene-adapted plants when compared with Holocene ones, and that a substantial reduction in respiration was because of reduced activity of the alternative pathway. In a survey of the literature, we found that changes in respiration across plant growth forms and CO2 levels can be explained in part by differences in the respiratory energy demand for maintenance of biomass. This trend was substantiated in the Arabidopsis experiment in which Pleistocene-adapted plants exhibited decreases in respiration without concurrent reductions in tissue N content. Interestingly, N-based respiration rates of plants adapted to elevated CO2 also decreased. As a result, ATP yields per unit of N increased in Pleistocene-adapted plants compared with current CO2 adapted ones. Our results suggest that mitochondrial energy coupling and alternative pathway-mediated responses of respiration to changes in atmospheric CO2 may enhance survival of plants at low CO2 levels to help overcome a low carbon balance. Therefore, increases in the basal activity of the alternative pathway are not necessarily associated to metabolic plant stress in all cases.