High temperature is one of the major environmental stresses affecting plant growth and fitness. Heat stress transcription factors (HSFs) play critical roles in regulating the expression of heat-responsive genes. However, how HSFs are regulated remains obscure. Here, we show that ALBA4, ALBA5 and ALBA6, which phase separate into stress granules (SGs) and processing bodies (PBs) under heat stress, directly bind selected messenger RNAs, including HSF mRNAs, and recruit them into SGs and PBs to protect them from degradation under heat stress in Arabidopsis. The alba456 triple mutants, but not single and double mutants, display pleiotropic developmental defects and hypersensitivity to heat stress. Mutations in XRN4, a cytoplasmic 5′ to 3′ exoribonuclease, can rescue the observed developmental and heat-sensitive phenotypes of alba456 seedlings. Our study reveals a new layer of regulation for HSFs whereby HSF mRNAs are stabilized by redundant action of ALBA proteins in SGs and PBs for plant thermotolerance.

高温是影响植物生长和健康的主要环境胁迫之一。热应激转录因子 (HSFs) 在调节热反应基​​因的表达中起关键作用。然而，如何监管HSF仍不清楚。在这里，我们展示了 ALBA4、ALBA5 和 ALBA6，它们在热应激下相分离成应力颗粒 (SGs) 和加工体 (PBs)，直接结合选定的信使 RNA，包括HSF mRNA，并将它们招募到 SG 和 PB 中以保护它们拟南芥热 胁迫 下 的 降解. alba456三重突变体，但不是单突变体和双突变体，表现出多效性发育缺陷和对热应激的过敏反应。XRN4中的突变，一种细胞质 5' 到 3' 外切核糖核酸酶，可以挽救观察到的alba456幼苗的发育和热敏感表型。我们的研究揭示了 HSFs 的新调控层，其中 HSF mRNAs通过SGs 和 PBs 中 ALBA 蛋白的冗余作用来稳定植物耐热性。