Abstract: Developmental noise (DN) is random phenotypic variation often estimated by fluctuating asymmetry (FA), which is considered a biomarker of environmental stress. However, data on DN/FA stress responses in plants, including woody ones, are contradictory. This analysis examines DN stress reactions in plants in terms of the hormesis concept (low-dose stimulation and high-dose inhibition). It is shown that various low-dose stressors (environmental-related impacts, pollutants and even biotic factors) causing hormesis reduce DN/FA levels, demonstrating the plant’s ability to actively control DN through regulatory mechanisms. It is hypothesized that this DN regulation can be potentially based on the control of the reactive oxygen species (ROS) production, since ROS regulate growth, development, and stress responses in all aerobic organisms. Excessive ROS during stress causes biomolecule oxidation and fluctuations in cellular processes, including developmental gene expression, thereby increasing DN/FA levels. Hormesis may reduce DN levels by overactivating transcription factors of antioxidant enzyme genes. DN stress sensitivity, including its ability to hormesis, depends some important aspects that are often overlooked: the functional importance and complexity of the trait, the trait selection history, the trait developmental plasticity, the species ecological strategy, the development stage, and trade-offs. The significant complexity of DN stress responses requires using a set of traits to assess DN/FA, instead of a single trait, along with physiological and biochemical plant stress indicators to identify trade-offs. New approaches to environmental stress indication based on DN/FA levels are needed, which count hormesis and trade-offs. Hormesis can increase fitness by reducing DN levels of functionally significant traits. Thus, hormesis may be a mechanism for regulating the trajectory of trait development by controlling DN levels with stressful environments.

Key words: Fluctuating asymmetry, Developmental instability, Environmental stress, Reactive oygen Species, Biomarker