The unexplored direct response of leaf stomata to temperature (DRST): patterns, mechanisms and impacts

植物通过从空气中吸收二氧化碳，并利用太阳的能量将其转化为糖，提供陆地上生命使用的所有能源。在这个过程中，水分从树叶中蒸发。事实上，大部分以雨水形式落下的水在从树叶蒸发后返回大气。了解植物如何调节水分损失是至关重要的，这既是为了确定哪些基因控制了这种调节，以便育种者能够提高作物水分的利用效率，也是为了能够准确预测波动的天气和气候将如何影响作物、牧场和森林的水分损失。植物通过打开和关闭叶子表面的毛孔来调节水分的流失--例如，它们在阳光下打开，在土壤干燥时关闭。然而，人们对温度变化如何影响这些毛孔知之甚少。这项研究将确定60种物种的这些影响，这些物种被选为代表地球上最主要的栖息地；测试已发现的任何温度反应的生物学原因的假设；并将这些发现纳入计算机模型，以预测温度反应如何影响植物生长和水分损失。除了对本科生和研究生进行现代实验植物生物学的培训外，还将开发一个体验式项目，来自附近一所有大量贫困学生的高中的学生将建造跨越不同温度范围的户外生长室。这些实验室将允许学生第一手观察即使是微小的温度差异如何对植物生长和产量产生巨大影响。关于气孔对温度的反应知之甚少，尽管已有文献表明温度通过叶片与空气的水汽压差(VPDLeaf)间接影响气孔。当叶片变暖时，由于叶片空气中饱和水蒸气压的上升，VPD叶迅速增加，导致气孔关闭。但气孔对温度的直接反应(DRST)--当VPD叶保持不变时对温度的反应--对于完整的叶片来说很少有报道，其潜在的机制和生态多样性在很大程度上是未知的。缺乏对DRST的了解可能会扭曲碳和水通量的模型，阻碍对全球变暖中植物功能的准确预测和理解。这项研究将量化横跨世界主要功能类型和生态系统的物种以及来自不同的世界性分支(葡萄属)的10个物种和品种的DRST及其对生长温度的适应；测试预测的DRST的适应性、生物地理学和进化趋势；测试DRST的主要假设机制，并利用结果改进气孔导度的机理模型；并将所获得的知识应用于功能-结构3D树冠模型，以量化DRST如何在一系列时间尺度上影响综合碳和水通量。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Plants provide all the energy used by life on land, by taking CO2 from the air and using energy from the sun to turn it into sugar. During this process, water evaporates from leaves. In fact, most of the water that falls as rain returns to the atmosphere after evaporating from leaves. It is essential to understand how plants regulate water loss, both to identify which genes control that regulation, so that breeders can improve crop water use efficiency, and also to enable accurate predictions of how fluctuating weather and climate will affect water loss from crops, rangelands, and forests. Plants regulate water loss by opening and closing pores on the surfaces of leaves – for example, they open in sunlight, and close when soil is dry. However, little is known about how changes in temperature affect these pores. This study will determine those effects for 60 species, selected to represent most major habitats on Earth; test hypotheses for the biological causes of any temperature responses that are discovered; and incorporate these discoveries in a computer model to predict how temperature responses affect plant growth and water loss. In addition to training of undergraduate and graduate students in modern experimental plant biology, an experiential project will be developed in which students from a nearby high school with a large population of underprivileged students, will build outdoor growth chambers spanning a range of different temperatures. These chambers will allow students to observe firsthand how even small differences in temperature can have dramatic effects on plant growth and yield. Little is known about stomatal responses to temperature, although it is well-documented that temperature affects stomata indirectly via the leaf-to-air vapor pressure difference (VPDleaf). VPDleaf increases rapidly as leaves warm due to rising saturation vapor pressure in the leaf airspaces, causing stomata to close. But the direct response of stomata to temperature (DRST) – the response to temperature when VPDleaf is held constant – has rarely been reported for intact leaves, leaving the underlying mechanisms and ecological diversity largely unknown. Lack of knowledge of the DRST may skew models of carbon and water flux, preventing accurate prediction and understanding of plant function in a warming world. This study will quantify the DRST and its acclimation to growth temperature in species spanning the world's major functional types and ecosystems, plus 10 species and cultivars from a diverse, cosmopolitan clade (the genus Vitis); test predicted adaptive, biogeographic, and evolutionary trends in the DRST; test major hypothetical mechanisms for the DRST and use the results to refine a mechanistic model of stomatal conductance; and apply the resulting knowledge to a functional-structural 3D canopy model to quantify how the DRST affects integrated carbon and water fluxes at a range of time scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.