Abiotic stress response in plants: When post-transcriptional and post-translational regulations control transcription

The molecular response of plants to abiotic stresses has been often considered as a complex process mainly based on the modulation of transcriptional activity of stress-related genes. Nevertheless, recent findings have suggested new layers of regulation and complexity. Upstream molecular mechanisms are involved in the plant response to abiotic stress, above all in the regulation of timings and amount of specific stress responses. Post-transcriptional mechanisms based on alternative splicing and RNA processing, as well as RNA silencing define the actual transcriptome supporting the stress response. Beyond protein phosphorylation, other post-translational modifications like ubiquitination and sumoylation regulate the activation of pre-existing molecules to ensure a prompt response to stress. In addition, cross-connections exist among these mechanisms, clearly demonstrating further and superimposed complexity levels in the response to environmental changes. Even if not widely identified, the targets of these mechanisms characterised so far are mainly regulatory elements of the stress response pathways. The network of post-transcriptional and post-translational modifications ensures temporally and spatially appropriate patterns of downstream stress-related gene expression. Future attempts of plant engineering could exploit insights from a deeper comprehension of these emerging sites of regulation of stress responses to develop stress resistant plants. (C) 2008 Elsevier Ireland Ltd. All rights reserved.