IbMADS11基因在甘薯块根发育中的功能及调控机理研究

The most important physiological process in sweet potato production is tuberous root development. However, to date, the molecular mechanisms of tuberous root inatiation and development remain unclear. In our previous study, a MADS-box gene that related to sweet potato tuberous root production was cloned by transcriptional profiling, here named as IbMADS11. Quantitative RT-PCR showed that IbMADS11 mainly expressed in the early stage of sweet potato tuberous roots, indicating that it might be involved in regulating tuberous root development. In this project, an RNAi expression vector and an over-expressed vector of IbMADS11 will be constructed and transformed into sweet potato plants. The morphological changes and physiological characteristics of transgenic sweet potato lines will be analyzed to explore the function of IbMADS11 in tuberous root development. The IbMADS11-regulated candidate genes will be detected by RNA-seq and quantitative RT-PCR. Moreover, interactions between IbMADS11 and other sweet potato MADS-box proteins will be revealed by yeast two-hybrid assay and fluorescence resonance energy transfer. This project will help better to elucidate the mechanisms of sweet potato tuber development and hold promising application in regulating sweet potato tuberous root yield.

甘薯产量与块根发育过程密切相关，了解块根形成和膨大的机制对提高甘薯产量至关重要。然而，迄今为止，块根发育的分子机理尚不清楚。本实验室通过转录组分析，克隆到一个与甘薯块根产量密切相关的MADS-box基因，命名为IbMADS11。定量RT-PCR分析表明，该基因主要在甘薯块根形成初期大量表达，暗示该基因可能参与调控块根的发育。本研究拟在甘薯中超表达和沉默IbMADS11基因，对转基因甘薯块根进行切片观察及生理生化分析，研究IbMADS11在块根发育中的功能；利用RNA-seq及定量RT-RCR技术研究IbMADS11对块根发育相关基因的影响，探索IbMADS11基因调控块根发育的机理；利用酵母双杂交和荧光共振能量转移法，研究IbMADS11蛋白与其它MADS-box蛋白的互作情况，挖掘潜在的块根发育调控因子，从而为全面阐明甘薯块根膨大机理及利用基因工程调控块根膨大奠定基础。

块根膨大是影响甘薯产量最重要的生理因素。本研究克隆了一个与甘薯块根发育密切相关的MADS-box基因IbMADS11。表达模式分析发现该基因在甘薯块根形成初期大量表达。亚细胞定位结果表明，该基因定位于细胞核。在甘薯中沉默该基因，转基因甘薯表现为块根膨大加速的现象。进一步检测发现，转基因甘薯中内源细胞分裂素及生长素含量升高，块根发育相关基因表达量升高。而IbMADS11异源超表达番茄转基因植株表现出根发育受抑制的现象。表明IbMADS11在块根形成过程发挥重要功能。酵母双杂交及双分子荧光互补实验表明，IbMADS11与块根发育特异因子SRD1相互作用，表明IbMADS11可能通过与SRD1互作，共同调控了甘薯块根发育。此外，IbMADS11还与其他两个MADS-box蛋白IbMBP1和IbMBP8相互作用，暗示这两个蛋白可能也与块根发育相关。这些结果表明，IbMADS11基因是调控甘薯块根形成及发育的重要因子。本研究为甘薯块根发育的分子调控网络研究奠定了基础，为利用基因工程技术培育高产甘薯品种提供了理论依据。