AP2与赤霉素互作调控拟南芥发育的分子机理

The transcription factor AP2 and gibberellin (GA) participate in flower and seed development, and GA promotes stem elongation, however, it is unknown whether AP2 and GA interact to regulate these development processes. In our previous work, we isolated a new AP2 mutant ap2△R2 by screening EMS-induced Arabidopsis library, which was loss of part AP2R2 domain, and displayed weak floral organ defects and was taller than wild type, and the seeds were malformational and germinated within siliques. Moreover, the double mutant of ap2△R2 and ga1-3, which was defective in GA synthesis, was dwarf and dark green with severely defective flower, and exogenous GA could restore the double mutant to normal phenotype, suggesting that GA can directly take part in floral organ formation. Based on the ap2△R2 mutant, we will hybridize ap2△R2 with ap2 alleles and GA synthesis or signaling mutants, track embryo development, detect seedling germination, observe floral organ morphogenesis and stem elongation, analyze the expression of GA synthesis or signaling genes, and screen GA related genes bound by AP2R2 domain. The execution and fulfillment of the project, will reveal the molecular mechanism for the interaction between AP2 and GA in regulation of flower and embryo development, seed germination and stem elongation, and provide a theoretical basis for crop improvement.

转录因子AP2和赤霉素（GA）在植物花和种子发育中均有重要作用，GA还能促进茎的生长，但AP2和GA是否互作调控上述发育却未见报道。在前期研究中，通过EMS诱变和筛选，我们发现了一个新的拟南芥AP2基因突变体ap2△R2，其AP2R2部分结构域缺失，表现为花器官轻微缺陷、植株变高、种子畸形并发生胎萌。与GA合成缺陷突变体杂交和GA喷施处理结果表明，GA能与AP2互作调控花器官发育。本项目以该突变体为研究材料，拟通过与ap2等位突变体及GA合成代谢和信号转导相关突变体杂交，观察胚胎发育、种子萌发、花器官和茎生长，分析GA相关基因的表达、以及AP2R2蛋白结构域与GA相关基因的结合等，揭示AP2与GA互作调控花和胚胎发育、种子萌发、及茎伸长的分子机理，为改良农作物相关性状提供理论基础。

本项目以拟南芥AP2蛋白AP2R2结构域部分缺失的ap2△R2突变体为材料，系统观察了该突变体胚胎发育过程和种皮结构，发现其与典型的ap2突变体表型相似。超表达AP2和ap2△R2突变体中主要转录本AP2△45导致植株花器官和/或种子异常。数字基因表达谱分析表明AP2R2结构域在种子中特异调节的潜在靶基因并未集中在某一特定通路，但由于ap2△R2种皮颜色加深，与种皮原花色素合成相关的基因可能是重要的靶基因。弱休眠的ap2△R2不能恢复子强休眠的ABA相关突变体表型，暗示AP2可能通过ABA通路调节种子休眠。今后的研究将重点进行AP2R2结构域缺失调节的靶基因验证和遗传生化分析，并结合ABA相关突变体，深入研究AP2在种子发育和休眠中的功能。在本项目资助下发表文章4篇，培养博士生1名，硕士生3名。