Stress Granules: Synthesis and Significance

Stress granules as indicated by name, are transient cytoplasmic structures formed in response to different kinds of stresses. These are found in various eukaryotic organisms with an aim to regulate expression of mRNAs as and when required. Being sessile in nature, plants have given more emphasis on post-transcriptional and translational regulation of gene expression so as to respond quickly to the stressful environment. Also, by virtue of their existence in the form of ribonucleoprotein complexes that possess all the potential to initiate translation, they help the cells to recover from stressful conditions rapidly. The basic constituents of stress granules are mRNA and proteins. These granules are formed by liquid–liquid phase separation and do not possess membranes. Nevertheless, their organized structure is a brief illustration of their functional significance. They comprise a shell consisting of untranslated mRNAs, transcription factors, and enzymes; and a core consisting of translation-related proteins with RNA-binding domains. During stress, when the cellular dynamics is disturbed, they act as important centers for storage, translational stalling, and degradation of mRNAs. This chapter discusses structural attributes of stress granules, dynamics of their assembly and disassembly, and their role in diverse plant stresses.