柑橘新梢生长到一定阶段后顶端便不再生长，顶端优势解除，继而发生自动断裂脱落的现象称为“自剪”，是柑橘新梢发育、营养供应的转折点，其具体的调控机制尚不明确。前期通过表达谱分离到两个含有homeobox结构域基因（CsHD1和CsHD2），其表达模式与新梢自剪密切相关并在顶端分生组织特异表达，遗传转化模式植物发现可以解除顶端优势，转基因植物呈现出节间变短与侧芽簇生等表型。本项目拟在前期研究的基础上，通过遗传转化柑橘鉴定其功能，并利用酵母单杂交、EMSA和双荧光素酶系统等技术鉴定其上游调控因子；通过酵母双杂交、双荧光互补等分离下游互作蛋白，然后利用模式植物对上下游基因进行功能验证；最后调查CsHD1和CsHD2及其上下游调控基因在柑橘中的表达模式，最终解析CsHD1和CsHD2调控柑橘新梢自剪发生的分子机制。本项目的顺利实施对调控柑橘开花及其生产上简化栽培调控树形具有潜在的应用价值。

The shoot apical meristem of the new shoots no longer grow when the citrus shoots develop to a certain stage, the apical dominance will be lifted, and then shoot apical meristem is automatically broken off and detached, called "self-cutting". It is a turning point in the development of citrus shoots and nutrient supply. However, the specific regulation mechanism of self-pruning is still unclear. In the previous study, two genes containing the homeobox domain (CsHD1 and CsHD2) were isolated by transcriptome sequencing. Their expression pattern were closely related to self-pruning of citrus new shoot and specific expression in the apical meristem. Genetic transformation experiments have found that the apical dominance of transgenic plants can be relieved, and transgenic plants exhibit shorter internodes and lateral buds. Based on the previous research, this project is proposed to identify the functions of these two genes by genetic transformation of citrus, and to identify its upstream regulatory factors by yeast one-hybrid, electrophoretic mobility shift assay (EMSA) and dual luciferase systems; further isolate the downstream interaction genes by yeast two-hybrid, double-fluorescence complementation (BiFC), etc. The apical development of citrus new shoots is specifically regulated by upstream and downstream interaction genes, the expression patterns of CsHD1 and CsHD2 and their upstream and downstream regulatory genes were also analyzed in citrus after treatment with different hormones. Finally, the molecular mechanisms of CsHD1 and CsHD2 regulating the self-shearing of citrus new shoots were analyzed. The project has potential application value for regulating citrus flowering and simplifying cultivation and regulation of tree shape.