IbBLH1的长距离运输特性及调控甘薯块根膨大的分子机理研究

块根是甘薯生产的主要收获目标，目前块根膨大的分子机制尚不清楚。本实验室通过转录组、蛋白组和蛋白互作同时筛到一个在甘薯块根形成初期大量表达，且与块根膨大因子SRD1特异互作的BEL类homeobox转录因子IbBLH1。前期研究发现，IbBLH1对块根膨大相关激素响应强烈，且其3´非编码区富含CU基序（RNA长距离移动关键结合信号），表明IbBLH1可能具有长距离移动特性并在块根发育中发挥重要作用。本研究拟培育IbBLH1敲除及超表达转基因甘薯，明确IbBLH1的功能；利用Chip-seq及EMSA分析IbBLH1的靶基因及结合基序；通过异源嫁接及EMSA分析IbBLH1的长距离移动特性；利用BiFC和pull-down分析IbBLH1-SRD1的互作功能域及作用机制，明确IbBLH1在甘薯块根膨大中的作用机理。本研究可为全面解析甘薯块根膨大机制提供参考，为培育高产优质甘薯品种奠定分子基础。

Storage roots are the main products of sweet potato (Ipomoea batatas L.), but the molecular mechanisms of storage root thickening remain unclear. Here, we cloned a BEL-Like homeobox transcription factor, hereafter denoted IbBLH1, by using transcriptome, proteome and protein interaction assays. This protein was highly expressed in early-stage sweet potato storage roots, and interacted with SRD1, a sweet potato storage root thickening-related protein. Further research showed that IbBLH1 responded markedly to storage root development-related hormones, and multiple CU motifs, a key signal for long-distance transportation, were found in the 3´ UTR of IbBLH1. These results indicated that IbBLH1 might be a mobile RNA and play an essential role in the development of storage roots. In this project, overexpressed and knockout transgenic sweet potato plants will be generated to explore the function of IbBLH1. Furthermore, the target genes of IbBLH1 will be identified by ChIP-seq and electrophoretic mobility shift assay (EMSA). The mobile RNA characteristic of IbBLH1 will be analyzed and confirmed by grafting and EMSA. Meanwhile, the functional domain responsible for the interaction between IbBLH1 and SRD1 will be confirmed and their interaction mechanism will be revealed by pull-down and bimolecular fluorescence complementation (BiFC) assays. This project will help improve the understanding of the mechnisms underlying storage root thickening and establish a molecular foundation for breeding high-yield and high-quality sweet potato varieties.