Role of ubiquitination enzymes in abiotic environmental interactions with plants

1. Introduction 494 2. Ubiquitin system in plants 495 2.1. Ubiquitin and ubiquitination 495 2.2. Ubiquitin activating enzyme (E1) and ubiquitin conjugating enzyme (E2) 496 2.3. Ubiquitin ligase enzyme (E3) 496 2.4. Deubiquitinating enzymes 496 2.5. 26S proteasomal complex 496 3. Ubiquitination in abiotic stress responses 496 3.1. Ubiquitin conjugating enzyme in abiotic stress responses 496 3.2. Ubiquitin ligases in abiotic stress responses 498 3.2.1. ABA-dependent stress responses to drought and salinity stress 498 3.2.2. ABA-independent stress responses to drought and salinity stress 499 3.2.3. Stress responses to temperature 500 Ubiquitination, a post-translational modification, plays a crucial role in various aspects of plant development and stress responses. Protein degradation by ubiquitination is well established and ubiquitin is the main underlying component directing the turnover of proteins. Recent reports have also revealed the non-proteolytic roles of ubiquitination in plants. In the past decade, ubiquitination has emerged to be one of the most important players in modulating plant's responses to abiotic stresses, which led to identification of specific E3 ligases and their targets involved in the process. Most of the E3 ligases play regulatory roles by modifying the stability and accumulation of stress responsive regulatory proteins, such as transcription factors, thus, modifying the downstream responses, or by degrading the proteins involved in the downstream cascade itself. In this review, we summarize and highlight the recent advances in the field of ubiquitination-mediated regulation of plant's responses to various abiotic stresses including limited nutrient availability and metal toxicity. The non-proteolytic role of ubiquitination in epigenetic regulation of abiotic stress induced response has also been discussed. (c) 2021 Elsevier B.V. All rights reserved.