Physiological responses to water stress and stress memory in Argania spinosa

Abstract

Drought stress is one of the major abiotic stress factors shifting the physiology and metabolism of the plants. In semiarid areas, drought stress events are often recurrent, and plants have developed strategies to remember a first so-called priming stress to eventually respond more effectively to a second triggering stress. In this study, we tested several physiological and morphological variables in Argania spinosa (L.) Skeels plants, growing in greenhouse conditions under a drought treatment induced by water withholding. Two sequential one-month periods of water stress were imposed to understand the stress memory events in this species The plants were divided into two groups depending on the treatment applied (irrigated and stressed) which later, after one month of a recuperation phase, were divided again into two more groups (having a total of four at the end of the study). Leaf samples were periodically taken and relative water content, gas exchange, chlorophyll content and other variables were measured, analysed and compared between those groups. Plants, which have suffered the two sequential water stress periods, were more affected according to several variables than plants subjected to only one stress treatment, so we finally conclude that this species does not seem to have any drought stress memory mechanisms for the studied variables, under the conditions of this experiment.