Abiotic stress, stress combinations and crop improvement potential

This is the authors' abstract. We don't add key points for this paper.

Plants have a remarkable capacity to occupy ecological niches that are shaped by their edaphic, climatic and biotic environments with extremes that have cyclic patterns, occur very infrequently or heterogeneously, or are chronic. Natural genetic variation for adaptation and acclimation mechanisms provide this inherent ecological niche capacity. This variation and subsequent induced variation, has been responsible for plant domestication and agricultural development that has changed civilization and now sustains global world population and its inordinate growth. Substantial research progress with regard to plant stress adaptation and acclimation mechanisms over the last couple of decades has led to a fundamental understanding of basic genetic and environmental interactions that are critical for natural plant fitness and crop yield stability. Critical determinants have been identified and translational examples beneficial for human food production are occurring. Plant research dedicated to the understanding of mechanisms allowing plant to adjust to environmental constraints is amongst the most significant research domains both in quantity and quality. For instance, out of the 11 original articles of a recent issue of The Plant Journal (Vol. 90, Issue 1, April 2017), six manuscripts specifically studied (or at least considered subsequent) interactions with the physical environment. More generally, during 2016, The Plant Journal received more than 180 submissions that included reference to 'abiotic' and/or 'stress'. In this special issue section, five reviews are presented. The first three reviews especially highlight the complexity of plant response to stresses, and combinations of stresses (a point of particular recent attention). The last three reviews also describe how stress tolerance knowledge is used to improve crops. Zhang and Sonnewald (2017) describe in detail plant responses to stress at the transcriptional, metabolic and physiological levels and emphasize the main recent findings in comparing these responses to combinations (concomittant or sequential) of environmental constraints. They focus particularly on water and temperature-related constraints, and interactions with biotic factors, and highlight the specificities of combined stress response. Then, Choudhury et al. (2017) focus on the role of reactive oxygen species (ROS) in plant response to abiotic stress. They describe the metabolic and signaling role of ROS and how the plant and cell may integrate signals through different ROS signatures. Finally, they review recent litterature on the emerging role of ROS in acclimation of plants to stress combinations. Heuer et al. (2017) gather expertise from six different labs to draw an updated picture of phosphorus (P) use efficiency in plants, and its interactions with aluminum toxicity. This combines genetics and physiological knowledge about the regulations of P metabolism in plants, leading to several possible mode of action under study in different crop systems such as rice and barley. Not only genetics and physiology, but also their combination with agronomy and biotechnology is covered, with the recent idea of exploiting phosphite fertilisation. Ainsworth (2017) then describes global plant response to ground-level ozone pollutant. Beyond the plant molecular signaling pathways depicted, the genetics of the tolerance to this compound in model (Arabidopsis) and crop systems (particularly rice) is improving. One intriguing feature here, is the described lack of translation of laboratory experiments to the field. Gilliham et al. (2017) review more generally the potential for translation in plant breeding programmes from knowledge gained at the level of the basic mechanisms of tolerance to abiotic stress. Taking specific examples, particularly in the domains of water-use efficiency and salinity tolerance, we learn of the history of successful translation events. By noting the inherent complexity in combining research goals and plant breeding strategies, the authors indicate where we might put future research and funding efforts. It is an exciting time for stress-related biology, with the discovery of many structural components of the pathways for stress responses and the disclosure of much intra- and inter-specific variation for those interactions with the environment. High-throughput phenotyping is also starting to change our ability to study interactions between different constraints, previously difficult to harness especially in combination. We think it is an opportune moment to gather the views of some of the best specialists' on plant and abiotic stress to emphasize contemporary research and prospects for the near future that will sustain plant ecosystems and advance crop production – both of which are under tremendous pressures because of global climate change and population demands.