Abiotic stress responses in plants: An overview

Abstract

Plants are more and more affected by environmental stresses, especially by the devastating consequences of desertification and water scarcity which can be seen and felt all over the world. About 3.6 billion of the world's 5.2 billion hectares of dryland used for agriculture have already suffered erosion, soil degradation, and salinization. Desertification can hinder efforts for sustainable development and introduces new threats to human health, ecosystems, and national economies. This problem is catalyzed by global climate change which exacerbates desertification and salinization. Therefore, solutions are desperately needed, such as the improvement of drought and salinity tolerance of crops, which in turn requires a detailed knowledge about tolerance mechanisms in plants. These mechanisms comprise a wide range of responses on molecular, cellular, and whole plant levels, which include amongst others the synthesis of compatible solutes/osmolytes and radical scavenging mechanisms. Regarding global change, elevated atmospheric CO2concentrations can enhance salt and drought tolerance because oxidative stress is alleviated and more energy can be provided for energy-dependent tolerance mechanisms such as the synthesis of compatible solutes and antioxidants, thus increasing the suitability of plants as crops in future. A detailed knowledge of the physiological and biochemical basis of drought and salt tolerance and its interaction with elevated CO2concentration can provide a basis for the cultivation of suitable plants in regions threatened by desertification and water scarcity under sustainable culture conditions. Even the drylands could offer tangible economic and ecological opportunities. The aim of this chapter is to uncover how compatible solutes and antioxidants alleviate environmental stress, especially drought and salt stress, and the role elevated CO2concentrations can play in this context, so that early indicators allowing successful breeding can be identified and the potential of plants as crops in a CO2rich world can be assessed.