谷氨酸受体蛋白PagGLR55参与杨树维管组织发育的分子机制

Forest is not only used for construction and paper making, but also as the main source of biomass energy. At present, the molecular regulation mechanism of wood formation is not very clear. Previous study showed that AtGLR3.1 has a significant accumulation in vascular tissues, indicating that GLR is involved in the regulatory network of vascular tissues. The molecular function of GLR involves many Ca2+-related molecular biological mechanisms, and Ca2+ abundance can directly affect vascular formation and the final wood properties. The program intends to analyze the expression profiles of Populus GLR gene family members during the process of vascular development and characterize the related PagGLR55 genes. The overexpression and CRISPR/Cas9-induced knockout of Populus plants are employed to explore the performance of PagGLR55 on stem vascular tissue structure and developmental mechanism of woody plants. To reveal the regulation of PagGLR55 in the development of tree vascular tissue, and to elucidate how the Ca2+ signaling pathway regulates the mechanism of wood formation. The gene expression profiles, yeast one-hybrid, EMSA methods will be used for screening and analyzing the PagGLR55 upstream regulated target genes related to vascular development. This project is aimed to elucidate the GLR roles in vascular tissue development and how does Ca2+ signal pathway regulate the mechanism of wood formation. Our work further provides novel insight into mechanisms underlying regulatory network of wood development and offer theoretical guidance for directional improvement wood quality and yield through genetic engineering means.

树木是建材和造纸工业的主要原料，也是潜在的纤维生物质能源的来源。阐明树木木材形成的分子调控机制是实现其分子改良的基础。拟南芥谷氨酸受体蛋白（Glutamate Receptor）AtGLR3.2在快速生长的维管组织中有显著积累，这表明其可能参与维管组织的发育过程。GLR分子功能涉及许多Ca2+相关分子生物学机制, 而且Ca2+丰度能够直接影响维管形成及最后的木材性质。本课题以杨树为材料，进一步分析GLR在木本植物维管组织发育中的作用。依据杨树GLR不同成员在茎中的表达模式，克隆与维管组织发育相关的PagGLR55基因并鉴定其上游调控基因。利用杨树GLR过表达和CRISPR/Cas9介导的基因敲除植株，分析PagGLR55基因对木本植物茎维管组织结构发育模式的影响，以揭示GLR在树木维管组织发育中的调控作用，阐明Ca2+信号途径调控木材形成的机制，为木材形成机制的阐释提供基础。

树木木材的形成涉及复杂的调控网络，阐明维管组织调控机制是实现其分子改良的基础。钙(Ca)是一种信号分子，参与植物根、茎的发育的调控。然而，分子机制尚不明确。本研究中，我们分析了84K杨树(Populus alba×P.glandulosa)在不同钙浓度下的形态和转录组变化，共表达分析表明，各模块均存在Ca2+通道谷氨酸受体(GLRs)，对根、茎发育具有重要意义。两个GLR同源基因PagGLR3.3a和PagGLR3.3b主要在根、茎中表达，在Ca2+缺乏时表达上调。CRISPR/cas9介导的突变体侧根更多、更长，茎中木质部加宽等性状。解剖分析表明，PagGLR3.3敲除植株具有更多的木质部细胞，促进次生维管组织的发育。进一步的转录组分析表明，敲除PagGLR3.3a和PagGLR3.3b后，与蛋白质磷酸化、生长素外排、木质素和半纤维素生物合成以及转录调控相关的几个基因上调，这可能有助于侧根的生长和木质部的形成。这项研究不仅为Ca2+通道如何介导树木根和茎生长发育提供了新的见解，而且为生物燃料和生物能源生产的杨树新品种的育种提供了指导。