Fig. 2: PrLD of FUST1 is the main driver for heat sensing and condensation.

a Top, illustration of the amino acid composition of PrLD. Middle, protein domain structure of FUST1. Bottom, prediction of the IDRs and prion-like domain by PONDR and PLACC algorithms. b Representative confocal microscopic images of tobacco epidermal cells expressing FUST1 and its variants. The cells were treated at 37 °C for 30 min and 22 °C as control. Scale bars, 10 μm. c In vitro phase separation assay of Cy5-labeled PrLD^WT at different temperatures and concentrations. Scale bar, 5 μm. d Phase diagram of PrLD^WT as a function of temperature. Red dots, with detectable condensates. Empty circles, without detectable condensates. e, f Temperature-dependent turbidity of indicated proteins with indicated protein concentrations. In vitro phase separation assay in c and turbidity measurements in e, f were conducted in 40 mM Tris-HCl pH, 7.4 and 500 mM NaCl. Error bars indicate mean ± SD (n = 3). g Representative confocal microscopic images of Arabidopsis root tip cells expressing FUST1, FUST1^∆PrLD and FUST1^{PrLD Y>S}. The roots were treated at 35 °C for 30 min. Scale bars, 10 μm. h Statistical analysis of number of condensates per cell in each genotype in g at 35 °C. Error bars indicate mean ± SD (n = 15). P values were calculated using two-sided Student’s t-test. ****P < 0.0001.