State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, 26 Hexing Road, Harbin, China.
Tree Physiol. 2019 Jun 1;39(6):1046-1060. doi: 10.1093/treephys/tpz021.
Flowering is a crucial process for plants that is under complex genetic control. AP1 acts as an organizer and a switch for the transition from vegetative to reproductive growth. In our previous study, we found that overexpression of BpAP1 significantly promoted the formation of male inflorescence in birch (Betula platyphlla × B. pendula). In this study, we aimed at investigating the molecular regulatory mechanism of BpAP1 during the process of male inflorescence formation in birch. We found that overexpression of BpAP1 affected the expression of many flowering-related genes, and had significant effect on B class MADS-box genes. A BpAP1-mediated gene regulatory network was constructed and B class gene BpDEF was finally predicted as a key target gene of BpAP1. Chromatin immunoprecipitation results indicated that BpAP1 could directly regulate BpDEF during the process of male inflorescence formation. Yeast one-hybrid assays and its validation in tobacco results suggested that BpAP1 regulated BpDEF via binding to a consensus DNA sequence known as CArG box. Gene function analysis of BpDEF indicated that BpDEF may function in sex-determination, and in particular specify the identity of male inflorescence in birch. Our results provide valuable clues for our understanding of the molecular mechanism of BpAP1 during the process of male inflorescence formation in birch.
开花是植物的一个关键过程，受复杂的遗传控制。AP1 作为一个组织者和开关，促进了从营养生长到生殖生长的转变。在我们之前的研究中，我们发现过量表达 BpAP1 显著促进了桦树（Betula platyphlla × B. pendula）雄性花序的形成。在这项研究中，我们旨在研究 BpAP1 在桦树雄性花序形成过程中的分子调控机制。我们发现，过量表达 BpAP1 影响了许多与开花相关基因的表达，对 B 类 MADS-box 基因有显著影响。构建了一个 BpAP1 介导的基因调控网络，最终预测 B 类基因 BpDEF 是 BpAP1 的关键靶基因。染色质免疫沉淀结果表明，BpAP1 可以在雄性花序形成过程中直接调控 BpDEF。酵母单杂交实验及其在烟草中的验证结果表明，BpAP1 通过与称为 CArG 盒的保守 DNA 序列结合来调节 BpDEF。BpDEF 的基因功能分析表明，BpDEF 可能在性别决定中起作用，特别是在桦树中特异性指定雄性花序的身份。我们的研究结果为我们理解 BpAP1 在桦树雄性花序形成过程中的分子机制提供了有价值的线索。
