About this Research Topic : Facing up to stressful conditions imposed by their environment that could affect their growth and their development throughout their life cycle, plants must be able to perceive, to process and to translate different stimuli into adaptive responses. From a human point of view, knowledge about plant stress response is also vital for the development of breeding and biotechnological strategies to improve stress tolerance in crops. Understanding the organism-coordinated responses involves fine description of the mechanisms occurring at the cellular and molecular level. These mechanisms involve numerous components that are organized into complex transduction pathways and networks, from signal perception to physiological responses. The major challenges of plant signaling is to understand what kind of signals do cells receive, how are these signals recognized and how do cells respond spatially and temporally to these signals to program a specific response at the organism level. Furthermore, signal transduction cascades involve a large array of molecular and cellular processes that are not restricted to a peculiar stimulus. This has been illustrated in several studies showing extensive cross-talk between signaling pathways. This Frontiers in Plant Science Research Topic will provide recent knowledge on the signaling pathways induced by abiotic and biotic environmental changes such as drought, temperature fluctuations, high salinity, cold, light, nutrient deprivation, pollutants or microbial and herbivory attacks. The main two objectives of this Research Topic are: 1. to give a general overview of the different signaling mechanisms (eg. post-translationnal mechanisms, signalling molecules, etc.) involved in stress response at the cellular level 2. to demonstrate how does the research on cell signalling will help to understand stress responses at the whole plant level (plant adaptation to drought, pathogen attacks, etc.). We welcome contributions including original research papers, short communications, reviews and methods focused on the different components of the signaling cascades (receptors/sensors, Ca2+, MAP Kinases, Nitric Oxide, Reactive Oxygen Species, ion fluxes, etc.) and their role under different stress conditions. We would appreciate articles that deal with recent findings on the role of original cellular processes such as epigenetic or small RNA, or on the role of intracellular compartmentation or retrograde signaling in stress responses. This Research Topic will also try to build a bridge between the molecular cell signal transduction cascades and the plant response at the whole organism level. Finally, we solicit papers reporting how network modeling can help to process the important quantity of data provided by high throughput “omics” techniques and how network modeling could help to decipher the complexity of cell signaling transduction cascade. Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.