Many organisms evolved strategies to survive desiccation. Plant seeds protect dehydrated embryos from various stressors and can lay dormant for millennia. Hydration is the key trigger to initiate germination, but the mechanism by which seeds sense water remains unresolved. We identified an uncharacterized Arabidopsis thaliana prion-like protein we named FLOE1, which phase separates upon hydration and allows the embryo to sense water stress. We demonstrate that biophysical states of FLOE1 condensates modulate its biological function in vivo in suppressing seed germination under unfavorable environments. We find intragenic, intraspecific, and interspecific natural variation in FLOE1 expression and phase separation and show that intragenic variation is associated with adaptive germination strategies in natural populations. This combination of molecular, organismal, and ecological studies uncovers FLOE1 as a tunable environmental sensor with direct implications for the design of drought-resistant crops, in the face of climate change.

许多生物进化出了在干燥环境中生存的策略。植物种子可以保护脱水的胚胎免受各种压力源的影响，并且可以休眠数千年。水合作用是启动发芽的关键触发因素，但种子感知水分的机制仍未解决。我们鉴定了一种未鉴定的拟南芥朊病毒样蛋白，我们将其命名为 FLOE1，该蛋白在水合时发生分离，并允许胚胎感知水分胁迫。我们证明了 FLOE1 缩合物的生物物理状态调节其在体内的生物学功能在不利环境下抑制种子发芽。我们发现 FLOE1 表达和相分离中的基因内、种内和种间自然变异，并表明基因内变异与自然种群中的适应性萌发策略相关。这种分子、有机体和生态学研究的结合揭示了 FLOE1 作为一种可调节的环境传感器，在面对气候变化时对抗旱作物的设计具有直接影响。