Environmental conditions greatly impact plant growth and development. In the current context of both global climate change and land degradation, abiotic stresses usually lead to growth restriction limiting crop production. Plants have evolved to sense and respond to maximize adaptation and survival; therefore, understanding the mechanisms involved in the different converging signaling networks becomes critical for improving plant tolerance. In the last few years, several studies have shown the plant responses against drought and salinity, high and low temperatures, mechanical wounding, heavy metals, hypoxia, UV radiation, or ozone stresses. These threats lead the plant to coordinate a crosstalk among different pathways, highlighting the role of phytohormones and reactive oxygen and nitrogen species (RONS). In particular, plants sense these reactive species through post-translational modification (PTM) of macromolecules such as nucleic acids, proteins, and fatty acids, hence triggering antioxidant responses with molecular implications in the plant welfare. Here, this review compiles the state of the art about how plant systems sense and transduce this crosstalk through PTMs of biological molecules, highlighting the S-nitrosylation of protein targets. These molecular mechanisms finally impact at a physiological level facing the abiotic stressful traits that could lead to establishing molecular patterns underlying stress responses and adaptation strategies.

Seed germination and seedling establishment are complex traits regulated by post-translational modifications, which converge on key molecular devices such as the bZIP transcription factor ABSCISIC ACID-INSENSITIVE 5 (ABI5). This represents a molecular hub in the abscisic acid signaling pathway, which represses seed germination and seedling establishment. ABI5 is post-translationally modified by nitric oxide through Cys153-specific S-nitrosylation (SNO), leading to its degradation. Despite the physiological effects of redox-sensitive proteins, the specificity and molecular mechanisms underlying this type of regulation during seed germination and post-germination developmental checkpoints remain unknown. Here, we show the effect of the redox environment on the formation of ABI5 complexes, highlighting the relevance of Cys153. Mutation of this key residue and the phosphorylation status influence the subcellular localization of ABI5. We establish an enzymatic system underlying the recently determined reversibility of SNO mediated by thioredoxin h5 (TRXh5). Furthermore, seeds overexpressing the redoxins ROXY10 and ROXY21 show a misregulation in germination and in the accumulation of the ABI5 protein. These results provide a physiological link between redox regulation and the abscisic acid signaling pathway through the control of ABI5 that is crucial for a successful seedling establishment.