转录因子IbBEL1-6调控甘薯块根膨大的功能研究

Tuberous is the most important factor on sweetpotato yield. But the tuberization molecular mechanism of sweetpotato is still unclear. In our early study, a transcriptional factor gene IbBEL1-6 which was highly responded to tuberization has been found base on the high-throughput sequencing and gene chip results. It has been reported that BEL1 genes were involved in root development and tuberization in Arabidopsis and potato, respectively. Our results also showed that transcriptional level of IbBEL1-6 was significantly enhanced in tuberous roots, and regulated by hormones as related to tuberization. These results are indicating that IbBEL1-6 may be one of the molecular bases of tuberization in sweetpotato. In this project, we planted to investigate the functions of IbBEL1-6 during tuberization in sweetpotato. An in situ hybridization assay will carry out to clarify the expression pattern of IbBEL1-6. The impact of IbBEL1-6 involved in tuberization would be respectively testified on root and whole plant levels by the hairy root and whole plant transformation system. Furthermore, we planted to demonstrate the downstream genes and signaling network regulated by IbBEL1-6 transcription factor through transcriptome analyses. This project aims at revealing the molecular mechanism of IbBEL1-6 involved in sweetpotato tuberization, and providing the candidate genes and theory basis for breeding new sweetpotato varieties with high yield.

块根膨大是决定甘薯产量的最重要因素，但是其分子机制却尚不明确。本课题组前期通过高通量测序、基因芯片筛选到对块根膨大强烈响应的转录因子基因IbBEL1-6; BEL1基因被报道跟拟南芥根系发育和马铃薯块茎形成相关，前期表达模式分析表明IbBEL1-6在块根表达量显著增加并受块根膨大相关激素调控，说明该基因可能是解析块根膨大的分子机制之一。本项目将在现有的研究基础上，研究IbBEL1-6在甘薯块根膨大过程中的功能。利用原位杂交技术明确其作用部位；通过毛状根和整株转化技术平台，从根系和植株水平研究IbBEL1-6对块根膨大的作用；通过转录组学分析，研究IbBEL1-6转录因子调控的下游基因和信号网络，以期解析转录因子基因IbBEL1-6调控甘薯块根膨大的分子机理，为培育高产甘薯品种提供候选基因和理论基础。

甘薯IbBEL1-6参与了甘薯块根膨大过程。本课题通过分子生物学、生物信息学、细胞生物学、遗传转化等方法与技术，对IbBEL1-6参与甘薯块根膨大过程的分子机制进行了初步研究。首先通过RT-PCR方法分析IbBEL1基因家族的表达模式，结合生物信息学分析，筛选出与甘薯块根膨大相关的转录因子IbBEL1-6。进而利用RACE技术克隆了IbBEL1-6基因的全长，明确了IbBEL1-6基因的表达模式，揭示了IbBEL1-6起作用的时间、部位、响应的激素信号途径以及对非生物胁迫的响应，结果表明IbBEL1-6参与了甘薯块根膨大。通过IbBEL1-6融合GFP蛋白的瞬时表达，发现IbBEL1-6在细胞核表达，说明其作为转录因子在细胞核中调控下游基因的转录表达。通过RNA探针原位杂交发现IbBEL1-6只在皮层薄壁组织上检测到，表明IbBEL1-6可能是在块根膨大时期营养物质的累积这一环节起作用。通过IbBEL1-6的过量表达和RNAi载体转甘薯植株，获得了转基因甘薯植株。综合上述结果，本研究为阐明IbBEL1-6参与甘薯块根膨大的分子机质奠定了基础，对认识BEL1基因家族在甘薯的功能提供了重要的线索。项目资助发表SCI论文2篇，获批授权专利1项。项目投入经费19万元，支出17.84万元，结余1.16万，各项支出基本与预算相符。剩余经费计划用于本项目研究后续支出。