Nemesio-Gorriz Miguel, Blair Peter B, Dalman Kerstin, Hammerbacher Almuth, Arnerup Jenny, Stenlid Jan, Mukhtar Shahid M, Elfstrand Malin
Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences Uppsala, Sweden.
Department of Biology, University of Alabama at Birmingham Birmingham, AL, USA.
Front Plant Sci. 2017 Mar 9;8:305. doi: 10.3389/fpls.2017.00305. eCollection 2017.
Transcription factors (TFs) forming MYB-bHLH-WDR complexes are known to regulate the biosynthesis of specialized metabolites in angiosperms through an intricate network. These specialized metabolites participate in a wide range of biological processes including plant growth, development, reproduction as well as in plant immunity. Studying the regulation of their biosynthesis is thus essential. While MYB (TFs) have been previously shown to control specialized metabolism (SM) in gymnosperms, the identity of their partners, in particular bHLH or WDR members, has not yet been revealed. To gain knowledge about MYB-bHLH-WDR transcription factor complexes in gymnosperms and their regulation of SW, we identified two bHLH homologs of TT8, six homologs of the MYB transcription factor TT2 and one WDR ortholog of TTG1 in Norway spruce. We investigated the expression levels of these genes in diverse tissues and upon treatments with various stimuli including methyl-salicylate, methyl-jasmonate, wounding or fungal inoculation. In addition, we also identified protein-protein interactions among different homologs of MYB, bHLH and WDR. Finally, we generated transgenic spruce cell lines overexpressing four of the Norway spruce TT2 homologs and observed differential regulation of genes in the flavonoid pathway and flavonoid contents.
已知形成MYB-bHLH-WDR复合物的转录因子（TFs）通过一个复杂的网络调节被子植物中特殊代谢产物的生物合成。这些特殊代谢产物参与广泛的生物学过程，包括植物生长、发育、繁殖以及植物免疫。因此，研究它们生物合成的调控至关重要。虽然之前已经证明MYB（TFs）可以控制裸子植物中的特殊代谢（SM），但其伙伴的身份，特别是bHLH或WDR成员，尚未揭示。为了了解裸子植物中的MYB-bHLH-WDR转录因子复合物及其对特殊代谢（SM）的调控，我们在挪威云杉中鉴定出了两个TT8的bHLH同源物、六个MYB转录因子TT2的同源物以及一个TTG1的WDR直系同源物。我们研究了这些基因在不同组织中的表达水平以及在水杨酸甲酯、茉莉酸甲酯、创伤或真菌接种等各种刺激处理后的表达情况。此外，我们还鉴定了MYB、bHLH和WDR不同同源物之间的蛋白质-蛋白质相互作用。最后，我们构建了过表达四个挪威云杉TT2同源物的转基因云杉细胞系，并观察到类黄酮途径中基因的差异调控和类黄酮含量的变化。
