Heat stress induces misfolded protein accumulation in endoplasmic reticulum (ER), which initiates the unfolded protein response (UPR) in plants. Previous work has demonstrated the important role of a rice ER membrane-associated transcription factor OsbZIP74 (also known as OsbZIP50) in UPR. However, how OsbZIP74 and other membrane-associated transcription factors are involved in heat stress tolerance in rice is not reported. In the current study, we discovered that OsNTL3 is required for heat stress tolerance in rice. OsNTL3 is constitutively expressed and up-regulated by heat and ER stresses. OsNTL3 encodes a NAC transcription factor with a predicted C-terminal transmembrane domain. GFP-OsNTL3 relocates from plasma membrane to nucleus in response to heat stress and ER stress inducers. Loss-of-function mutation of OsNTL3 confers heat sensitivity while inducible expression of the truncated form of OsNTL3 without the transmembrane domain increases heat tolerance in rice seedlings. RNA-Seq analysis revealed that OsNTL3 regulates the expression of genes involved in ER protein folding and other processes. Interestingly, OsNTL3 directly binds to OsbZIP74 promoter and regulates its expression in response to heat stress. In turn, up-regulation of OsNTL3 by heat stress is dependent on OsbZIP74. Thus, our work reveals the important role of OsNTL3 in thermotolerance, and a regulatory circuit mediated by OsbZIP74 and OsNTL3 in communications among ER, plasma membrane and nucleus under heat stress conditions.

中文翻译：

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膜相关的NAC转录因子OsNTL3与水稻的耐热性有关。

热应激会引起内质网（ER）中错误折叠的蛋白质积累，从而引发植物中未折叠的蛋白质反应（UPR）。先前的工作证明了水稻ER膜相关转录因子OsbZIP74（也称为OsbZIP50）在UPR中的重要作用。但是，尚未报道OsbZIP74和其他膜相关转录因子如何参与水稻的热胁迫耐受性。在当前的研究中，我们发现OsNTL3是水稻耐热胁迫的必需物质。OsNTL3在热量和内质网应激中组成性表达并上调。OsNTL3编码具有预测的C端跨膜结构域的NAC转录因子。GFP-OsNTL3响应热应激和ER应激诱导剂而从质膜迁移到细胞核。OsNTL3的功能丧失突变赋予热敏感性，而无跨膜结构域的截短形式的OsNTL3的可诱导表达提高了水稻幼苗的耐热性。RNA-Seq分析显示，OsNTL3调节与ER蛋白折叠和其他过程有关的基因的表达。有趣的是，OsNTL3直接与OsbZIP74启动子结合并响应热应激调节其表达。反过来，热应力对OsNTL3的上调取决于OsbZIP74。因此，我们的工作揭示了OsNTL3在耐热性中的重要作用，以及由OsbZIP74和OsNTL3介导的调节电路在热应激条件下在ER，质膜和核之间的通讯中。RNA-Seq分析显示，OsNTL3调节与ER蛋白折叠和其他过程有关的基因的表达。有趣的是，OsNTL3直接与OsbZIP74启动子结合并响应热应激调节其表达。反过来，热应力对OsNTL3的上调取决于OsbZIP74。因此，我们的工作揭示了OsNTL3在耐热性中的重要作用，以及由OsbZIP74和OsNTL3介导的调节电路在热应激条件下在ER，质膜和核之间的通讯中。RNA-Seq分析显示，OsNTL3调节与ER蛋白折叠和其他过程有关的基因的表达。有趣的是，OsNTL3直接与OsbZIP74启动子结合并响应热应激调节其表达。反过来，热应力对OsNTL3的上调取决于OsbZIP74。因此，我们的工作揭示了OsNTL3在耐热性中的重要作用，以及由OsbZIP74和OsNTL3介导的调节电路在热应激条件下在ER，质膜和核之间的通讯中。