Laboratory of Crop Physiology (LCroP), Department of Plant Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, Brazil.
Laboratory of Plant Physiology 'Coaracy M. Franco', Center for Research and Development in Ecophysiology and Biophysics, Agronomic Institute (IAC), Campinas, SP, Brazil.
J Plant Physiol. 2021 May;260:153397. doi: 10.1016/j.jplph.2021.153397. Epub 2021 Mar 3.
Stability is a key trait for plant growth and development in a changing environment, involving homeostasis and resilience. While homeostasis refers to the maintenance of the internal structural and functional plant integrity, resilience is associated with the plant ability in returning to the initial conditions after a given disturbance. Such concepts are especially relevant for perennial and semi-perennial plants facing seasonal and frequent stress conditions. Although plant memory is closely associated with plant performance under recurrent stresses, to date, there is no study evaluating how stress memory is linked to stability under varying water conditions. Herein, we evaluated the association between drought stability and memory in sugarcane plants and proposed a new stability index to evaluate plant memory. Two datasets were analyzed, the first deals with leaf gas exchange and photochemistry of sugarcane plants grown in nutrient solution and exposed to one, two or three water deficit cycles. The second takes into account the physiological performance of sugarcane propagules obtained by vegetative propagation from plants that faced drought. To quantify sugarcane stability, we estimated the drought impact, the disturbance rate (DR), drought perturbation, and recovery rate (RR) for plants from both datasets. Drought memory - given by improved performance after previous stress events or when origin material faced drought - was detected in both datasets, changing either DR or RR. Based on these indices, we proposed the overall stability (OSt), defined as the ratio between RR and DR. While DR is associated to plant homeostasis, RR is a measure of plant resilience. Sugarcane plants exposed to three cycles of water deficit or those propagules originated from stressed plants presented the highest OSt values, showing higher RR and/or lower DR when compared to well-watered plants or to propagules from well-watered plants. Regarding the physiological traits evaluated, leaf CO assimilation and stomatal conductance were the most consistent variables in revealing drought stability and memory. Concluding, OSt revealed consistently patterns of response associated with plant memory, besides quantifying plant stability under stressful conditions.
稳定性是植物在变化环境中生长和发育的关键特性，涉及到内稳态和弹性。内稳态是指维持植物内部结构和功能的完整性，而弹性则与植物在受到给定干扰后恢复初始状态的能力有关。这些概念对于面临季节性和频繁胁迫条件的多年生和半多年生植物尤其重要。尽管植物记忆与植物在反复胁迫下的表现密切相关，但迄今为止，还没有研究评估胁迫记忆与不同水分条件下的稳定性之间的关系。在此，我们评估了甘蔗植物干旱稳定性和记忆之间的关联，并提出了一个新的稳定性指数来评估植物记忆。分析了两个数据集，第一个数据集涉及在营养液中生长并暴露于一个、两个或三个水分亏缺循环的甘蔗植物的叶片气体交换和光化学；第二个数据集考虑了通过无性繁殖从经历干旱的植物获得的甘蔗繁殖体的生理性能。为了量化甘蔗的稳定性，我们估计了干旱的影响、数据集 1 中植物的干扰率 (DR)、干旱扰动和恢复率 (RR)，以及数据集 2 中植物的 DR 和 RR。在两个数据集都检测到了干旱记忆 - 即通过以前的胁迫事件或当原始材料面临干旱时提高性能 - 改变了 DR 或 RR。基于这些指数，我们提出了整体稳定性 (OSt)，定义为 RR 与 DR 的比值。虽然 DR 与植物内稳态有关，但 RR 是植物弹性的衡量标准。暴露于三个水分亏缺循环或来自胁迫植物的繁殖体的甘蔗植物表现出最高的 OSt 值，与充分浇水的植物或来自充分浇水的植物的繁殖体相比，RR 更高且/或 DR 更低。关于评估的生理特征，叶片 CO2 同化和气孔导度是揭示干旱稳定性和记忆的最一致变量。综上所述，OSt 一致地揭示了与植物记忆相关的反应模式，同时量化了植物在胁迫条件下的稳定性。
