Abstract
Although plant responses to drought stress have been studied in detail in several plant species, including CAM plants, the occurrence of stress memory and possible mechanisms for its regulation are still very poorly understood. In an attempt to better understand the occurrence and possible mechanisms of regulation of stress memory in plants, we measured the concentrations of phytohormones in Aptenia cordifolia exposed to reiterated drought, together with various stress indicators, including leaf water contents, photosynthesis and mechanisms of photo- and antioxidant protection. Results showed that plants exposed to drought stress responded differently if previously challenged with a first drought. Gibberellin levels decreased upon exposure to the first drought and remained lower in double-stressed plants compared with those exposed to stress for the first time. In contrast, abscisic acid levels were higher in double- than single-stressed plants. This occurred in parallel with alterations in hydroperoxide levels, but not with malondialdehyde levels, thus suggesting an increased oxidation state that did not result in oxidative damage in double-stressed plants. It is concluded that (i) drought stress memory occurs in double-stressed A. cordifolia plants, (ii) both gibberellins and abscisic acid may play a role in plant response to repeated periods of drought, and (iii) changes in abscisic acid levels in double-stressed plants may have a positive effect by modulating changes in the cellular redox state with a role in signalling, rather than cause oxidative damage to the cell.
Highlights
Stress memory in plants, known as stress imprint or priming, is considered to be an important component of the behavioral ecology of plants and it is becoming an increasingly important part of plant stress physiology textbooks nowadays
A number of Crassulacean acid metabolism (CAM) plants are extremely resistant to drought, as they are commonly adapted to deserts and other arid or semi-arid environments [19]
Phytohormones may be involved in plant response to reiterated drought stress in the invasive CAM plant, A. cordifolia
Summary
Known as stress imprint or priming, is considered to be an important component of the behavioral ecology of plants and it is becoming an increasingly important part of plant stress physiology textbooks nowadays. There is an increasing interest in stress memory effects, since. Drought Memory in Plants this feature has important implications in plant stress physiology [2]. The occurrence of stress memory, either leading to positive or negative effects in plant stress responses, and the mechanisms underlying stress memory are still very poorly understood [2]. A better knowledge on stress memory effects is urgently needed to better understand the physiology and ecology of plants, and to improve crop production and environmental management practices
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