苹果MdNLP7转录因子响应不同N素水平调控花芽形成的分子机制

氮对木本果树成花具有显著调控效应，但N过量显著抑制成花，其机制尚待解析？申请者前期通过酵母单杂交筛库及高氮处理RNA-seq数据，发现MdNLP7转录因子可能响应不同N素水平调控富士苹果成花；在此基础上，利用Y1H和EMSA证实MdNIGT1与MdNLP7的转录调控关系，解析高氮条件下，MdNIGT1-MdNLP7模块的反馈抑制调控机制；通过全基因组启动子NRE元件鉴定，结合ChIP-seq数据，筛选MdNLP7调控下游关键靶基因，利用EMSA和ChIP技术，分析MdNLP7与候选成花基因MdLFY3、MdFD和MADS-box（MdAGL79和MdSOC1b）启动子的结合能力，解析其转录调控机制；并利用拟南芥、番茄和苹果转基因体系，验证其功能。研究成果有助于阐明MdNLP7响应不同N素水平调控苹果成花的分子机制，对于提高氮肥利用率，指导果树优质高效生产与可持续发展具有重要理论和实践意义。

Nitrogen has a significant regulatory effect on flower bud formation in woody fruit trees, the appropriate amount of N is the necessary material basis for flower bud formation, but the excessive amount of N has a significant inhibitory effect on flower bud formation. It is not clear about the regulatory mechanism? Baesd on the results of Yeast single hybrid sieve library (Y1H) and RNA-seq data, MdNLP7 transcription factor may regulate the flowering of ‘Fuji’ apple trees in respond to different N levels. On that basis, Yeast one-hybird (Y1H) system and EMSA will be used to analyze the function pattern of MdNIGT1 and MdNLP7 in post-transcriptional control, in order to analyze the contrary expression pattern and feedback inhibition regulation mechanism of MdNIGT1-MdNLP7 module under high nitrogen condition;Through genome-wide promoter NRE element identification in apple genome, combining with ChIP-seq data, the target genes of MdNLP7 were screened; EMSA and chromatin immunoprecipitation (ChIP) techniques were used to analyze the binding ability of MdNLP7 with the promotor of candidate flowering key genes including MdLFY3, MdFD and MADS-box (MdAGL79 and MdSOC1b) for analyzing its transcriptional regulation mechanism.Transgenic systems of Arabidopsis, tomato and apple will be used to identify their functions. The research results are helpful to elucidate the molecular mechanism of MdNLP7 regulating apple flowering in response to different N levels, and improve the nitrogen utilization rate, as well as guide the high quality and efficient production and sustainable development of fruit trees in theory and practice.