State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, 712100, China.
Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA.
J Integr Plant Biol. 2022 Aug;64(8):1543-1559. doi: 10.1111/jipb.13310. Epub 2022 Jul 8.
To identify novel regulators of stem cell renewal, we mined an existing but little explored cell type-specific transcriptome dataset for the Arabidopsis root. A member of the TGA family of transcription factors, TGA8, was found to be specifically expressed in the quiescent center (QC). Mutation in TGA8 caused a subtle root growth phenotype, suggesting functional redundancy with other TGA members. Using a promoter::HGFP transgenic approach, we showed that all TGA factors were expressed in the root, albeit at different levels and with distinct spatial patterns. Mutant analyses revealed that all TGA factors examined contribute to root growth by promoting stem cell renewal, meristem activity, and cell elongation. Combining transcriptome analyses, histochemical assays, and physiological tests, we demonstrated that functional redundancy exists among members of clades II and V or those in clades I and III. These two groups of TGA factors act differently, however, as their mutants responded to oxidative stress differently and quantitative reverse transcription polymerase chain reaction assays showed they regulate different sets of genes that are involved in redox homeostasis. Our study has thus uncovered a previously unrecognized broad role and a mechanistic explanation for TGA factors in root growth and development.
为了鉴定干细胞更新的新调控因子，我们从现有的、但很少被探索的拟南芥根细胞类型特异性转录组数据集中进行挖掘。一个 TGA 家族的转录因子 TGA8 被发现特异性地在静止中心（QC）表达。TGA8 的突变导致了细微的根生长表型，这表明与其他 TGA 成员存在功能冗余。利用启动子::HGFP 转基因方法，我们表明所有的 TGA 因子都在根中表达，尽管表达水平不同，且具有不同的空间模式。突变分析表明，所有被检测的 TGA 因子都通过促进干细胞更新、分生组织活性和细胞伸长来促进根生长。通过转录组分析、组织化学测定和生理测试相结合，我们证明了在第二和第五组或第一和第三组的成员之间存在功能冗余。然而，这两组 TGA 因子的作用方式不同，因为它们的突变体对氧化应激的反应不同，定量逆转录聚合酶链反应（qRT-PCR）检测表明它们调节不同的基因集，这些基因涉及氧化还原稳态。因此，我们的研究揭示了 TGA 因子在根生长和发育中的一个以前未被认识的广泛作用和机制解释。
