Principles of signal integration in combinatorial stress acclimatization.

Plants efficiently acclimatize to their environment despite experiencing varied combinations of chemical and physical parameters during their life cycle. The order of appearance, intensity and duration of relevant environmental factors, the developmental state of the plants and the cell type and organ exposed to the environmental cues add additional layers of complexity. The combinatorial diversity of environmental cues and their interaction with plants tentatively approach infinity. Beyond certain thresholds, the deviation of single or multiple environmental factors from their optimum challenges the homeostatic system to such an extent that the plants are forced into a state of stress. Given the finite complexity of genomes, response programmes to acclimatize or genetically adapt to the environment must have additional mechanisms of input integration beyond the specific detection of abiotic and biotic stress stimuli by receptors and sensors. The response to combinatorial stress parameters can be synergistic, antagonistic or indifferent and is often unpredictable from the response to single stressors. The physiological response features must have a mechanistic reflection at the molecular level. Central elements in signal processing may act as hubs of signal integration in this process, and crosstalk between signalling networks may dampen or enhance the output to the response generator system(s).This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.