MsARF5靶向Aux/IAA家族基因调控天女木兰种子形态休眠解除路径及其机制研究

天女木兰是集观赏、芳香和药用价值于一身的国家重点3级保护野生植物，是木兰科分布最北界的一个物种，开发应用前景广阔。该种子具有典型形态生理休眠特征，种胚发育不完全致使种子萌发、出苗困难，其形态休眠解除机制尚不明晰。申请者基于前期天女木兰种胚发育转录组数据，已验证生长素响应因子MsARF5调控种子后熟胚胎发育，且与多个Aux/IAAs基因转录表达模式显著相关。因此，本项目拟从天女木兰MsARF5靶向Aux/IAAs基因入手，采用转录因子为中心的酵母单杂、原位杂交、染色质免疫共沉淀等技术，通过MsARF5与Aux/IAAs基因体内外互作、转录活性及其调节机制等方面的研究，旨在解析MsARF5-Aux/IAA网络在种子形态休眠解除过程中的调控路径，明确MsARF5-Aux/IAA介导的生长素信号转导调控种胚后熟的分子机制，为具有后熟特性种子的形态休眠解除调控提供科学的依据，丰富种子休眠解除理论。

Magnolia sieboldii K. Koch (M. sieboldii) is a national grade III key protected wild plant with high ornamental, aroma, and medicinal values. It is the northernmost among all Magnoliaceae species and has broad application prospects. M. sieboldii seeds exhibit unique morphophysiological dormancy (MPD) features, in which the embryo is not fully developed and must further develop before germination can occur, however, the molecular mechanism underlying morphological dormancy release remains unclear. Our previous work based on the transcriptome of developing M. sieboldii embryo identified the auxin response factor 5 (MsARF5) as a regulator of embryonic development during after-ripening process of M. sieboldii seed. In addition, the expression pattern of MsARF5 was significantly correlated with those of multiple Aux/IAA genes. Here, we propose to further verify the interaction between MsARF5 and its targeted Aux/IAAs and aim to dissect the interaction network by various in vivo and in vitro experiments, including yeast-one hybrid (Y1H), in-situ hybridization (ISH), and chromatin immunoprecipitation (ChIP). The results will help to understand the mechanisms by which the MsARF5-Aux/IAA network regulates the release of morphophysiological dormancy and by which MsARF5-Aux/IAA-mediated auxin signaling regulates embryonic development during after-ripening process of M. sieboldii seed. The findings of this study will provide a mechanistic basis for the release of morphological dormancy in after-ripening M. sieboldii seeds and offers new insight into future studies on seed dormancy release.