苹果MdWUS/MdBRC1响应细胞分裂素调控分枝发育的功能与分子机理

Seedlings with good branching status are one of the necessary conditions for apple dwarfing and densely planting, Cytokinin (CTK) regulates branching, BRC1 is a branch-regulated integration factor, However, how BRC1 responds to CTK signal regulation branches remains to be resolved. A previous study found that MdWUS may be a bridge for MdBRC1 to respond to CTK signals, which combines with MdBRC1 to control apple branching. Based on this, the project intends to further research the combination of MdWUS and MdBRC1 by using yeast two-hybrid and pull-down methods, and determine the key areas of interaction by using yeast two-hybrid through segment deletion. The effect of MdWUS as a repressor on BRC1 regulate downstream gene activity was studied by transient transformation of tobacco leaves and apple callus. Finally the branhcing regulation function of MdWUS was also verified by apple transgene. Through the analysis of the molecular mechanism of apple MdWUS/MdBRC1 in response to CTK regulation of branching will provide theoretical guidance for the regulation of branch development in high quality and efficient cultivation of apple.

分枝状况良好的苗木是苹果矮化密植建园的必要条件之一；细胞分裂素（CTK）具有调控苹果等木本植物分枝发育的效应，BRC1是分枝调控网络的整合因子；但BRC1如何响应CTK信号调控分枝尚待解析。申请者前期发现苹果MdWUS可能是MdBRC1应答CTK信号的桥梁，其通过和MdBRC1结合调控分枝发育。本项目拟在此基础上，进一步采用酵母双杂交、蛋白质体外结合研究MdWUS、MdBRC1的互作关系，利用酵母双杂交区段删减分析互作的关键区域；通过烟草叶片、苹果愈伤组织瞬时转化研究MdWUS作为抑制子对MdBRC1转录调控下游基因活性的影响；另外通过苹果转基因分析MdWUS调控分枝的功能。通过该项目的开展，深入解析苹果MdWUS/MdBRC1响应CTK调控分枝的分子机理，为苹果优质高效栽培中的分枝发育调控提供理论指导。

分枝状况良好的苗木是苹果矮化密植建园的必要条件之一；细胞分裂素（CTK）具有调控苹果等木本植物分枝产生发育的效应，BRC1（TCP家族成员）是分枝调控网络的整合因子。本项目研究发现MdWUS2响应CTK上调表达，酵母双杂交、BIFC、Co-IP显示MdWUS2和MdTCP12存在互作；烟草叶片瞬时转化，双荧光素酶实验发现MdWUS2和MdTCP12结合后抑制MdTCP12对MdHB53b的激活作用；拟南芥过表达WUS2后分枝增多，相反过表达TCP12后分枝减少。通过该项目的开展，深入解析苹果MdWUS2/MdTCP12响应CTK调控分枝的分子机理，为苹果优质高效栽培中的分枝发育调控提供理论指导。