RND1调控根瘤形成和侧根发育分子机制的研究

The rhizobial symbiotic interaction which is beneficial to both partners could be formed between legumes and compatible rhizobia. It has been shown that pericycle cells adjacent to xylem poles are also activated and divide before cortex cell division during nodule formation, which showed the similar character with lateral root initiation. Moreover, small peptide CEP1 and phytohormone such as auxin and cytokinin, which are required for lateral root development, are all involved in nodule initiation and development, suggesting an overlap mechanism under lateral root initiation and nodule formation. A new rnd1 (Root and Nodule development), which is defective in lateral root and nodule development, is isolated from a forward genetic screening in Medicago truncatula. We cloned RND1 gene and found that RND1 encodes a putative transcription factor. Furthermore our primary data showed RND1 interacts with nodulation specific GRAS type transcription factor NSP1. Our research will focus on the genetics, biochemistry, cell biology of RND1 and whole transcriptomes of specific cell types in wild type and mutant to uncover the mechanism under lateral root and nodule formation.

豆科植物的根能够与根瘤菌互作形成根瘤，根瘤菌在根瘤中能够把游离态的氮转化成结合态氮化合物供植物生长。植物的侧根能够固定植物帮助植物吸收养分和水。根瘤和侧根都是后生器官，发育早期都有紧邻原生木质部的中柱鞘细胞活化和分裂的现象。影响侧根形成的小肽CEP1和植物激素如生长素和细胞分裂素等也参与根瘤的发育，表明豆科植物中侧根和根瘤的形成存在着密切的联系。前期申请人在蒺藜苜蓿中筛选突变体的方法获得rnd1 （Root and Nodule development）突变体，该突变体表现为根瘤起始受限，侧根数目减少。克隆RND1基因表明其编码的一个转录因子，酵母双杂交实验发现：RND1与根瘤特异的转录因子NSP1相互作用。本项目将在此基础上，利用转基因和生化的技术，并结合激光显微切割的方法捕获RND1调控根瘤发育基因的特异表达谱，并对其进行深入分析。希望以RND1为突破口，揭示根瘤和侧根发育的分子机制。