油菜素甾醇与共生信号通路互作调控大豆根瘤发育的机制研究

Soybean can fix nitrogen within symbiotic nodules, which are formed through interaction between soybean and rhizobium. As growth promoting hormones, brassinosteroids (BRs) can regulate many aspects of plant growth and development through their signal transduction pathway. Interestingly, previous studies found that BRs can inhibit nodulation with an unknown mechanism in soybean. Our previous results indicate that some key signaling components of BR signaling pathway can directly interact with some key components of the symbiotic signaling pathway and can inhibit the symbiotic signaling outputs. In this project, we are going to further use genetic, biochemical, develop biology, and informatics approaches to study the genetic, cellular, and molecular mechanism of the interaction between BR signaling and symbiotic signaling pathways, and to elucidate the molecular mechanism of BR signaling regulating between plant development and nodulation in soybean, which will provide basic knowledge for improving the efficiency of nitrogen fixation in legumes.

大豆通过与根瘤菌互作形成根瘤进行生物固氮。油菜素甾醇（Brassinosteroids，BRs）作为一种促进生长的激素，通过信号转导参与调控植物生长发育的诸多方面。有意思的是，BR还可以抑制大豆-根瘤菌共生结瘤，但是人们对BR调控大豆根瘤发育的机制未知。项目的前期研究发现，大豆中BR信号途径关键组分可以抑制共生信号途径的信号输出，并与共生信号途径的关键组分直接相互作用。我们将继续采用遗传学、生物化学、发育生物学和生物信息学等方法系统揭示BR信号与共生信号途径互作的遗传、细胞和分子机制，揭示BR调控大豆生长发育和共生结瘤的分子机理，为提高豆科植物共生固氮效率提供理论基础。

大豆和根瘤菌互作形成根瘤进行共生固氮。根瘤的发育受到内源和外源因素的严格调控。作为一种促进植物生长的激素，油菜素甾醇（Brassinosteroids，BRs）通过其信号转导通路调控植物发育的诸多过程。早期研究发现，BRs可以抑制大豆共生结瘤，但是其遗传和分子机制未知。本研究通过转录组学实验发现BR信号通路负调控结瘤信号通路。进一步通过遗传学和生物化学等方法证明BR信号通路抑制大豆结瘤通过促进GmBES1-1在细胞核中积累，GmBES1-1直接和共生信号通路核心转录因子GmNSP1a/b以及GmNSP2a/b相互作用，一方面抑制GmNSP1a和GmNSP2a的相互作用，另一方面抑制GmNSP1a的DNA结合能力。综上所述，BRs对GmBES1-1亚细胞定位的精细调控在豆科-根瘤菌共生和植物发育中发挥重要作用。本研究不仅揭示了BR和共生信号通路互作调控大豆结瘤的遗传及分子机制，也为将来通过分子设计育种实现提高固氮效率和促进大豆生长提供潜在靶点。