MAPK级联路径基因CmMPK1调控菊花侧枝发育的机制研究

Branching development is not only a critical morphological trait in plant, but also an important quality trait of chrysanthemum, which determines the types of its variety and production costs directly. The interaction between hormone signaling has always been the focus to discover on the regulation mechanism of plant branching. Meanwhile, the MAPK cascades play a role in signal transduction in these hormone pathways, but the molecular mechanism is not clear yet. MAPK cascades have been found to involve in the regulation of lateral buds development in chrysanthemum by bioinformatics analysis and molecular biology experiments. Therefore, the present proposal focuses on CmMPK1, which could regulate lateral buds development of chrysanthemum. In order to elucidate the basic functions of CmMPK1, a member of MPK in Group C, we will carry out a series of experiments including subcellular localization, RNA in situ hybridization, point mutation, genetic transformation and transcriptome analysis. The cDNA library of lateral buds in chrysanthemum will be constructed. Through the yeast two-hybridization, physiological and biochemical, and transgenic experiments, the upstream and downstream regulatory network of CmMPK1 protein will be explored, and the mechanism of MPK protein in Group C will also be interpreted. The project could not only improve the knowledge in regulatory network of plant branching development, but also provide an elite gene pool for directional breeding of chrysanthemum cultivars with different branching traits.

侧枝发育在植物形态建成中占有重要地位，也是园林植物菊花的重要品质性状，直接决定其品种类型及生产成本。激素信号之间的互作一直是植物分枝调控机理研究关注的焦点，而MAPK级联路径在这些激素通路中起信号转导作用，但其分子作用机理尚不明确。课题组前期通过生物信息学筛选及分子生物学实验验证，发现MAPK级联路径参与了菊花侧枝发育的调控。为此，本项目围绕菊花侧枝发育调控基因CmMPK1，拟开展亚细胞定位、RNA原位杂交、点突变、遗传转化和转录组分析等实验，阐明C组MPK成员CmMPK1的基本功能；构建菊花侧枝发育文库，通过酵母双杂交、生理生化及转基因等实验，探明CmMPK1上下游蛋白互作的调控网络，完善对C组MPK蛋白作用机制的理解。本项目的实施不仅可以完善植物侧枝发育的调控网络，还可为定向培育不同分枝类型菊花品种提供基因储备。

植物株型在植物发育生物学研究中占有重要地位，也是园林植物菊花的重要品质性状，直接决定其品种类型及生产成本。激素信号之间的互作一直是植物株型调控机理研究关注的焦点，而MAPK级联路径在这些激素通路中起信号转导作用，但其分子作用机理尚不明确。课题组前期通过生物信息学筛选及分子生物学实验验证，发现MAPK级联路径的CmMPK1参与了菊花株型的调控。为此，本项目围绕CmMPK1调控菊花株型的开展了系统研究，发现组成型激活的CmMPK1超表达可导致菊花植株矮化，并证明了该表型是由赤霉素通路受阻引起的，完善了对C组MAPK的生物学功能及作用机制的理解。通过体内体外实验最终构建了以CmMPK1为核心的调控菊花株型工作模型：3个磷酸激酶CmMAPKKK4、CmD6PKL2和CmWNK8能磷酸化CmMPK1，而CmMPK1能磷酸化下游3个转录因子CmVOZ1、CmbZIP18和CmBLH2从而参与对菊花株型的调控，同时还有7个MAPK磷酸酶参与CmMPK1的去磷酸化，介导了CmMPK1完成信号转导后的失活机制。本项目的实施不仅完善了植物株型的调控网络和MAPK的作用机制，还可为定向培育不同株型菊花品种提供基因储备。