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. Author manuscript; available in PMC: 2022 Jun 17.
Published in final edited form as: Annu Rev Plant Biol. 2021 Mar 8;72:17–46. doi: 10.1146/annurev-arplant-081720-015238

Figure 4.

Figure 4

Examples of phase separation in plant biology. Plants use phase separation in the regulation of numerous fundamental plant growth and developmental processes. Nuclei are in purple; proteins of interest in blue. Nuclei appear blue when the protein of interest is diffusely in the nucleus. (a) FLOWERING CONTROL LOCUS A (FCA) forms subnuclear condensates and has been associated with regulation of flowering time in Arabidopsis (35). FLX-LIKE 2 (FLL2) (AT1G67170) regulates FCA condensate formation, and a recent study identified an FLL2 mutant that resulted in reduced FCA condensate formation and that had a delayed flowering phenotype, implicating FCA condensate formation in the regulation of flowering time (35). (b) NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) is involved in regulation of effector-triggered immunity and forms oligomers in the cytoplasm through intramolecular disulfide bonds when there is no oxidative stress (125). However, upon pathogen attack, intracellular redox changes result in an oligomer-to-monomer transition for NPR1, resulting in dispersion of cytoplasmic oligomers (125). (c) STT1 (At5G40160) and STT2 (At5G66055) mediate translocation of proteins in the chloroplast twin-arginine translocation (cpTat) pathway from the stroma to the thylakoid membranes via a phase separation–dependent mechanism (91). STT1 and STT2 form condensates within the chloroplast, and disruption of STT1 and STT2 phase separation results in disruption of cpTat substrate translocation across the stroma (91). (d) AUXIN RESPONSE FACTOR (ARF)7 and ARF19 are localized to the nucleus near the root tip but are localized to cytoplasmic condensates in the upper root, where cell growth has ceased (102). The localization of ARF7/ARF19 to cytoplasmic condensates attenuates auxin response in the upper root and is important for regulation of auxin responsiveness in the root (102). (e) PhyB photobodies are subnuclear condensates that form in response to red light (52). PhyB photobodies have been implicated in the regulation of the circadian clock, photomorphogenesis, and thermomorphogenesis (52). Abbreviations: C, chloroplast; N, nucleus.