Main Conclusion GbMYBR1, a new type of R2R3-MYB repressor from Ginkgo biloba, displayed pleiotropic effects on plant growth, phenylpropanoid accumulation, by regulating multiple related genes at different levels. Abstract Ginkgo biloba is a typical gymnosperm that has been thriving on earth for millions of years. MYB transcription factors (TFs) play important roles in diverse processes in plants. However, the role of MYBs remains largely unknown in Ginkgo. Here, an MYB TF gene from Ginkgo, designated as GbMYBR1, was found to act as a repressor in multiple processes. GbMYBR1 was mainly expressed in the leaves of Ginkgo. Over-expression of GbMYBR1 in Arabidopsis thaliana led to growth retardation, decreases in lignin content, reduced trichome density, and remarkable reduction in anthocyanin and flavonol contents in leaves. Proanthocyanidin content was decreased in the seeds of transgenic Arabidopsis, which led to light-brown seed color. Both qPCR and transcriptome sequencing analyses demonstrated that the transcript levels of multiple genes related to phenylpropanoid biosynthesis, trichome formation, and pathogen resistance were down-regulated in the transgenic Arabidopsis. In particular, we found that GbMYBR1 directly interacts with the bHLH cofactor GL3 as revealed by yeast two-hybrid assays. Our work indicated that GbMYBR1 has pleiotropic effects on plant growth, phenylpropanoid accumulation, and trichome development, mediated by interaction with GL3 or direct suppression of key pathway genes. Thus, GbMYBR1 represents a novel type of R2R3 MYB repressor. Electronic supplementary material The online version of this article (10.1007/s00425-020-03476-1) contains supplementary material, which is available to authorized users.

中文翻译：

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来自银杏的 GbMYBR1 抑制拟南芥中苯丙烷的生物合成和毛状体发育

主要结 摘要 银杏是一种典型的裸子植物，已在地球上繁衍生息了数百万年。MYB 转录因子 (TFs) 在植物的不同过程中发挥着重要作用。然而，MYBs 在银杏中的作用仍然很大程度上未知。在这里，来自银杏的 MYB TF 基因被命名为 GbMYBR1，被发现在多个过程中充当阻遏物。GbMYBR1主要在银杏叶中表达。GbMYBR1在拟南芥中的过表达导致生长迟缓，木质素含量降低，毛状体密度降低，叶片中花青素和黄酮醇含量显着降低。转基因拟南芥种子中原花青素含量降低，导致种子呈浅棕色。qPCR 和转录组测序分析均表明，与苯丙素类生物合成、毛状体形成和病原体抗性相关的多个基因的转录水平在转基因拟南芥中下调。特别是，我们发现 GbMYBR1 直接与 bHLH 辅因子 GL3 相互作用，正如酵母双杂交试验所揭示的那样。我们的工作表明，GbMYBR1 通过与 GL3 相互作用或直接抑制关键途径基因介导，对植物生长、苯丙素积累和毛状体发育具有多效性。因此，GbMYBR1 代表一种新型的 R2R3 MYB 阻遏物。电子补充材料本文网络版（10.