Li Wenwei, Huang Xiaorong, Zou Jie, Wu Jianjun, Jiao Hengwu, Peng Xiongbo, Sun Meng-Xiang
State Key Laboratory of Hybrid Rice, College of Life Science, Wuhan University, Wuhan 430072, China.
Department of Ecology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Curr Biol. 2020 Dec 7;30(23):4780-4788.e5. doi: 10.1016/j.cub.2020.09.006. Epub 2020 Oct 1.
The gynoecium is derived from the fusion of carpels and is considered to have evolved from a simple setup followed by adaptive adjustment in cell type and tissue distribution to facilitate efficient sexual reproduction [1, 2]. As a sequence of the adjustment, the apical gynoecium differentiates into a stigma and a style. Both the structural patterning and functional specification of the apical gynoecium are critical for plant fertility [3, 4]. However, how the fine structures of the apical gynoecium are established at the interface interacting with pollen and pollen tubes remain to be elucidated. Here, we report a novel angiosperm-specific gene family, STIGMA AND STYLE STYLIST 1-3 (SSS1, SSS2, and SSS3). The SSS1 expresses predominately in the transmitting tract tissue of style, SSS2 expresses intensively in stigma, and SSS3 expresses mainly in stylar peripheral region round the transmitting tract. SSSs coregulate the patterning of the apical gynoecium via controlling cell expansion or elongation. Both the architecture and function of apical gynoecium can be affected by the alteration of SSS expression, indicating their critical roles in the establishment of a proper female interface for communication with pollen tubes. The NGATHA3 (NGA3) transcription factor [5, 6] can directly bind to SSSs promoter and control SSSs expression. Overexpression of SSSs could rescue the stylar defect of nga1nga3 double mutant, indicating their context in the same regulatory pathway. Our findings reveal a novel molecular mechanism responsible for patterning the fine architecture of apical gynoecium and establishing a proper interface for pollen tube growth, which is therefore crucial for plant sexual reproduction.
雌蕊群由心皮融合而来，被认为是从简单结构进化而来，随后在细胞类型和组织分布上进行适应性调整以促进高效有性繁殖[1,2]。作为这种调整的结果，顶端雌蕊群分化为柱头和花柱。顶端雌蕊群的结构模式和功能特化对植物育性都至关重要[3,4]。然而，顶端雌蕊群在与花粉和花粉管相互作用的界面处的精细结构是如何形成的仍有待阐明。在此，我们报道了一个新的被子植物特有的基因家族，柱头和花柱造型基因1 - 3（SSS1、SSS2和SSS3）。SSS1主要在花柱的传递组织中表达，SSS2在柱头中强烈表达，SSS3主要在围绕传递组织的花柱外周区域表达。SSS基因通过控制细胞扩张或伸长共同调节顶端雌蕊群的模式形成。顶端雌蕊群的结构和功能都会受到SSS表达改变的影响，这表明它们在建立与花粉管进行交流的合适雌蕊界面中起着关键作用。NGATHA3（NGA3）转录因子[5,6]可以直接结合到SSS基因的启动子上并控制其表达。过表达SSS基因可以挽救nga1nga3双突变体的花柱缺陷，表明它们处于同一调控途径中。我们的研究结果揭示了一种新的分子机制，该机制负责顶端雌蕊群精细结构的模式形成并建立花粉管生长的合适界面，因此对植物有性繁殖至关重要。
