影响甘薯块根产量关键基因的鉴定与功能研究

Although sweet potato [Ipomoea batatas (L.) Lam.] is an important crop and a highly promising organism for bioenergy, little is known in molecular bases underlying its agronomically important traits especially for the yield of tuberous root. In our previous work, we have conducted an associative transcriptomics study using 220 sweet potato varieties selected from National Center for Sweet Potato Improvement and identified a large number of candidate genes for agronomically important traits of sweet potato. In this proposal, we planned to functionally validate and investigate six selected candidate genes significantly associated with the yield of tuberous root using the transgenic technology, and to assess their overall roles in influencing the yield of tuberous root in sweet potato. Then, we would focus on the most important gene that were validated (i.e., the key gene) and study its subcellular localization, its temporal and spatial pattern of mRNA expression to interpret its possible role during the development of tuberous root. Using transgenic materials, we also proposed to investigate the transcriptome profile and gene regulatory network mediated by the key gene. Moreover, we would explore the interspecific and intraspecific genetic variations in the key gene and anticipate their impacts on the yield of tuberous root in sweet potato. The evolutionary pattern of the key gene would then be estimated and the key-gene-specific molecular markers would be developed for sweet potato breeding in the future. Our study could show an excellent example on how to overcome the technical bottleneck of forward-genetics research, advance our understanding toward the molecular basis underlying the yield of tuberous root, and provide important information for molecular breeding in sweet potato.

甘薯是重要的农作物和极具开发前景的生物能源材料，但是人们对甘薯重要农艺性状（特别是块根产量）的分子基础知之甚少。在前期工作中，我们从国家甘薯改良中心选用了220个甘薯品种，开展了关联转录组学研究，鉴定到了一批与甘薯重要农艺性状显著关联的候选基因。本项目拟利用转基因技术，对精选的六个影响甘薯块根产量的候选基因进行功能验证与研究，评估它们对甘薯块根产量的影响。之后，我们将聚焦于一个关键基因，研究该基因的亚细胞定位、mRNA表达时空及其在块根发育过程中的作用；利用相应的转基因材料，我们将进一步研究该基因介导的转录组表达谱和基因调控网络。此外，我们将研究该基因在甘薯种内、种间的遗传变异及其对甘薯块根产量的影响，推测该基因的进化模式，开发相应的分子标记。本项目有望克服甘薯正向遗传学研究的技术瓶颈，阐明一个影响甘薯块根产量的分子调控机制，为甘薯分子育种提供重要的理论依据。

甘薯是个重要的块根类作物，但是人们对甘薯块根发育与产量控制的分子基础仍然知之甚少。在前期工作中，我们从国家甘薯改良中心选用220个甘薯品种，开展了关联转录组学研究，鉴定到了一批与甘薯重要农艺性状显著关联的候选基因。本研究中，我们挑选了16个与甘薯块根发育与产量相关的候选基因，通过组织培养与遗传转化实验成功获得了其中8个基因的转基因成苗，发现改变这8个基因（分别命名为IbTGR1-8）的表达时空均影响了甘薯块根的生长，验证了我们的关联转录组分析结果具有很高的可靠性。我们利用获得的转基因材料开展了进一步的分析，包括形态学观察、生理生化指标分析、基因表达分析等。我们的研究发现，IbTGR1和IbTGR2是甘薯块根膨大的关键因子，很可能作用于同一个分子通路，它们控制了甘薯根部次生生长的启动。IbTGR5是另一个影响甘薯块根次生生长的关键因子。总之，本研究鉴定到了多个调控甘薯块根发育的关键基因，其中部分基因很可能在同一个分子模块中行使功能。这些发现为进一步阐明甘薯发育与块根产量的分子机制打下了重要的基础。