开花是果树育种和生产的基础。近期研究已揭示木本果树的成花转变与模式植物一样，也依赖成花素FT基因表达。在草本植物中已证实FT蛋白可以通过维管束从叶片转运到顶端分生组织，但在已开花的成年果树上高接童期材料，却并不能有效缩短童期；转化FT早花材料上嫁接童期苹果和杨树，也未获得早花表型转移的预想结果，表明FT在木本植物中的移动受到限制。本项目拟在前期基础上，对比研究柑橘与拟南芥、番茄维管结构与成分、FT蛋白关键位置氨基酸异同，并互换FT相应区域氨基酸分别转化番茄和柑橘，比较FT移动性；检测柑橘FTIP及FE与FT蛋白互作能力和表达动态变化，以揭示柑橘中FT蛋白移动受限分子机制；采用芽苗嫁接法检验FT在细嫩接穗内移动情况；构建FT与磷脂酰胆碱合成相关基因的双元载体，转化柑橘，并辅加外施处理，观察其对FT蛋白移动的影响，探索提高FT蛋白移动能力的可能性，为提高柑橘育种效率和早结丰产提供新思路。

Flowering is the foundation of fruit breeding and production. Recent study has revealed that woody plants goes similar mechanism in development transition and flowering relying on FT expression. In model herbaceous plants, it has been confirmed that the FLOWERING LOCUS T (FT) proteins can be transported from the leaves to the apical meristem through vascular bundles. However, it is not effective in shortening the juvenile period in adult fruit trees by juvenile material top-grafted on flowering root-stock. In a few recent research reported that juvenile apple and poplar grafted on FT transgenic material did not display early flowering as expected, indicating that the movement of FT in woody plants may be limited. in woody plants. This project intends to compare the similarities and differences of phloem structure, FT protein size and amino acids in key position between citrus and Arabidopsis as well as tomato. By making exchange of the key element of FT protein between citrus and model plants, modified FT protein will be transformed into tomato and citrus respectively to compare the mobility of FT in transgenic plants. In sieve tube and companion cell of citrus, interaction ability of FT-INTERACTING PROTEIN 1 (FTIP1) and phloem-specific Myb-related protein (FE) to FT protein and their dynamic expression will be examined to reveal the refine mechanism of FT protein restriction in citrus. The FT movement within the scion will be also investigated when the infant shoots are grafted by seedling-grafting method on transgenic FT-GFP material. Meanwhile, to further explore the possibility of increasing the mobility of FT proteins, a binary vector of FT and phosphatidylcholine synthesis-related genes will be constructed, transformed into citrus, and supplemented with external treatments to observe its effect on the movement of FT proteins. Thus, the project is expected to improve our knowledge about the basis of flowering in citrus plants and provide a practical strategy to shorten juvenile period and enhance breeding efficiency in citrus.