梅花两个AGL6类MADS-box基因功能分析及歧化机理研究

Flower is the important ornamental organ for plants and the development of flower organs affect the ornamental value of ornamental plants. During the long cultivation process, the number and morphology of flower organs in Prunus mume varied greatly. However, little is known about the molecular mechanisms that control flower organ development in P. mume. AGL6-like MADS-box genes play important roles in flower organ development and our previous study have suggested that the function of the two duplicated P. mume AGL6 genes diverged after the duplication event. However, the function they played during flower development and the divergence mechanism of them are largely unknown. In this project, we intend to clone these two duplicated AGL6-like MADS-box genes from P. mume, then to study their promoter functions, expression patterns, protein-protein interactions and their roles in Arabidopsis development to elucidate their roles during P. mume flower organ development. These will optimize the molecular model of flower development in P. mume which we proposed previously. Furthermore, we will analyze their differences in promoter, expression patterns, protein-protein interactions and roles in Arabidopsis development to clarify the functional divergence mechanism of them. The results of this project will add to our understanding of the molecular mechanisms that control flower development and formation of different flower types in P. mume and lay a foundation for using AGL6-like genes to modify flower type. Furthermore, the results of this study will also provide the basis for investigating the functional divergence of duplicated genes.

花是植物重要的观赏部位，花器官的发育直接影响到园林植物的观赏价值。梅花在长期栽培过程中，花器官的数量和形态发生了丰富的变化，但花发育的分子调控机理却缺乏研究。AGL6类MADS-box基因在植物花器官发育中发挥着重要的调控作用，我们前期的研究发现，梅花基因组中两个复制的AGL6基因的功能发生了歧化，但它们在花器官发育中的具体功能和功能歧化机理并不清楚。本项目拟以梅花这两个复制的AGL6基因为研究对象：（1）通过系统分析这两个基因的启动子功能、表达模式、蛋白互作模式、在拟南芥发育中的功能，明确这两个基因在梅花花器官发育中的功能，完善梅花花器官发育的分子调控模型；（2）通过对比两个基因在上述方面的差异，阐明这两个基因的功能歧化机理。本项目研究结果将有助于解析梅花花器官发育和不同花型形成的分子调控机理，为利用AGL6类基因改良梅花花型提供理论依据；并为深入研究复制基因功能歧化机理奠定基础。

花是观赏植物重要的观赏部位，花发育与花器官形态直接影响到观赏植物的观赏价值。MADS-box类转录因子在植物花发育中发挥了重要的调节作用。梅花基因组中有两个位于片段复制区域内的AGL6类MADS-box基因，这两个基因的功能发生了歧化，但它们的具体功能和歧化机理尚不清楚。本项目通过分析这两个基因启动子、表达模式、蛋白互作模式、在拟南芥发育中的作用明确了这两个基因的功能并探讨了其歧化的机理。梅花两个AGL6基因均为MIKC类MADS-box基因，二者均含有AGL6类基因特有的保守基序；系统进化树表明AGL6基因的复制发生在梅花与桃分化之前；梅花两个AGL6基因的启动子序列发生了较大的分化，虽然这两个启动子含有的顺式作用元件种类相似，但元件数量和排列顺序差异较大；荧光定量PCR结果表明这两个基因表达部位都主要集中在花器官和果实，但二者表达模式存在一定差异；酵母双杂交和荧光双分子互补实验表明这两个基因的蛋白互作模式存在明显差异，PmAGL6-1可以与A、B、C、E类MADS-box基因都发生相互作用，而PmAGL6-2则只与A类基因发生相互作用；将这两个基因在野生型拟南芥中异位表达发现，这两个基因在拟南芥发育中的作用类似，都是调节了开花时间和花器官及花序的发育。以上结果说明表达模式和蛋白互作的分化是梅花两个AGL6基因功能歧化的主要原因。