As sessile organisms, plants have evolved numerous strategies to acclimate to changes in environmental temperature. However, the molecular basis of this acclimation remains largely unclear. In this study we identified a tRNA^His guanylyltransferase, AET1, which contributes to the modification of pre-tRNA^His and is required for normal growth under high-temperature conditions in rice. Interestingly, AET1 possibly interacts with both RACK1A and eIF3h in the endoplasmic reticulum. Notably, AET1 can directly bind to OsARF mRNAs including the uORFs of OsARF19 and OsARF23, indicating that AET1 is associated with translation regulation. Furthermore, polysome profiling assays suggest that the translational status remains unaffected in the aet1 mutant, but that the translational efficiency of OsARF19 and OsARF23 is reduced; moreover, OsARF23 protein levels are obviously decreased in the aet1 mutant under high temperature, implying that AET1 regulates auxin signaling in response to high temperature. Our findings provide new insights into the molecular mechanisms whereby AET1 regulates the environmental temperature response in rice by playing a dual role in tRNA modification and translational control.

作为固着生物，植物已经进化出许多策略来适应环境温度的变化。但是，这种适应的分子基础仍然不清楚。在这项研究中，我们确定了一个tRNA ^His鸟嘌呤基转移酶AET1，它有助于对pre-tRNA ^His的修饰，并且是水稻在高温条件下正常生长所必需的。有趣的是，AET1可能与内质网中的RACK1A和eIF3h相互作用。值得注意的是，AET1可以直接结合OsARF mRNA，包括OsARF19和OsARF23的uORF。，表示AET1与翻译规则相关联。此外，多核糖体谱分析表明，aet1突变体的翻译状态不受影响，但是OsARF19和OsARF23的翻译效率却降低了。此外，高温下的aet1突变体中OsARF23蛋白水平明显降低，这表明AET1在高温下调节生长素信号传导。我们的发现为AET1通过在tRNA修饰和翻译控制中发挥双重作用调节水稻环境温度响应的分子机制提供了新的见解。