As a key integrator of shoot branching, BRANCHED 1 (BRC1) coordinates and is orchestrated by endogenous and environmental signals involved in the regulation of axillary bud outgrowth. In the present study, we characterized the regulatory roles of five BRC gene members in tobacco (Nicotiana tabacum L.) using CRISPR site-directed mutagenesis and overexpression assays. It was shown that lateral branching was negatively regulated by NtBRC1A-1, 1B-1, and 1B-2, but was unexpectedly promoted by NtBRC2A. Suppression of bud growth may be attained by direct binding of NtBRCs to the Tassels Replace Upper Ears 1 (TRU1) genes. It was speculated that NtBRC2A probably confers a dominant negative effect by interfering with the branching-inhibitory BRC1 genes. Our results suggested that highly homologous gene family members may function antagonistically in the same signaling pathway. However, the molecular mechanism underlying NtBRC2A-mediated outgrowth of axillary buds needs to be further addressed. KEY MESSAGE: Axillary bud outgrowth in general is negatively regulated by the BRANCHED gene. Here we show that the BRANCHED genes play opposing regulatory roles in tobacco lateral branching.

中文翻译：

---

烟草中的BRANCHED基因拮抗腋芽的生长。

作为枝条分支的重要整合者，BRANCHED 1（BRC1）协调并由参与调节腋芽生长的内源性和环境信号进行协调。在本研究中，我们使用CRISPR定点诱变和过表达测定法表征了五个BRC基因成员在烟草（Nicotiana tabacum L.）中的调控作用。结果表明，横向分支受NtBRC1A-1、1B-1和1B-2负调控，但出乎意料地由NtBRC2A促进。NtBRC与流苏替换上耳1（TRU1）基因的直接结合可以抑制芽的生长。据推测，NtBRC2A可能通过干扰分支抑制性BRC1基因而赋予显性负作用。我们的结果表明，高度同源的基因家族成员可能在同一信号通路中具有拮抗作用。然而，NtBRC2A介导的腋芽生长的分子机制需要进一步解决。关键信息：腋芽的生长通常受BRANCHED基因的负调控。在这里，我们显示了BRANCHED基因在烟草横向分支中起相反的调节作用。