Data from: High-resolution thermal imagery reveals how interactions between crown structure and genetics shape plant temperature

Understanding interactions between environmental stress and genetic variation is crucial to predict the adaptive capacity of species to climate change. Leaf temperature is both a driver and a responsive indicator of plant physiological response to thermal stress, and methods to monitor it are needed. Foliar temperatures vary across leaf to canopy scales and are influenced by genetic factors, challenging efforts to map and model this critical variable. Thermal imagery collected using unoccupied aerial systems (UAS) offers an innovative way to measure thermal variation in plants across landscapes at leaf-level resolutions. We used a UAS equipped with a thermal camera to assess temperature variation among genetically distinct populations of big sagebrush (Artemisia tridentata), a keystone plant species that is the focus of intensive restoration efforts throughout much of western North America. We completed flights across a growing season in a sagebrush common garden to map leaf temperature relative to subspecies and cytotype, physiological phenotypes of plants, and summer heat stress. Our objectives were to: (1) determine whether leaf-level stomatal conductance corresponds with changes in crown temperature; (2) quantify genetic (i.e., subspecies and cytotype) contributions to variation in leaf and crown temperatures; and (3) identify how crown structure, solar radiation, and subspecies-cytotype relate to leaf-level temperature. Stomatal conductance was negatively, non-linearly correlated with crown-level temperature derived from UAS. Subspecies identity best explained crown-level temperature with no difference observed between cytotypes. However, structural phenotypes and microclimate best explained leaf-level temperature. These results show how fine-scale thermal mapping can decouple the contribution of genetic, phenotypic, and environmental factors on leaf temperature dynamics. As climate-change-induced heat stress becomes prevalent, thermal UAS represents a promising way to track plant phenotypes that emerge from gene-by-environment interactions.

探究环境胁迫与遗传变异之间的相互作用对于预测物种适应气候变化的能力至关重要。叶片温度既是植物对热胁迫生理反应的驱动因素，也是其响应的指示器，因此需要监测其变化的方法。叶片温度在叶片到冠层尺度上存在差异，并受遗传因素的影响，这对绘制和模拟这一关键变量构成了挑战。利用无人空中系统（UAS）收集的热成像提供了一种创新的方法来测量植物在景观尺度上的叶片层面的温度变化。我们使用配备热相机的UAS评估了大 Sagebrush（Artemisia tridentata）不同遗传种群间的温度变化，大 Sagebrush是一种关键植物物种，是北美西部大部分地区修复工作重点关注的对象。我们在灌木常见园中完成了一季的生长季节飞行，以绘制叶片温度相对于亚种和细胞型的关系，植物的生理表型，以及夏季热胁迫。我们的目标是：(1)确定叶片层面的气孔导度是否与树冠温度的变化相对应；(2)量化遗传因素（即亚种和细胞型）对叶片和树冠温度变化的贡献；(3)识别树冠结构、太阳辐射以及亚种-细胞型与叶片层面温度之间的关系。气孔导度与UAS获取的树冠层温度呈负相关，且与细胞型之间没有观察到差异。然而，结构表型和微气候最能解释叶片层面的温度。这些结果展示了精细尺度热制图如何解耦遗传、表型和环境因素对叶片温度动态的贡献。随着由气候变化引起的热胁迫变得越来越普遍，热UAS成为追踪基因与环境相互作用产生的植物表型的一种有前景的方法。