A Dynamic Hydro-Mechanical and Biochemical Model of Stomatal Conductance for C4 Photosynthesis
A Dynamic Hydro-Mechanical and Biochemical Model of Stomatal Conductance for C4 Photosynthesis
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DOI：
10.1104/pp.17.00666
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发表时间：
2017-09-01
期刊：
影响因子：
7.4
通讯作者：
Beerling, David J.
中科院分区：
文献类型：
--
作者：
Bellasio, Chandra;Quirk, Joe;Beerling, David J.
C-4植物是主要的谷物（玉米[Zea mays]和高粱[Sorghum bicolor]）、糖（甘蔗[Escherichum officinarum]）和生物燃料（芒草属）。生产者并做出贡献;为全球生产力贡献20%。植物通过气孔损失水分以获得CO2（同化[A]）并通过调节气孔导度（gS）来控制其碳-水平衡。机械地预测GS和A响应于大气CO2、水的可用性和时间的能力对于模拟当前、过去或未来环境条件下植物-大气碳和水交换的气孔控制是至关重要的。然而，gS的动态机制模型缺乏，特别是C4光合作用。我们开发和耦合的气孔行为的流体力学模型与C-4光合作用的生化模型，校准在玉米中使用气体交换测量，并扩展耦合模型与时间显式函数来预测动态响应。我们证明了更广泛的适用性的模型与三个额外的C-4草种，其中种间差异的气孔行为可以解释为通过拟合一个单一的参数。该模型准确地预测了稳态响应gS光，大气CO2和氧气，土壤干燥，蒸发需求以及动态响应光强度。进一步的分析表明，叶片导水率的变化的影响是可以忽略的。在此基础上，我们推导出一套适合于陆面模式的方程。我们的模型阐明了C-4植物气孔控制的基础过程，并表明与C-4草的快速气孔响应相关的水力效益可能支持了C-4光合作用的进化。
C-4 plants are major grain (maize [Zea mays] and sorghum [Sorghum bicolor]), sugar (sugarcane [Saccharum officinarum]), and biofuel (Miscanthus spp.) producers and contribute; 20% to global productivity. Plants lose water through stomatal pores in order to acquire CO2 (assimilation [A]) and control their carbon-for-water balance by regulating stomatal conductance (gS). The ability to mechanistically predict gS and A in response to atmospheric CO2, water availability, and time is critical for simulating stomatal control of plant-atmospheric carbon and water exchange under current, past, or future environmental conditions. Yet, dynamic mechanistic models for gS are lacking, especially for C-4 photosynthesis. We developed and coupled a hydromechanical model of stomatal behavior with a biochemical model of C-4 photosynthesis, calibrated using gas-exchange measurements in maize, and extended the coupled model with time-explicit functions to predict dynamic responses. We demonstrated the wider applicability of the model with three additional C-4 grass species in which interspecific differences in stomatal behavior could be accounted for by fitting a single parameter. The model accurately predicted steady-state responses of gS to light, atmospheric CO2 and oxygen, soil drying, and evaporative demand as well as dynamic responses to light intensity. Further analyses suggest that the effect of variable leaf hydraulic conductance is negligible. Based on the model, we derived a set of equations suitable for incorporation in land surface models. Our model illuminates the processes underpinning stomatal control in C-4 plants and suggests that the hydraulic benefits associated with fast stomatal responses of C-4 grasses may have supported the evolution of C-4 photosynthesis.