BR信号通过拮抗SHR功能时空决定根木质化的机制研究

植物根成熟区细胞壁的木质化对形成有功能的内皮层和初生木质部是非常必要的。内皮层中特化的一层木质化的结构叫做凯氏带，它是植物根系选择性吸收水分和养分的关键结构。尽管促进凯氏带和初生木质部形成的分子机制的多个关键组分已被确定，但空间决定根系木质化发育转换仍然未知。为了探索植物根系木质化为何能在特定的时空位置形成。申请人前期进行了初步的研究。结果发现过表达SHORT-ROOT(SHR)能使根的木质化提前产生。SHR突变体中凯氏带和初生木质部均消失。酵母双杂文库筛选实验发现SHR能与BR信号中的BZR1互做，且BL处理植物根系能显著推迟空间根木质化的起始。据此，本项目欲阐明BR信号空间决定根木质化起始中的功能以及BZR1与SHR互做调控空间决定根木质化的机制。本项目不仅提出了植物根系木质化存在发育转化的这一发育生物学问题。还有助于理解植物根在特定的时空位置木质化的分子机理。

Cell wall lignification is essential for forming functional endodermis and protoxylem (PX) in the mature zone of plant roots. Lignified apoplastic structure in endodermis is called casparian strip (CS) that is critical for selective absorption of water and nutrients in plant roots. Despite multiple key components of the molecular machinery promoting the formation of CS and PX have been identified, the spatial determination of the developmental shift to the root lignification is still a mystery. Our recent study showed that enhanced SHR level leads to the precocious root lignification and the lignification in both endodermis and PX became undetectable in shr-2. Screening of Yeast two hybrid (Y2H) library showed that SHR could interact with BZR1. Futher, the lignification in endodermis and PX was delayed after the BL treatment. Based on our previous results, to further clarify the function of BR signal in determining the initiation of root lignification and the downstream regulation mechanism of BR and SHR interaction in determining root lignification. In this study not only provide a mechanistic view of the developmental transition to the lignification in plant roots, but also make us better understand the molecular mechanism of lignification at specific position of the root.