The plant canopy functions as an aerial array of light-harvesting antennas. To achieve maximal yield, each leaf within this array and the array as a whole need to rapidly adjust to naturally occurring fluctuations in light intensity and quality. Excessive light stress triggers the closing of pores in leaves called stomata to minimize moisture loss. We found that different leaves within the canopy of an Arabidopsis thaliana plant, including leaves not directly exposed to light, coordinated stomatal closure in response to light stress by sending and receiving rapid systemic signals. This response required the plant hormones abscisic acid and jasmonic acid and was mediated by a rapid autopropagating wave of reactive oxygen species (ROS) production. Furthermore, this response depended on the function of genes encoding the ROS-generating NADPH oxidase RBOHD and various stomatal regulators, such as the anion channel SLAC1, GHR1 (guard cell hydrogen peroxide resistant 1), and lipoxygenase 1 (LOX1). Our findings reveal that plants function as highly dynamic and coordinated organisms, optimizing the overall response of their canopies to fluctuating light intensities.

植物冠层用作光收集天线的天线阵列。为了获得最大产量，该阵列内的每个叶片以及整个阵列都需要快速调整以适应自然发生的光强度和质量波动。过度的光线胁迫会导致被称为气孔的叶片气孔关闭，从而最大程度地减少水分流失。我们发现拟南芥冠层内的不同叶片通过发送和接收快速的系统信号，植物（包括未直接暴露于阳光下的叶子）协调气孔关闭，以响应光胁迫。这种反应需要植物激素脱落酸和茉莉酸，并通过活性氧（ROS）产生的快速自动繁殖波来介导。此外，这种反应取决于编码产生ROS的NADPH氧化酶RBOHD的基因和各种气孔调节剂的功能，例如阴离子通道SLAC1，GHR1（抗氧化过氧化氢的保卫细胞1）和脂氧合酶1（LOX1）。我们的发现表明，植物是高度动态和协调的有机体，可优化其冠层对波动的光照强度的整体响应。