NFXL1 functions as a transcriptional activator required for thermotolerance at reproductive stage in Arabidopsis,Journal of Integrative Plant Biology

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NFXL1 functions as a transcriptional activator required for thermotolerance at reproductive stage in Arabidopsis
Journal of Integrative Plant Biology ( IF 9.3 ) Pub Date : 2023-12-23 , DOI: 10.1111/jipb.13604
Qiao-Yun Zhu ₁ , Lin-Lin Zhang ₁ , Jian-Xiang Liu ₁

Affiliation

Plants are highly susceptible to abiotic stresses, particularly heat stress during the reproductive stage. However, the specific molecular mechanisms underlying this sensitivity remain largely unknown. In the current study, we demonstrate that the Nuclear Transcription Factor, X-box Binding Protein 1-Like 1 (NFXL1), directly regulates the expression of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN 2A (DREB2A), which is crucial for reproductive thermotolerance in Arabidopsis. NFXL1 is upregulated by heat stress, and its mutation leads to a reduction in silique length (seed number) under heat stress conditions. RNA-Seq analysis reveals that NFXL1 has a global impact on the expression of heat stress responsive genes, including DREB2A, Heat Shock Factor A3 (HSFA3) and Heat Shock Protein 17.6 (HSP17.6) in flower buds. Interestingly, NFXL1 is enriched in the promoter region of DREB2A, but not of either HSFA3 or HSP17.6. Further experiments using electrophoretic mobility shift assay have confirmed that NFXL1 directly binds to the DNA fragment derived from the DREB2A promoter. Moreover, effector–reporter assays have shown that NFXL1 activates the DREB2A promoter. The DREB2A mutants are also heat stress sensitive at the reproductive stage, and DEREB2A is epistatic to NFXL1 in regulating thermotolerance in flower buds. It is known that HSFA3, a direct target of DREB2A, regulates the expression of heat shock proteins genes under heat stress conditions. Thus, our findings establish NFXL1 as a critical upstream regulator of DREB2A in the transcriptional cassette responsible for heat stress responses required for reproductive thermotolerance in Arabidopsis.

中文翻译：

NFXL1 作为拟南芥繁殖阶段耐热性所需的转录激活剂

植物极易受到非生物胁迫，特别是生殖阶段的热胁迫。然而，这种敏感性背后的具体分子机制仍然很大程度上未知。在当前的研究中，我们证明核转录因子 X-box 结合蛋白 1-Like 1 (NFXL1) 直接调节脱水响应元件结合蛋白2A (DREB2A) 的表达，这对于生殖耐热性至关重要。拟南芥。 NFXL1受热应激上调，其突变导致热应激条件下长角果长度（种子数量）减少。 RNA-Seq分析表明，NFXL1对花蕾中热应激反应基因的表达具有全局影响，包括DREB2A 、热休克因子A3 （ HSFA3 ）和热休克蛋白17.6 （ HSP17.6 ）。有趣的是，NFXL1 在DREB2A的启动子区域富集，但在HSFA3或HSP17.6的启动子区域不富集。使用电泳迁移率变动分析的进一步实验已证实 NFXL1 直接结合源自DREB2A启动子的 DNA 片段。此外，效应-报告基因检测表明 NFXL1 激活DREB2A启动子。 DREB2A突变体在繁殖阶段也对热应激敏感，并且DEREB2A在调节花芽耐热性方面比NFXL1上位。已知HSFA3是DREB2A的直接靶标，在热应激条件下调节热休克蛋白基因的表达。因此，我们的研究结果表明 NFXL1 是转录盒中DREB2A的关键上游调节因子，负责拟南芥生殖耐热性所需的热应激反应。

更新日期：2023-12-23

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