Phytohormonal regulation of α-tocopherol in plants

Abstract

Alpha-tocopherol (α-tocopherol), a major member of the tocochromanol family, plays a crucial role in scavenging reactive oxygen species generated during photosynthesis. Recent studies have revealed additional roles of α-tocopherol in metabolic processes, development, and stress responses, indicating its complex interaction with plant phytohormones. However, the metabolism and hormonal regulation of α-tocopherol under normal or stressful conditions has not been thoroughly investigated. Furthermore, the molecular and biochemical regulation of α-tocopherol in different plant organs in response to biotic or abiotic stress, and its hormonal regulation, have received less attention. The aim of this review is to assess and summarize the existing literature in order to better understand the biosynthesis and role of α-tocopherol mediated by phytohormones. Based on these data, the amount of α-tocopherol changes not only in photosynthesising leaves, but also during fruit ripening and in roots, seed development and germination (in the dark), which is influenced by many hormones such as auxin, cytokinins, abscisic acid and ethylene. In addition, the levels of defense hormones such as salicylic acid, ethylene or abscisic acid are higher in several vte mutants, further demonstrating the close relationship between the regulation of tocopherol metabolism and phytohormones. These interactions have the potential to influence key biological processes such as growth, development and various stress responses. By summarising current knowledge, this review highlights the multiple roles of α-tocopherol and provides evidence linking α-tocopherol metabolism and phytohormone signaling. Understanding these interactions may provide alternative ways to enhance plant defense responses and productivity through biotechnology and agricultural practices.