Nguyen Thu-Hien, Kim Min Jung, Kim Jungmook
Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, South Korea.
Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, South Korea.
Plant Physiol. 2024 Dec 2;196(4):2463-2475. doi: 10.1093/plphys/kiae448.
The intricate regulation of gene expression determining cell fate during male gametogenesis involves a complex interplay of multiple transcriptional regulators. In Arabidopsis (Arabidopsis thaliana), the LATERAL ORGAN BOUNDARIES DOMAIN 10 (LBD10) transcription factor is prominent in early microspores and both the germ and vegetative cells of bicellular pollen, playing an important role in pollen development. However, in mature pollen, LBD10 exclusively localizes in the vegetative cell nucleus (VCN). Here, we identify cis-acting elements and trans-acting factors responsible for the specific expression of LBD10 in the VCN during pollen maturation. Using a series of LBD10 promoter deletion constructs fused with GUS or GFP reporters, we pinpoint two crucial core promoter sequences. These sequences are situated within two 200 bp regions upstream of the start codon and independently govern LBD10 expression in the VCN. We demonstrate that a W-box motif (AGTCAC) at -770 bp is essential for activating the expression of LBD10 in vegetative cells during pollen maturation. Our transient gene expression assays using Arabidopsis protoplasts and chromatin immunoprecipitation assays show that the transcription factors WRKY2 and WRKY34 recognize the LBD10 promoter region containing W-box motifs. Collectively, our findings suggest that WRKY2 and WRKY34 binding to the W-box motifs plays a role in the VCN-specific expression of LBD10 in pollen. This interaction may contribute to male gametophyte development, shedding light on the intricate regulatory network governing this critical biological process.
在雄配子发生过程中，决定细胞命运的基因表达的复杂调控涉及多种转录调节因子的复杂相互作用。在拟南芥中，侧生器官边界结构域10（LBD10）转录因子在早期小孢子以及二细胞花粉的生殖细胞和营养细胞中都很突出，在花粉发育中起重要作用。然而，在成熟花粉中，LBD10仅定位于营养细胞核（VCN）。在这里，我们鉴定了负责花粉成熟过程中LBD10在VCN中特异性表达的顺式作用元件和反式作用因子。使用一系列与GUS或GFP报告基因融合的LBD10启动子缺失构建体，我们确定了两个关键的核心启动子序列。这些序列位于起始密码子上游的两个200 bp区域内，并独立控制LBD10在VCN中的表达。我们证明，位于-770 bp处的W-box基序（AGTCAC）对于激活花粉成熟过程中营养细胞中LBD10的表达至关重要。我们使用拟南芥原生质体进行的瞬时基因表达分析和染色质免疫沉淀分析表明，转录因子WRKY2和WRKY34识别含有W-box基序的LBD10启动子区域。总体而言，我们的研究结果表明，WRKY2和WRKY34与W-box基序的结合在花粉中LBD10的VCN特异性表达中起作用。这种相互作用可能有助于雄配子体发育，为控制这一关键生物学过程的复杂调控网络提供了线索。
