转录因子EjAP2基因可变剪接调控三倍体枇杷早花的分子机制研究

三倍体枇杷Q11和Q27均是二倍体‘常白1号’实生后代中选育出的优良株系；与亲本和Q27相比，Q11具有早花、果早熟等优良性状。本项目前期通过转录组和表达分析，确定了花分生组织特征决定基因EjAP2存在2个剪接异构体EjAP2_1和EjAP2_2，二者在Q11和Q27（以及大量早晚花三倍体枇杷）花芽分化期均表达差异显著，其中EjAP2_2的AP2结构域发生氨基酸缺失，导致不能与靶标蛋白互作。然而，EjAP2通过可变剪接调控Q11早花的机制尚不清楚。因此，本项目拟：比较两个剪接体的表达时空差异，阐明二者表达模式差异与Q11早花的关系；分析结构域功能和转基因拟南芥开花时间差异，明确AP2结构域变异对EjAP2调控早花功能的影响；比较Q11、Q27和‘常白1号’的EjAP2启动子调控剪接异构体的转录差异，阐明启动子调控差异与早花的关系。最终揭示EjAP2基因可变剪接调控三倍体枇杷早花的分子机制。

Excellent triploid loquats lines of Q11 and Q27 were obtained from seedling progenies of ‘Changbai No.1’. Compared with ‘Changbai No.1’ and Q27, line Q11 showed early-flowering and early maturity of fruits, and is an ideal material for studying flowering time of triploid loquats. Two splice variants EjAP2_1 and EjAP2_2 of the early-flowering related EjAP2 were selected by transcriptome analysis, and their expression levels were significant differences. Meanwhile, EjAP2_2 protein having amino acid deletion of the AP2 domain caused no interaction with target protein. However, their regulatory mechanisms underlying early-flowering of Q11 remain unclear. In this project, the relationship between the expression patterns and early-flowering of Q11 will be clarified by comparing expression levels of two splice variants at different stages. Comparative analyses of protein-protein interaction and transgenic Arabidopsis mutants will be used to investigate the effect of alternative splicing of EjAP2 on the regulation of early-flowering function. Promoter elements of EjAP2 between Q11, Q27 and ‘Changbai No.1’ will be analysed to investigate the effect of transcriptional regulation differences for two splice variants. The results will provide valuable information to understand the regulatory mechanisms of alternative splicing of EjAP2 on early-flowering in triploid loquats.